leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
fd7d5287fd
linux/kernel/sched/cpufreq_schedutil.c

792 lines
21 KiB
C
Raw Normal View History

cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
/*
* CPUFreq governor based on scheduler-provided CPU utilization data.
*
* Copyright (C) 2016, Intel Corporation
* Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
cpufreq: schedutil: Improve prints messages with pr_fmt Prefix print messages with KBUILD_MODNAME, i.e 'cpufreq_schedutil: '. This helps to keep similar formatting for all the print messages particular to a file and identify those easily in kernel logs. Its already done this way for rest of the governors. Along with that, remove the (now) redundant bits from a print message. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-05-18 12:25:28 +00:00
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
#include "sched.h"
sched/headers: Simplify and clean up header usage in the scheduler Do the following cleanups and simplifications: - sched/sched.h already includes <asm/paravirt.h>, so no need to include it in sched/core.c again. - order the <linux/sched/*.h> headers alphabetically - add all <linux/sched/*.h> headers to kernel/sched/sched.h - remove all unnecessary includes from the .c files that are already included in kernel/sched/sched.h. Finally, make all scheduler .c files use a single common header: #include "sched.h" ... which now contains a union of the relied upon headers. This makes the various .c files easier to read and easier to handle. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 11:20:47 +00:00
#include <trace/events/power.h>
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
struct sugov_tunables {
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
struct gov_attr_set attr_set;
unsigned int rate_limit_us;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
};
struct sugov_policy {
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
struct cpufreq_policy *policy;
struct sugov_tunables *tunables;
struct list_head tunables_hook;
raw_spinlock_t update_lock; /* For shared policies */
u64 last_freq_update_time;
s64 freq_update_delay_ns;
unsigned int next_freq;
unsigned int cached_raw_freq;
/* The next fields are only needed if fast switch cannot be used: */
struct irq_work irq_work;
struct kthread_work work;
struct mutex work_lock;
struct kthread_worker worker;
struct task_struct *thread;
bool work_in_progress;
bool need_freq_update;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
};
struct sugov_cpu {
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
struct update_util_data update_util;
struct sugov_policy *sg_policy;
unsigned int cpu;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
bool iowait_boost_pending;
unsigned int iowait_boost;
unsigned int iowait_boost_max;
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
u64 last_update;
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
/* The fields below are only needed when sharing a policy: */
unsigned long util_cfs;
unsigned long util_dl;
unsigned long max;
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
/* The field below is for single-CPU policies only: */
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
#ifdef CONFIG_NO_HZ_COMMON
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
unsigned long saved_idle_calls;
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
#endif
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
};
static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
/************************ Governor internals ***********************/
static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
{
s64 delta_ns;
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
/*
* Since cpufreq_update_util() is called with rq->lock held for
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
* the @target_cpu, our per-CPU data is fully serialized.
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
*
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
* However, drivers cannot in general deal with cross-CPU
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
* requests, so while get_next_freq() will work, our
cpufreq: schedutil: Always process remote callback with slow switching The frequency update from the utilization update handlers can be divided into two parts: (A) Finding the next frequency (B) Updating the frequency While any CPU can do (A), (B) can be restricted to a group of CPUs only, depending on the current platform. For platforms where fast cpufreq switching is possible, both (A) and (B) are always done from the same CPU and that CPU should be capable of changing the frequency of the target CPU. But for platforms where fast cpufreq switching isn't possible, after doing (A) we wake up a kthread which will eventually do (B). This kthread is already bound to the right set of CPUs, i.e. only those which can change the frequency of CPUs of a cpufreq policy. And so any CPU can actually do (A) in this case, as the frequency is updated from the right set of CPUs only. Check cpufreq_can_do_remote_dvfs() only for the fast switching case. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-14 09:20:16 +00:00
* sugov_update_commit() call may not for the fast switching platforms.
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
*
* Hence stop here for remote requests if they aren't supported
* by the hardware, as calculating the frequency is pointless if
* we cannot in fact act on it.
cpufreq: schedutil: Always process remote callback with slow switching The frequency update from the utilization update handlers can be divided into two parts: (A) Finding the next frequency (B) Updating the frequency While any CPU can do (A), (B) can be restricted to a group of CPUs only, depending on the current platform. For platforms where fast cpufreq switching is possible, both (A) and (B) are always done from the same CPU and that CPU should be capable of changing the frequency of the target CPU. But for platforms where fast cpufreq switching isn't possible, after doing (A) we wake up a kthread which will eventually do (B). This kthread is already bound to the right set of CPUs, i.e. only those which can change the frequency of CPUs of a cpufreq policy. And so any CPU can actually do (A) in this case, as the frequency is updated from the right set of CPUs only. Check cpufreq_can_do_remote_dvfs() only for the fast switching case. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-14 09:20:16 +00:00
*
* For the slow switching platforms, the kthread is always scheduled on
* the right set of CPUs and any CPU can find the next frequency and
* schedule the kthread.
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
*/
cpufreq: schedutil: Always process remote callback with slow switching The frequency update from the utilization update handlers can be divided into two parts: (A) Finding the next frequency (B) Updating the frequency While any CPU can do (A), (B) can be restricted to a group of CPUs only, depending on the current platform. For platforms where fast cpufreq switching is possible, both (A) and (B) are always done from the same CPU and that CPU should be capable of changing the frequency of the target CPU. But for platforms where fast cpufreq switching isn't possible, after doing (A) we wake up a kthread which will eventually do (B). This kthread is already bound to the right set of CPUs, i.e. only those which can change the frequency of CPUs of a cpufreq policy. And so any CPU can actually do (A) in this case, as the frequency is updated from the right set of CPUs only. Check cpufreq_can_do_remote_dvfs() only for the fast switching case. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-14 09:20:16 +00:00
if (sg_policy->policy->fast_switch_enabled &&
!cpufreq_can_do_remote_dvfs(sg_policy->policy))
sched: cpufreq: Allow remote cpufreq callbacks With Android UI and benchmarks the latency of cpufreq response to certain scheduling events can become very critical. Currently, callbacks into cpufreq governors are only made from the scheduler if the target CPU of the event is the same as the current CPU. This means there are certain situations where a target CPU may not run the cpufreq governor for some time. One testcase to show this behavior is where a task starts running on CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the system is configured such that the new tasks should receive maximum demand initially, this should result in CPU0 increasing frequency immediately. But because of the above mentioned limitation though, this does not occur. This patch updates the scheduler core to call the cpufreq callbacks for remote CPUs as well. The schedutil, ondemand and conservative governors are updated to process cpufreq utilization update hooks called for remote CPUs where the remote CPU is managed by the cpufreq policy of the local CPU. The intel_pstate driver is updated to always reject remote callbacks. This is tested with couple of usecases (Android: hackbench, recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey board (64 bit octa-core, single policy). Only galleryfling showed minor improvements, while others didn't had much deviation. The reason being that this patch only targets a corner case, where following are required to be true to improve performance and that doesn't happen too often with these tests: - Task is migrated to another CPU. - The task has high demand, and should take the target CPU to higher OPPs. - And the target CPU doesn't call into the cpufreq governor until the next tick. Based on initial work from Steve Muckle. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-28 06:46:38 +00:00
return false;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
if (sg_policy->work_in_progress)
return false;
cpufreq: schedutil: Don't set next_freq to UINT_MAX The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 10:35:24 +00:00
if (unlikely(sg_policy->need_freq_update))
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
return true;
delta_ns = time - sg_policy->last_freq_update_time;
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
return delta_ns >= sg_policy->freq_update_delay_ns;
}
static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
unsigned int next_freq)
{
struct cpufreq_policy *policy = sg_policy->policy;
