forked from Minki/linux
Merge branches 'pm-devfreq', 'powercap' and 'pm-docs'
* pm-devfreq: PM / devfreq: Get rid of some doc warnings PM / devfreq: Fix handling dev_pm_qos_remove_request result PM / devfreq: Fix a typo in a comment PM / devfreq: Change to DEVFREQ_GOV_UPDATE_INTERVAL event name PM / devfreq: Remove unneeded extern keyword PM / devfreq: Use constant name of userspace governor * powercap: powercap: idle_inject: Replace zero-length array with flexible-array member * pm-docs: docs: cpu-freq: convert cpufreq-stats.txt to ReST docs: cpu-freq: convert cpu-drivers.txt to ReST docs: cpu-freq: convert core.txt to ReST docs: cpu-freq: convert index.txt to ReST docs: cpufreq: fix a broken reference Documentation: cpufreq: Move legacy driver documentation
This commit is contained in:
Rafael J. Wysocki
commit
2409000a0c
274
Documentation/admin-guide/pm/cpufreq_drivers.rst
Normal file
274
Documentation/admin-guide/pm/cpufreq_drivers.rst
Normal file
@ -0,0 +1,274 @@
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
=======================================================
|
||||
Legacy Documentation of CPU Performance Scaling Drivers
|
||||
=======================================================
|
||||
|
||||
Included below are historic documents describing assorted
|
||||
:doc:`CPU performance scaling <cpufreq>` drivers. They are