cpufreq: schedutil: Trace frequency only if it has changed sugov_update_commit() calls trace_cpu_frequency() to record the current CPU frequency if it has not changed in the fast switch case to prevent utilities from getting confused (they may report that the CPU is idle if the frequency has not been recorded for too long, for example). However, that may cause the tracepoint to be triggered quite often for no real reason (if the frequency doesn't change, we will not modify the last update time stamp and governor computations may run again shortly when that happens), so don't do that (arguably, it is done to work around a utilities bug anyway). That allows code duplication in sugov_update_commit() to be reduced somewhat too. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2017-03-22 17:32:47 +00:00
if (sg_policy->next_freq == next_freq)
return;
sg_policy->next_freq = next_freq;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sg_policy->last_freq_update_time = time;
if (policy->fast_switch_enabled) {
next_freq = cpufreq_driver_fast_switch(policy, next_freq);
cpufreq: Return 0 from ->fast_switch() on errors CPUFREQ_ENTRY_INVALID is a special symbol which is used to specify that an entry in the cpufreq table is invalid. But using it outside of the scope of the cpufreq table looks a bit incorrect. We can represent an invalid frequency by writing it as 0 instead if we need. Note that it is already done that way for the return value of the ->get() callback. Lets do the same for ->fast_switch() and not use CPUFREQ_ENTRY_INVALID outside of the scope of cpufreq table. Also update the comment over cpufreq_driver_fast_switch() to clearly mention what this returns. None of the drivers return CPUFREQ_ENTRY_INVALID as of now from ->fast_switch() callback and so we don't need to update any of those. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-08-09 04:51:46 +00:00
if (!next_freq)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
return;
policy->cur = next_freq;
trace_cpu_frequency(next_freq, smp_processor_id());
cpufreq: schedutil: Trace frequency only if it has changed sugov_update_commit() calls trace_cpu_frequency() to record the current CPU frequency if it has not changed in the fast switch case to prevent utilities from getting confused (they may report that the CPU is idle if the frequency has not been recorded for too long, for example). However, that may cause the tracepoint to be triggered quite often for no real reason (if the frequency doesn't change, we will not modify the last update time stamp and governor computations may run again shortly when that happens), so don't do that (arguably, it is done to work around a utilities bug anyway). That allows code duplication in sugov_update_commit() to be reduced somewhat too. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2017-03-22 17:32:47 +00:00
} else {
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sg_policy->work_in_progress = true;
irq_work_queue(&sg_policy->irq_work);
}
}
/**
* get_next_freq - Compute a new frequency for a given cpufreq policy.
cpufreq: schedutil: Pass sg_policy to get_next_freq() get_next_freq() uses sg_cpu only to get sg_policy, which the callers of get_next_freq() already have. Pass sg_policy instead of sg_cpu to get_next_freq(), to make it more efficient. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-02 08:33:21 +00:00
* @sg_policy: schedutil policy object to compute the new frequency for.
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
* @util: Current CPU utilization.
* @max: CPU capacity.
*
* If the utilization is frequency-invariant, choose the new frequency to be
* proportional to it, that is
*
* next_freq = C * max_freq * util / max
*
* Otherwise, approximate the would-be frequency-invariant utilization by
* util_raw * (curr_freq / max_freq) which leads to
*
* next_freq = C * curr_freq * util_raw / max
*
* Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
*
* The lowest driver-supported frequency which is equal or greater than the raw
* next_freq (as calculated above) is returned, subject to policy min/max and
* cpufreq driver limitations.
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
*/
cpufreq: schedutil: Pass sg_policy to get_next_freq() get_next_freq() uses sg_cpu only to get sg_policy, which the callers of get_next_freq() already have. Pass sg_policy instead of sg_cpu to get_next_freq(), to make it more efficient. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-02 08:33:21 +00:00
static unsigned int get_next_freq(struct sugov_policy *sg_policy,
unsigned long util, unsigned long max)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
struct cpufreq_policy *policy = sg_policy->policy;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
unsigned int freq = arch_scale_freq_invariant() ?
policy->cpuinfo.max_freq : policy->cur;
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
freq = (freq + (freq >> 2)) * util / max;
cpufreq: schedutil: Don't set next_freq to UINT_MAX The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 10:35:24 +00:00
if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
return sg_policy->next_freq;
cpufreq: schedutil: Don't set next_freq to UINT_MAX The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 10:35:24 +00:00
sg_policy->need_freq_update = false;
cpufreq: schedutil: move cached_raw_freq to struct sugov_policy cached_raw_freq applies to the entire cpufreq policy and not individual CPUs. Apart from wasting per-cpu memory, it is actually wrong to keep it in struct sugov_cpu as we may end up comparing next_freq with a stale cached_raw_freq of a random CPU. Move cached_raw_freq to struct sugov_policy. Fixes: 5cbea46984d6 (cpufreq: schedutil: map raw required frequency to driver frequency) Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-02 08:33:20 +00:00
sg_policy->cached_raw_freq = freq;
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
return cpufreq_driver_resolve_freq(policy, freq);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
sched/cpufreq: Split utilization signals To be able to treat utilization signals of different scheduling classes in different ways (e.g., CFS signal might be stale while DEADLINE signal is never stale by design) we need to split sugov_cpu::util signal in two: util_cfs and util_dl. This patch does that by also changing sugov_get_util() parameter list. After this change, aggregation of the different signals has to be performed by sugov_get_util() users (so that they can decide what to do with the different signals). Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-5-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:21 +00:00
static void sugov_get_util(struct sugov_cpu *sg_cpu)
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
{
sched/cpufreq: Split utilization signals To be able to treat utilization signals of different scheduling classes in different ways (e.g., CFS signal might be stale while DEADLINE signal is never stale by design) we need to split sugov_cpu::util signal in two: util_cfs and util_dl. This patch does that by also changing sugov_get_util() parameter list. After this change, aggregation of the different signals has to be performed by sugov_get_util() users (so that they can decide what to do with the different signals). Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-5-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:21 +00:00
struct rq *rq = cpu_rq(sg_cpu->cpu);
cpufreq / sched: ignore SMT when determining max cpu capacity PELT does not consider SMT when scaling its utilization values via arch_scale_cpu_capacity(). The value in rq->cpu_capacity_orig does take SMT into consideration though and therefore may be smaller than the utilization reported by PELT. On an Intel i7-3630QM for example rq->cpu_capacity_orig is 589 but util_avg scales up to 1024. This means that a 50% utilized CPU will show up in schedutil as ~86% busy. Fix this by using the same CPU scaling value in schedutil as that which is used by PELT. Signed-off-by: Steve Muckle <smuckle@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-08-26 18:40:47 +00:00
sched/cpufreq: Split utilization signals To be able to treat utilization signals of different scheduling classes in different ways (e.g., CFS signal might be stale while DEADLINE signal is never stale by design) we need to split sugov_cpu::util signal in two: util_cfs and util_dl. This patch does that by also changing sugov_get_util() parameter list. After this change, aggregation of the different signals has to be performed by sugov_get_util() users (so that they can decide what to do with the different signals). Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-5-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:21 +00:00
sg_cpu->max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
sg_cpu->util_cfs = cpu_util_cfs(rq);
sg_cpu->util_dl = cpu_util_dl(rq);
}
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
sched/cpufreq: Split utilization signals To be able to treat utilization signals of different scheduling classes in different ways (e.g., CFS signal might be stale while DEADLINE signal is never stale by design) we need to split sugov_cpu::util signal in two: util_cfs and util_dl. This patch does that by also changing sugov_get_util() parameter list. After this change, aggregation of the different signals has to be performed by sugov_get_util() users (so that they can decide what to do with the different signals). Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-5-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:21 +00:00
static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
{
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
struct rq *rq = cpu_rq(sg_cpu->cpu);
unsigned long util;
if (rq->rt.rt_nr_running) {
util = sg_cpu->max;
} else {
util = sg_cpu->util_dl;
if (rq->cfs.h_nr_running)
util += sg_cpu->util_cfs;
}
sched/cpufreq: Use the DEADLINE utilization signal SCHED_DEADLINE tracks active utilization signal with a per dl_rq variable named running_bw. Make use of that to drive CPU frequency selection: add up FAIR and DEADLINE contribution to get the required CPU capacity to handle both requirements (while RT still selects max frequency). Co-authored-by: Claudio Scordino <claudio@evidence.eu.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-2-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:18 +00:00
/*
* Ideally we would like to set util_dl as min/guaranteed freq and
* util_cfs + util_dl as requested freq. However, cpufreq is not yet
* ready for such an interface. So, we only do the latter for now.
*/
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
return min(util, sg_cpu->max);
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
}
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/**
* sugov_iowait_reset() - Reset the IO boost status of a CPU.
* @sg_cpu: the sugov data for the CPU to boost
* @time: the update time from the caller
* @set_iowait_boost: true if an IO boost has been requested
*
* The IO wait boost of a task is disabled after a tick since the last update
* of a CPU. If a new IO wait boost is requested after more then a tick, then
* we enable the boost starting from the minimum frequency, which improves
* energy efficiency by ignoring sporadic wakeups from IO.
*/
static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
bool set_iowait_boost)
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
{
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
s64 delta_ns = time - sg_cpu->last_update;
cpufreq: schedutil: Fix iowait boost reset A more energy efficient update of the IO wait boosting mechanism has been introduced in: commit a5a0809bc58e ("cpufreq: schedutil: Make iowait boost more energy efficient") where the boost value is expected to be: - doubled at each successive wakeup from IO staring from the minimum frequency supported by a CPU - reset when a CPU is not updated for more then one tick by either disabling the IO wait boost or resetting its value to the minimum frequency if this new update requires an IO boost. This approach is supposed to "ignore" boosting for sporadic wakeups from IO, while still getting the frequency boosted to the maximum to benefit long sequence of wakeup from IO operations. However, these assumptions are not always satisfied. For example, when an IO boosted CPU enters idle for more the one tick and then wakes up after an IO wait, since in sugov_set_iowait_boost() we first check the IOWAIT flag, we keep doubling the iowait boost instead of restarting from the minimum frequency value. This misbehavior could happen mainly on non-shared frequency domains, thus defeating the energy efficiency optimization, but it can also happen on shared frequency domain systems. Let fix this issue in sugov_set_iowait_boost() by: - first check the IO wait boost reset conditions to eventually reset the boost value - then applying the correct IO boost value if required by the caller Fixes: a5a0809bc58e (cpufreq: schedutil: Make iowait boost more energy efficient) Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:53 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/* Reset boost only if a tick has elapsed since last request */
if (delta_ns <= TICK_NSEC)
return false;
cpufreq: schedutil: Fix iowait boost reset A more energy efficient update of the IO wait boosting mechanism has been introduced in: commit a5a0809bc58e ("cpufreq: schedutil: Make iowait boost more energy efficient") where the boost value is expected to be: - doubled at each successive wakeup from IO staring from the minimum frequency supported by a CPU - reset when a CPU is not updated for more then one tick by either disabling the IO wait boost or resetting its value to the minimum frequency if this new update requires an IO boost. This approach is supposed to "ignore" boosting for sporadic wakeups from IO, while still getting the frequency boosted to the maximum to benefit long sequence of wakeup from IO operations. However, these assumptions are not always satisfied. For example, when an IO boosted CPU enters idle for more the one tick and then wakes up after an IO wait, since in sugov_set_iowait_boost() we first check the IOWAIT flag, we keep doubling the iowait boost instead of restarting from the minimum frequency value. This misbehavior could happen mainly on non-shared frequency domains, thus defeating the energy efficiency optimization, but it can also happen on shared frequency domain systems. Let fix this issue in sugov_set_iowait_boost() by: - first check the IO wait boost reset conditions to eventually reset the boost value - then applying the correct IO boost value if required by the caller Fixes: a5a0809bc58e (cpufreq: schedutil: Make iowait boost more energy efficient) Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:53 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
sg_cpu->iowait_boost = set_iowait_boost
? sg_cpu->sg_policy->policy->min : 0;
sg_cpu->iowait_boost_pending = set_iowait_boost;
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
return true;
}
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/**
* sugov_iowait_boost() - Updates the IO boost status of a CPU.
* @sg_cpu: the sugov data for the CPU to boost
* @time: the update time from the caller
* @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
*
* Each time a task wakes up after an IO operation, the CPU utilization can be
* boosted to a certain utilization which doubles at each "frequent and
* successive" wakeup from IO, ranging from the utilization of the minimum
* OPP to the utilization of the maximum OPP.
* To keep doubling, an IO boost has to be requested at least once per tick,
* otherwise we restart from the utilization of the minimum OPP.
*/
static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
unsigned int flags)
{
bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
/* Reset boost if the CPU appears to have been idle enough */
if (sg_cpu->iowait_boost &&
sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
return;
/* Boost only tasks waking up after IO */
if (!set_iowait_boost)
return;
/* Ensure boost doubles only one time at each request */
if (sg_cpu->iowait_boost_pending)
return;
sg_cpu->iowait_boost_pending = true;
/* Double the boost at each request */
if (sg_cpu->iowait_boost) {
sg_cpu->iowait_boost <<= 1;
if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max)
sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
return;
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
}
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/* First wakeup after IO: start with minimum boost */
sg_cpu->iowait_boost = sg_cpu->sg_policy->policy->min;
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
}
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/**
* sugov_iowait_apply() - Apply the IO boost to a CPU.
* @sg_cpu: the sugov data for the cpu to boost
* @time: the update time from the caller
* @util: the utilization to (eventually) boost
* @max: the maximum value the utilization can be boosted to
*
* A CPU running a task which woken up after an IO operation can have its
* utilization boosted to speed up the completion of those IO operations.
* The IO boost value is increased each time a task wakes up from IO, in
* sugov_iowait_apply(), and it's instead decreased by this function,
* each time an increase has not been requested (!iowait_boost_pending).
*
* A CPU which also appears to have been idle for at least one tick has also
* its IO boost utilization reset.
*
* This mechanism is designed to boost high frequently IO waiting tasks, while
* being more conservative on tasks which does sporadic IO operations.
*/
static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
unsigned long *util, unsigned long *max)
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
{
cpufreq: schedutil: Use unsigned int for iowait boost Make iowait_boost and iowait_boost_max as unsigned int since its unit is kHz and this is consistent with struct cpufreq_policy. Also change the local variables in sugov_iowait_boost() to match this. Signed-off-by: Joel Fernandes <joelaf@google.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:26 +00:00
unsigned int boost_util, boost_max;
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/* No boost currently required */
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
if (!sg_cpu->iowait_boost)
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
return;
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/* Reset boost if the CPU appears to have been idle enough */
if (sugov_iowait_reset(sg_cpu, time, false))
return;
/*
* An IO waiting task has just woken up:
* allow to further double the boost value
*/
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
if (sg_cpu->iowait_boost_pending) {
sg_cpu->iowait_boost_pending = false;
} else {
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/*
* Otherwise: reduce the boost value and disable it when we
* reach the minimum.
*/
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
sg_cpu->iowait_boost >>= 1;
if (sg_cpu->iowait_boost < sg_cpu->sg_policy->policy->min) {
sg_cpu->iowait_boost = 0;
return;
}
}
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
/*
* Apply the current boost value: a CPU is boosted only if its current
* utilization is smaller then the current IO boost level.
*/
cpufreq: schedutil: Make iowait boost more energy efficient Currently the iowait_boost feature in schedutil makes the frequency go to max on iowait wakeups. This feature was added to handle a case that Peter described where the throughput of operations involving continuous I/O requests [1] is reduced due to running at a lower frequency, however the lower throughput itself causes utilization to be low and hence causing frequency to be low hence its "stuck". Instead of going to max, its also possible to achieve the same effect by ramping up to max if there are repeated in_iowait wakeups happening. This patch is an attempt to do that. We start from a lower frequency (policy->min) and double the boost for every consecutive iowait update until we reach the maximum iowait boost frequency (iowait_boost_max). I ran a synthetic test (continuous O_DIRECT writes in a loop) on an x86 machine with intel_pstate in passive mode using schedutil. In this test the iowait_boost value ramped from 800MHz to 4GHz in 60ms. The patch achieves the desired improved throughput as the existing behavior. [1] https://patchwork.kernel.org/patch/9735885/ Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-23 15:54:25 +00:00
boost_util = sg_cpu->iowait_boost;
boost_max = sg_cpu->iowait_boost_max;
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
if (*util * boost_max < *max * boost_util) {
*util = boost_util;
*max = boost_max;
}
}
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
#ifdef CONFIG_NO_HZ_COMMON
static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
{
cpufreq: schedutil: Use idle_calls counter of the remote CPU Since the recent remote cpufreq callback work, its possible that a cpufreq update is triggered from a remote CPU. For single policies however, the current code uses the local CPU when trying to determine if the remote sg_cpu entered idle or is busy. This is incorrect. To remedy this, compare with the nohz tick idle_calls counter of the remote CPU. Fixes: 674e75411fc2 (sched: cpufreq: Allow remote cpufreq callbacks) Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Joel Fernandes <joelaf@google.com> Cc: 4.14+ <stable@vger.kernel.org> # 4.14+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-12-21 01:22:45 +00:00
unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
bool ret = idle_calls == sg_cpu->saved_idle_calls;
sg_cpu->saved_idle_calls = idle_calls;
return ret;
}
#else
static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
#endif /* CONFIG_NO_HZ_COMMON */
sched/cpufreq: Rate limits for SCHED_DEADLINE When the SCHED_DEADLINE scheduling class increases the CPU utilization, it should not wait for the rate limit, otherwise it may miss some deadline. Tests using rt-app on Exynos5422 with up to 10 SCHED_DEADLINE tasks have shown reductions of even 10% of deadline misses with a negligible increase of energy consumption (measured through Baylibre Cape). Signed-off-by: Claudio Scordino <claudio@evidence.eu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: linux-pm@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Todd Kjos <tkjos@android.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/1520937340-2755-1-git-send-email-claudio@evidence.eu.com
2018-03-13 10:35:40 +00:00
/*
* Make sugov_should_update_freq() ignore the rate limit when DL
* has increased the utilization.
*/
static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
{
if (cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl)
sg_policy->need_freq_update = true;
}
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
static void sugov_update_single(struct update_util_data *hook, u64 time,
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
unsigned int flags)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
struct sugov_policy *sg_policy = sg_cpu->sg_policy;
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
unsigned long util, max;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
unsigned int next_f;
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
bool busy;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
sugov_iowait_boost(sg_cpu, time, flags);
cpufreq: schedutil: Add iowait boosting Modify the schedutil cpufreq governor to boost the CPU frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to it via cpufreq_update_util(). If that happens, the frequency is set to the maximum during the first update after receiving the SCHED_CPUFREQ_IOWAIT flag and then the boost is reduced by half during each following update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Looks-good-to: Steve Muckle <smuckle@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-09-09 22:00:31 +00:00
sg_cpu->last_update = time;
sched/cpufreq: Rate limits for SCHED_DEADLINE When the SCHED_DEADLINE scheduling class increases the CPU utilization, it should not wait for the rate limit, otherwise it may miss some deadline. Tests using rt-app on Exynos5422 with up to 10 SCHED_DEADLINE tasks have shown reductions of even 10% of deadline misses with a negligible increase of energy consumption (measured through Baylibre Cape). Signed-off-by: Claudio Scordino <claudio@evidence.eu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: linux-pm@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Todd Kjos <tkjos@android.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/1520937340-2755-1-git-send-email-claudio@evidence.eu.com
2018-03-13 10:35:40 +00:00
ignore_dl_rate_limit(sg_cpu, sg_policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
if (!sugov_should_update_freq(sg_policy, time))
return;
cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21 23:08:50 +00:00
busy = sugov_cpu_is_busy(sg_cpu);
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
sugov_get_util(sg_cpu);
max = sg_cpu->max;
util = sugov_aggregate_util(sg_cpu);
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
sugov_iowait_apply(sg_cpu, time, &util, &max);
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
next_f = get_next_freq(sg_policy, util, max);
/*
* Do not reduce the frequency if the CPU has not been idle
* recently, as the reduction is likely to be premature then.
*/
cpufreq: schedutil: Don't set next_freq to UINT_MAX The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 10:35:24 +00:00
if (busy && next_f < sg_policy->next_freq) {
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
next_f = sg_policy->next_freq;
cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq 'cached_raw_freq' is used to get the next frequency quickly but should always be in sync with sg_policy->next_freq. There is a case where it is not and in such cases it should be reset to avoid switching to incorrect frequencies. Consider this case for example: - policy->cur is 1.2 GHz (Max) - New request comes for 780 MHz and we store that in cached_raw_freq. - Based on 780 MHz, we calculate the effective frequency as 800 MHz. - We then see the CPU wasn't idle recently and choose to keep the next freq as 1.2 GHz. - Now we have cached_raw_freq is 780 MHz and sg_policy->next_freq is 1.2 GHz. - Now if the utilization doesn't change in then next request, then the next target frequency will still be 780 MHz and it will match with cached_raw_freq. But we will choose 1.2 GHz instead of 800 MHz here. Fixes: b7eaf1aab9f8 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely) Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: 4.12+ <stable@vger.kernel.org> # 4.12+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-11-08 14:53:55 +00:00
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
/* Reset cached freq as next_freq has changed */
sg_policy->cached_raw_freq = 0;
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
}
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sugov_update_commit(sg_policy, time, next_f);
}
cpufreq: schedutil: use now as reference when aggregating shared policy requests Currently, sugov_next_freq_shared() uses last_freq_update_time as a reference to decide when to start considering CPU contributions as stale. However, since last_freq_update_time is set by the last CPU that issued a frequency transition, this might cause problems in certain cases. In practice, the detection of stale utilization values fails whenever the CPU with such values was the last to update the policy. For example (and please note again that the SCHED_CPUFREQ_RT flag is not the problem here, but only the detection of after how much time that flag has to be considered stale), suppose a policy with 2 CPUs: CPU0 | CPU1 | | RT task scheduled | SCHED_CPUFREQ_RT is set | CPU1->last_update = now | freq transition to max | last_freq_update_time = now | more than TICK_NSEC nsecs | a small CFS wakes up | CPU0->last_update = now1 | delta_ns(CPU0) < TICK_NSEC* | CPU0's util is considered | delta_ns(CPU1) = | last_freq_update_time - | CPU1->last_update = 0 | < TICK_NSEC | CPU1 is still considered | CPU1->SCHED_CPUFREQ_RT is set | we stay at max (until CPU1 | exits from idle) | * delta_ns is actually negative as now1 > last_freq_update_time While last_freq_update_time is a sensible reference for rate limiting, it doesn't seem to be useful for working around stale CPU states. Fix the problem by always considering now (time) as the reference for deciding when CPUs have stale contributions. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-05-03 13:30:48 +00:00
static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
cpufreq: schedutil: map raw required frequency to driver frequency The slow-path frequency transition path is relatively expensive as it requires waking up a thread to do work. Should support be added for remote CPU cpufreq updates that is also expensive since it requires an IPI. These activities should be avoided if they are not necessary. To that end, calculate the actual driver-supported frequency required by the new utilization value in schedutil by using the recently added cpufreq_driver_resolve_freq API. If it is the same as the previously requested driver frequency then there is no need to continue with the update assuming the cpu frequency limits have not changed. This will have additional benefits should the semantics of the rate limit be changed to apply solely to frequency transitions rather than to frequency calculations in schedutil. The last raw required frequency is cached. This allows the driver frequency lookup to be skipped in the event that the new raw required frequency matches the last one, assuming a frequency update has not been forced due to limits changing (indicated by a next_freq value of UINT_MAX, see sugov_should_update_freq). Signed-off-by: Steve Muckle <smuckle@linaro.org> Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-13 20:25:26 +00:00
struct sugov_policy *sg_policy = sg_cpu->sg_policy;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
struct cpufreq_policy *policy = sg_policy->policy;
cpufreq: schedutil: Refactor sugov_next_freq_shared() The loop in sugov_next_freq_shared() contains an if block to skip the loop for the current CPU. This turns out to be an unnecessary conditional in the scheduler's hot-path for every CPU in the policy. It would be better to drop the conditional and make the loop treat all the CPUs in the same way. That would eliminate the need of calling sugov_iowait_boost() at the top of the routine. To keep the code optimized to return early if the current CPU has RT/DL flags set, move the flags check to sugov_update_shared() instead in order to avoid the function call entirely. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-09 04:04:54 +00:00
unsigned long util = 0, max = 1;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
unsigned int j;
for_each_cpu(j, policy->cpus) {
cpufreq: schedutil: Refactor sugov_next_freq_shared() The loop in sugov_next_freq_shared() contains an if block to skip the loop for the current CPU. This turns out to be an unnecessary conditional in the scheduler's hot-path for every CPU in the policy. It would be better to drop the conditional and make the loop treat all the CPUs in the same way. That would eliminate the need of calling sugov_iowait_boost() at the top of the routine. To keep the code optimized to return early if the current CPU has RT/DL flags set, move the flags check to sugov_update_shared() instead in order to avoid the function call entirely. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-09 04:04:54 +00:00
struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
unsigned long j_util, j_max;
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
sugov_get_util(j_sg_cpu);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
j_max = j_sg_cpu->max;
sched/cpufreq: Split utilization signals To be able to treat utilization signals of different scheduling classes in different ways (e.g., CFS signal might be stale while DEADLINE signal is never stale by design) we need to split sugov_cpu::util signal in two: util_cfs and util_dl. This patch does that by also changing sugov_get_util() parameter list. After this change, aggregation of the different signals has to be performed by sugov_get_util() users (so that they can decide what to do with the different signals). Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-5-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:21 +00:00
j_util = sugov_aggregate_util(j_sg_cpu);
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
sugov_iowait_apply(j_sg_cpu, time, &j_util, &j_max);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
if (j_util * max > j_max * util) {
util = j_util;
max = j_max;
}
}
cpufreq: schedutil: Pass sg_policy to get_next_freq() get_next_freq() uses sg_cpu only to get sg_policy, which the callers of get_next_freq() already have. Pass sg_policy instead of sg_cpu to get_next_freq(), to make it more efficient. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-02 08:33:21 +00:00
return get_next_freq(sg_policy, util, max);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
static void
sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
struct sugov_policy *sg_policy = sg_cpu->sg_policy;
unsigned int next_f;
raw_spin_lock(&sg_policy->update_lock);
cpufreq: schedutil: Cleanup and document iowait boost The iowait boosting code has been recently updated to add a progressive boosting behavior which allows to be less aggressive in boosting tasks doing only sporadic IO operations, thus being more energy efficient for example on mobile platforms. The current code is now however a bit convoluted. Some functionalities (e.g. iowait boost reset) are replicated in different paths and their documentation is slightly misaligned. Let's cleanup the code by consolidating all the IO wait boosting related functionality within within few dedicated functions and better define their role: - sugov_iowait_boost: set/increase the IO wait boost of a CPU - sugov_iowait_apply: apply/reduce the IO wait boost of a CPU Both these two function are used at every sugov update and they make use of a unified IO wait boost reset policy provided by: - sugov_iowait_reset: reset/disable the IO wait boost of a CPU if a CPU is not updated for more then one tick This makes possible a cleaner and more self-contained design for the IO wait boosting code since the rest of the sugov update routines, both for single and shared frequency domains, follow the same template: /* Configure IO boost, if required */ sugov_iowait_boost() /* Return here if freq change is in progress or throttled */ /* Collect and aggregate utilization information */ sugov_get_util() sugov_aggregate_util() /* * Add IO boost, if currently enabled, on top of the aggregated * utilization value */ sugov_iowait_apply() As a extra bonus, let's also add the documentation for the new functions and better align the in-code documentation. Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-22 11:07:54 +00:00
sugov_iowait_boost(sg_cpu, time, flags);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sg_cpu->last_update = time;
sched/cpufreq: Rate limits for SCHED_DEADLINE When the SCHED_DEADLINE scheduling class increases the CPU utilization, it should not wait for the rate limit, otherwise it may miss some deadline. Tests using rt-app on Exynos5422 with up to 10 SCHED_DEADLINE tasks have shown reductions of even 10% of deadline misses with a negligible increase of energy consumption (measured through Baylibre Cape). Signed-off-by: Claudio Scordino <claudio@evidence.eu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: linux-pm@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Todd Kjos <tkjos@android.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/1520937340-2755-1-git-send-email-claudio@evidence.eu.com
2018-03-13 10:35:40 +00:00
ignore_dl_rate_limit(sg_cpu, sg_policy);
cpufreq: schedutil: Refactor sugov_next_freq_shared() The loop in sugov_next_freq_shared() contains an if block to skip the loop for the current CPU. This turns out to be an unnecessary conditional in the scheduler's hot-path for every CPU in the policy. It would be better to drop the conditional and make the loop treat all the CPUs in the same way. That would eliminate the need of calling sugov_iowait_boost() at the top of the routine. To keep the code optimized to return early if the current CPU has RT/DL flags set, move the flags check to sugov_update_shared() instead in order to avoid the function call entirely. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-03-09 04:04:54 +00:00
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
if (sugov_should_update_freq(sg_policy, time)) {
cpufreq/schedutil: Rewrite CPUFREQ_RT support Instead of trying to duplicate scheduler state to track if an RT task is running, directly use the scheduler runqueue state for it. This vastly simplifies things and fixes a number of bugs related to sugov and the scheduler getting out of sync wrt this state. As a consequence we not also update the remove cfs/dl state when iterating the shared mask. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-20 15:26:12 +00:00
next_f = sugov_next_freq_shared(sg_cpu, time);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sugov_update_commit(sg_policy, time, next_f);
}
raw_spin_unlock(&sg_policy->update_lock);
}
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
static void sugov_work(struct kthread_work *work)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
mutex_lock(&sg_policy->work_lock);
__cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
CPUFREQ_RELATION_L);
mutex_unlock(&sg_policy->work_lock);
sg_policy->work_in_progress = false;
}
static void sugov_irq_work(struct irq_work *irq_work)
{
struct sugov_policy *sg_policy;
sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
kthread_queue_work(&sg_policy->worker, &sg_policy->work);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
/************************** sysfs interface ************************/
static struct sugov_tunables *global_tunables;
static DEFINE_MUTEX(global_tunables_lock);
static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
{
return container_of(attr_set, struct sugov_tunables, attr_set);
}
static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
{
struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
return sprintf(buf, "%u\n", tunables->rate_limit_us);
}
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
static ssize_t
rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
struct sugov_policy *sg_policy;
unsigned int rate_limit_us;
if (kstrtouint(buf, 10, &rate_limit_us))
return -EINVAL;
tunables->rate_limit_us = rate_limit_us;
list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
return count;
}
static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
static struct attribute *sugov_attributes[] = {
&rate_limit_us.attr,
NULL
};
static struct kobj_type sugov_tunables_ktype = {
.default_attrs = sugov_attributes,
.sysfs_ops = &governor_sysfs_ops,
};
/********************** cpufreq governor interface *********************/
static struct cpufreq_governor schedutil_gov;
static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
{
struct sugov_policy *sg_policy;
sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
if (!sg_policy)
return NULL;
sg_policy->policy = policy;
raw_spin_lock_init(&sg_policy->update_lock);
return sg_policy;
}
static void sugov_policy_free(struct sugov_policy *sg_policy)
{
kfree(sg_policy);
}
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
static int sugov_kthread_create(struct sugov_policy *sg_policy)
{
struct task_struct *thread;
sched/cpufreq: Change the worker kthread to SCHED_DEADLINE Worker kthread needs to be able to change frequency for all other threads. Make it special, just under STOP class. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:20 +00:00
struct sched_attr attr = {
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
.size = sizeof(struct sched_attr),
.sched_policy = SCHED_DEADLINE,
.sched_flags = SCHED_FLAG_SUGOV,
.sched_nice = 0,
.sched_priority = 0,
sched/cpufreq: Change the worker kthread to SCHED_DEADLINE Worker kthread needs to be able to change frequency for all other threads. Make it special, just under STOP class. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:20 +00:00
/*
* Fake (unused) bandwidth; workaround to "fix"
* priority inheritance.
*/
.sched_runtime = 1000000,
.sched_deadline = 10000000,
.sched_period = 10000000,
};
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
struct cpufreq_policy *policy = sg_policy->policy;
int ret;
/* kthread only required for slow path */
if (policy->fast_switch_enabled)
return 0;
kthread_init_work(&sg_policy->work, sugov_work);
kthread_init_worker(&sg_policy->worker);
thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
"sugov:%d",
cpumask_first(policy->related_cpus));
if (IS_ERR(thread)) {
pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
return PTR_ERR(thread);
}
sched/cpufreq: Change the worker kthread to SCHED_DEADLINE Worker kthread needs to be able to change frequency for all other threads. Make it special, just under STOP class. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:20 +00:00
ret = sched_setattr_nocheck(thread, &attr);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
if (ret) {
kthread_stop(thread);
sched/cpufreq: Change the worker kthread to SCHED_DEADLINE Worker kthread needs to be able to change frequency for all other threads. Make it special, just under STOP class. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: alessio.balsini@arm.com Cc: bristot@redhat.com Cc: dietmar.eggemann@arm.com Cc: joelaf@google.com Cc: juri.lelli@redhat.com Cc: mathieu.poirier@linaro.org Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: rjw@rjwysocki.net Cc: rostedt@goodmis.org Cc: tkjos@android.com Cc: tommaso.cucinotta@santannapisa.it Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-04 10:23:20 +00:00
pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
return ret;
}
sg_policy->thread = thread;
Revert "cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily" This reverts commit e2cabe48c20efb174ce0c01190f8b9c5f3ea1d13. Lifting the restriction that the sugov kthread is bound to the policy->related_cpus for a system with a slow switching cpufreq driver, which is able to perform DVFS from any cpu (e.g. cpufreq-dt), is not only not beneficial it also harms Enery-Aware Scheduling (EAS) on systems with asymmetric cpu capacities (e.g. Arm big.LITTLE). The sugov kthread which does the update for the little cpus could potentially run on a big cpu. It could prevent that the big cluster goes into deeper idle states although all the tasks are running on the little cluster. Example: hikey960 w/ 4.16.0-rc6-+ Arm big.LITTLE with per-cluster DVFS root@h960:~# cat /proc/cpuinfo | grep "^CPU part" CPU part : 0xd03 (Cortex-A53, little cpu) CPU part : 0xd03 CPU part : 0xd03 CPU part : 0xd03 CPU part : 0xd09 (Cortex-A73, big cpu) CPU part : 0xd09 CPU part : 0xd09 CPU part : 0xd09 root@h960:/sys/devices/system/cpu/cpufreq# ls policy0 policy4 schedutil root@h960:/sys/devices/system/cpu/cpufreq# cat policy*/related_cpus 0 1 2 3 4 5 6 7 (1) w/o the revert: root@h960:~# ps -eo pid,class,rtprio,pri,psr,comm | awk 'NR == 1 || /sugov/' PID CLS RTPRIO PRI PSR COMMAND 1489 #6 0 140 1 sugov:0 1490 #6 0 140 0 sugov:4 The sugov kthread sugov:4 responsible for policy4 runs on cpu0. (In this case both sugov kthreads run on little cpus). cross policy (cluster) remote callback example: ... migration/1-14 [001] enqueue_task_fair: this_cpu=1 cpu_of(rq)=5 migration/1-14 [001] sugov_update_shared: this_cpu=1 sg_cpu->cpu=5 sg_cpu->sg_policy->policy->related_cpus=4-7 sugov:4-1490 [000] sugov_work: this_cpu=0 sg_cpu->sg_policy->policy->related_cpus=4-7 ... The remote callback (this_cpu=1, target_cpu=5) is executed on cpu=0. (2) w/ the revert: root@h960:~# ps -eo pid,class,rtprio,pri,psr,comm | awk 'NR == 1 || /sugov/' PID CLS RTPRIO PRI PSR COMMAND 1491 #6 0 140 2 sugov:0 1492 #6 0 140 4 sugov:4 The sugov kthread sugov:4 responsible for policy4 runs on cpu4. cross policy (cluster) remote callback example: ... migration/1-14 [001] enqueue_task_fair: this_cpu=1 cpu_of(rq)=7 migration/1-14 [001] sugov_update_shared: this_cpu=1 sg_cpu->cpu=7 sg_cpu->sg_policy->policy->related_cpus=4-7 sugov:4-1492 [004] sugov_work: this_cpu=4 sg_cpu->sg_policy->policy->related_cpus=4-7 ... The remote callback (this_cpu=1, target_cpu=7) is executed on cpu=4. Now the sugov kthread executes again on the policy (cluster) for which the Operating Performance Point (OPP) should be changed. It avoids the problem that an otherwise idle policy (cluster) is running schedutil (the sugov kthread) for another one. Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-08 07:33:40 +00:00
kthread_bind_mask(thread, policy->related_cpus);
cpufreq: schedutil: irq-work and mutex are only used in slow path Execute the irq-work specific initialization/exit code only when the fast path isn't available. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:23 +00:00
init_irq_work(&sg_policy->irq_work, sugov_irq_work);
mutex_init(&sg_policy->work_lock);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
wake_up_process(thread);
return 0;
}
static void sugov_kthread_stop(struct sugov_policy *sg_policy)
{
/* kthread only required for slow path */
if (sg_policy->policy->fast_switch_enabled)
return;
kthread_flush_worker(&sg_policy->worker);
kthread_stop(sg_policy->thread);
cpufreq: schedutil: irq-work and mutex are only used in slow path Execute the irq-work specific initialization/exit code only when the fast path isn't available. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:23 +00:00
mutex_destroy(&sg_policy->work_lock);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
}
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
{
struct sugov_tunables *tunables;
tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
if (tunables) {
gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
if (!have_governor_per_policy())
global_tunables = tunables;
}
return tunables;
}
static void sugov_tunables_free(struct sugov_tunables *tunables)
{
if (!have_governor_per_policy())
global_tunables = NULL;
kfree(tunables);
}
static int sugov_init(struct cpufreq_policy *policy)
{
struct sugov_policy *sg_policy;
struct sugov_tunables *tunables;
int ret = 0;
/* State should be equivalent to EXIT */
if (policy->governor_data)
return -EBUSY;
cpufreq: schedutil: enable fast switch earlier The fast_switch_enabled flag will be used by both sugov_policy_alloc() and sugov_policy_free() with a later patch. Prepare for that by moving the calls to enable and disable it to the beginning of sugov_init() and end of sugov_exit(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:21 +00:00
cpufreq_enable_fast_switch(policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sg_policy = sugov_policy_alloc(policy);
cpufreq: schedutil: enable fast switch earlier The fast_switch_enabled flag will be used by both sugov_policy_alloc() and sugov_policy_free() with a later patch. Prepare for that by moving the calls to enable and disable it to the beginning of sugov_init() and end of sugov_exit(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:21 +00:00
if (!sg_policy) {
ret = -ENOMEM;
goto disable_fast_switch;
}
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
ret = sugov_kthread_create(sg_policy);
if (ret)
goto free_sg_policy;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
mutex_lock(&global_tunables_lock);
if (global_tunables) {
if (WARN_ON(have_governor_per_policy())) {
ret = -EINVAL;
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
goto stop_kthread;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
policy->governor_data = sg_policy;
sg_policy->tunables = global_tunables;
gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
goto out;
}
tunables = sugov_tunables_alloc(sg_policy);
if (!tunables) {
ret = -ENOMEM;
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
goto stop_kthread;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
cpufreq: Use transition_delay_us for legacy governors as well The policy->transition_delay_us field is used only by the schedutil governor currently, and this field describes how fast the driver wants the cpufreq governor to change CPUs frequency. It should rather be a common thing across all governors, as it doesn't have any schedutil dependency here. Create a new helper cpufreq_policy_transition_delay_us() to get the transition delay across all governors. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-19 10:12:42 +00:00
tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
policy->governor_data = sg_policy;
sg_policy->tunables = tunables;
ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
get_governor_parent_kobj(policy), "%s",
schedutil_gov.name);
if (ret)
goto fail;
cpufreq: schedutil: Avoid indented labels Switch to the more common practice of writing labels. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:20 +00:00
out:
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
mutex_unlock(&global_tunables_lock);
return 0;
cpufreq: schedutil: Avoid indented labels Switch to the more common practice of writing labels. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:20 +00:00
fail:
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
policy->governor_data = NULL;
sugov_tunables_free(tunables);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
stop_kthread:
sugov_kthread_stop(sg_policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
mutex_unlock(&global_tunables_lock);
sched/cpufreq/schedutil: Fix error path mutex unlock This patch prevents the 'global_tunables_lock' mutex from being unlocked before being locked. This mutex is not locked if the sugov_kthread_create() function fails. Signed-off-by: Jules Maselbas <jules.maselbas@arm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Chris Redpath <chris.redpath@arm.com> Cc: Dietmar Eggermann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Stephen Kyle <stephen.kyle@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Cc: nd@arm.com Link: http://lkml.kernel.org/r/20180329144301.38419-1-jules.maselbas@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-29 14:43:01 +00:00
free_sg_policy:
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sugov_policy_free(sg_policy);
cpufreq: schedutil: enable fast switch earlier The fast_switch_enabled flag will be used by both sugov_policy_alloc() and sugov_policy_free() with a later patch. Prepare for that by moving the calls to enable and disable it to the beginning of sugov_init() and end of sugov_exit(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:21 +00:00
disable_fast_switch:
cpufreq_disable_fast_switch(policy);
cpufreq: schedutil: Improve prints messages with pr_fmt Prefix print messages with KBUILD_MODNAME, i.e 'cpufreq_schedutil: '. This helps to keep similar formatting for all the print messages particular to a file and identify those easily in kernel logs. Its already done this way for rest of the governors. Along with that, remove the (now) redundant bits from a print message. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-05-18 12:25:28 +00:00
pr_err("initialization failed (error %d)\n", ret);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
return ret;
}
cpufreq: governor: Get rid of governor events The design of the cpufreq governor API is not very straightforward, as struct cpufreq_governor provides only one callback to be invoked from different code paths for different purposes. The purpose it is invoked for is determined by its second "event" argument, causing it to act as a "callback multiplexer" of sorts. Unfortunately, that leads to extra complexity in governors, some of which implement the ->governor() callback as a switch statement that simply checks the event argument and invokes a separate function to handle that specific event. That extra complexity can be eliminated by replacing the all-purpose ->governor() callback with a family of callbacks to carry out specific governor operations: initialization and exit, start and stop and policy limits updates. That also turns out to reduce the code size too, so do it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-06-02 21:24:15 +00:00
static void sugov_exit(struct cpufreq_policy *policy)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_policy *sg_policy = policy->governor_data;
struct sugov_tunables *tunables = sg_policy->tunables;
unsigned int count;
mutex_lock(&global_tunables_lock);
count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
policy->governor_data = NULL;
if (!count)
sugov_tunables_free(tunables);
mutex_unlock(&global_tunables_lock);
cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task If slow path frequency changes are conducted in a SCHED_OTHER context then they may be delayed for some amount of time, including indefinitely, when real time or deadline activity is taking place. Move the slow path to a real time kernel thread. In the future the thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set to 50 for now. Hackbench results on ARM Exynos, dual core A15 platform for 10 iterations: $ hackbench -s 100 -l 100 -g 10 -f 20 Before After --------------------------------- 1.808 1.603 1.847 1.251 2.229 1.590 1.952 1.600 1.947 1.257 1.925 1.627 2.694 1.620 1.258 1.621 1.919 1.632 1.250 1.240 Average: 1.8829 1.5041 Based on initial work by Steve Muckle. Signed-off-by: Steve Muckle <smuckle.linux@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:22 +00:00
sugov_kthread_stop(sg_policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
sugov_policy_free(sg_policy);
cpufreq: schedutil: enable fast switch earlier The fast_switch_enabled flag will be used by both sugov_policy_alloc() and sugov_policy_free() with a later patch. Prepare for that by moving the calls to enable and disable it to the beginning of sugov_init() and end of sugov_exit(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:21 +00:00
cpufreq_disable_fast_switch(policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
static int sugov_start(struct cpufreq_policy *policy)
{
struct sugov_policy *sg_policy = policy->governor_data;
unsigned int cpu;
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
sg_policy->last_freq_update_time = 0;
cpufreq: schedutil: Don't set next_freq to UINT_MAX The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 10:35:24 +00:00
sg_policy->next_freq = 0;
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
sg_policy->work_in_progress = false;
sg_policy->need_freq_update = false;
sg_policy->cached_raw_freq = 0;
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
for_each_cpu(cpu, policy->cpus) {
struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start() sugov_start() only initializes struct sugov_cpu per-CPU structures for shared policies, but it should do that for single-CPU policies too. That in particular makes the IO-wait boost mechanism work in the cases when cpufreq policies correspond to individual CPUs. Fixes: 21ca6d2c52f8 (cpufreq: schedutil: Add iowait boosting) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
2017-03-19 13:30:02 +00:00
memset(sg_cpu, 0, sizeof(*sg_cpu));
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
sg_cpu->cpu = cpu;
sg_cpu->sg_policy = sg_policy;
sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() race With a shared policy in place, when one of the CPUs in the policy is hotplugged out and then brought back online, sugov_stop() and sugov_start() are called in order. sugov_stop() removes utilization hooks for each CPU in the policy and does nothing else in the for_each_cpu() loop. sugov_start() on the other hand iterates through the CPUs in the policy and re-initializes the per-cpu structure _and_ adds the utilization hook. This implies that the scheduler is allowed to invoke a CPU's utilization update hook when the rest of the per-cpu structures have yet to be re-inited. Apart from some strange values in tracepoints this doesn't cause a problem, but if we do end up accessing a pointer from the per-cpu sugov_cpu structure somewhere in the sugov_update_shared() path, we will likely see crashes since the memset for another CPU in the policy is free to race with sugov_update_shared from the CPU that is ready to go. So let's fix this now to first init all per-cpu structures, and then add the per-cpu utilization update hooks all at once. Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-06 17:53:20 +00:00
}
for_each_cpu(cpu, policy->cpus) {
struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start() sugov_start() only initializes struct sugov_cpu per-CPU structures for shared policies, but it should do that for single-CPU policies too. That in particular makes the IO-wait boost mechanism work in the cases when cpufreq policies correspond to individual CPUs. Fixes: 21ca6d2c52f8 (cpufreq: schedutil: Add iowait boosting) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
2017-03-19 13:30:02 +00:00
cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
policy_is_shared(policy) ?
sugov_update_shared :
sugov_update_single);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
return 0;
}
cpufreq: governor: Get rid of governor events The design of the cpufreq governor API is not very straightforward, as struct cpufreq_governor provides only one callback to be invoked from different code paths for different purposes. The purpose it is invoked for is determined by its second "event" argument, causing it to act as a "callback multiplexer" of sorts. Unfortunately, that leads to extra complexity in governors, some of which implement the ->governor() callback as a switch statement that simply checks the event argument and invokes a separate function to handle that specific event. That extra complexity can be eliminated by replacing the all-purpose ->governor() callback with a family of callbacks to carry out specific governor operations: initialization and exit, start and stop and policy limits updates. That also turns out to reduce the code size too, so do it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-06-02 21:24:15 +00:00
static void sugov_stop(struct cpufreq_policy *policy)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_policy *sg_policy = policy->governor_data;
unsigned int cpu;
for_each_cpu(cpu, policy->cpus)
cpufreq_remove_update_util_hook(cpu);
synchronize_sched();
cpufreq: schedutil: irq-work and mutex are only used in slow path Execute the irq-work specific initialization/exit code only when the fast path isn't available. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-11-15 08:23:23 +00:00
if (!policy->fast_switch_enabled) {
irq_work_sync(&sg_policy->irq_work);
kthread_cancel_work_sync(&sg_policy->work);
}
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
}
cpufreq: governor: Get rid of governor events The design of the cpufreq governor API is not very straightforward, as struct cpufreq_governor provides only one callback to be invoked from different code paths for different purposes. The purpose it is invoked for is determined by its second "event" argument, causing it to act as a "callback multiplexer" of sorts. Unfortunately, that leads to extra complexity in governors, some of which implement the ->governor() callback as a switch statement that simply checks the event argument and invokes a separate function to handle that specific event. That extra complexity can be eliminated by replacing the all-purpose ->governor() callback with a family of callbacks to carry out specific governor operations: initialization and exit, start and stop and policy limits updates. That also turns out to reduce the code size too, so do it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-06-02 21:24:15 +00:00
static void sugov_limits(struct cpufreq_policy *policy)
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
{
struct sugov_policy *sg_policy = policy->governor_data;
if (!policy->fast_switch_enabled) {
mutex_lock(&sg_policy->work_lock);
cpufreq: governor: Create cpufreq_policy_apply_limits() Create a new helper to avoid code duplication across governors. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-05-18 12:25:31 +00:00
cpufreq_policy_apply_limits(policy);
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
mutex_unlock(&sg_policy->work_lock);
}
sg_policy->need_freq_update = true;
}
static struct cpufreq_governor schedutil_gov = {
sched: Clean up and harmonize the coding style of the scheduler code base A good number of small style inconsistencies have accumulated in the scheduler core, so do a pass over them to harmonize all these details: - fix speling in comments, - use curly braces for multi-line statements, - remove unnecessary parentheses from integer literals, - capitalize consistently, - remove stray newlines, - add comments where necessary, - remove invalid/unnecessary comments, - align structure definitions and other data types vertically, - add missing newlines for increased readability, - fix vertical tabulation where it's misaligned, - harmonize preprocessor conditional block labeling and vertical alignment, - remove line-breaks where they uglify the code, - add newline after local variable definitions, No change in functionality: md5: 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.before.asm 1191fa0a890cfa8132156d2959d7e9e2 built-in.o.after.asm Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-03 13:01:12 +00:00
.name = "schedutil",
.owner = THIS_MODULE,
.dynamic_switching = true,
.init = sugov_init,
.exit = sugov_exit,
.start = sugov_start,
.stop = sugov_stop,
.limits = sugov_limits,
cpufreq: schedutil: New governor based on scheduler utilization data Add a new cpufreq scaling governor, called "schedutil", that uses scheduler-provided CPU utilization information as input for making its decisions. Doing that is possible after commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) that introduced cpufreq_update_util() called by the scheduler on utilization changes (from CFS) and RT/DL task status updates. In particular, CPU frequency scaling decisions may be based on the the utilization data passed to cpufreq_update_util() by CFS. The new governor is relatively simple. The frequency selection formula used by it depends on whether or not the utilization is frequency-invariant. In the frequency-invariant case the new CPU frequency is given by next_freq = 1.25 * max_freq * util / max where util and max are the last two arguments of cpufreq_update_util(). In turn, if util is not frequency-invariant, the maximum frequency in the above formula is replaced with the current frequency of the CPU: next_freq = 1.25 * curr_freq * util / max The coefficient 1.25 corresponds to the frequency tipping point at (util / max) = 0.8. All of the computations are carried out in the utilization update handlers provided by the new governor. One of those handlers is used for cpufreq policies shared between multiple CPUs and the other one is for policies with one CPU only (and therefore it doesn't need to use any extra synchronization means). The governor supports fast frequency switching if that is supported by the cpufreq driver in use and possible for the given policy. In the fast switching case, all operations of the governor take place in its utilization update handlers. If fast switching cannot be used, the frequency switch operations are carried out with the help of a work item which only calls __cpufreq_driver_target() (under a mutex) to trigger a frequency update (to a value already computed beforehand in one of the utilization update handlers). Currently, the governor treats all of the RT and DL tasks as "unknown utilization" and sets the frequency to the allowed maximum when updated from the RT or DL sched classes. That heavy-handed approach should be replaced with something more subtle and specifically targeted at RT and DL tasks. The governor shares some tunables management code with the "ondemand" and "conservative" governors and uses some common definitions from cpufreq_governor.h, but apart from that it is stand-alone. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2016-04-01 23:09:12 +00:00
};
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
struct cpufreq_governor *cpufreq_default_governor(void)
{
return &schedutil_gov;
}
#endif
cpufreq / sched: Pass flags to cpufreq_update_util() It is useful to know the reason why cpufreq_update_util() has just been called and that can be passed as flags to cpufreq_update_util() and to the ->func() callback in struct update_util_data. However, doing that in addition to passing the util and max arguments they already take would be clumsy, so avoid it. Instead, use the observation that the schedutil governor is part of the scheduler proper, so it can access scheduler data directly. This allows the util and max arguments of cpufreq_update_util() and the ->func() callback in struct update_util_data to be replaced with a flags one, but schedutil has to be modified to follow. Thus make the schedutil governor obtain the CFS utilization information from the scheduler and use the "RT" and "DL" flags instead of the special utilization value of ULONG_MAX to track updates from the RT and DL sched classes. Make it non-modular too to avoid having to export scheduler variables to modules at large. Next, update all of the other users of cpufreq_update_util() and the ->func() callback in struct update_util_data accordingly. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-08-16 20:14:55 +00:00
static int __init sugov_register(void)
{
return cpufreq_register_governor(&schedutil_gov);
}
fs_initcall(sugov_register);
Reference in New Issue Copy Permalink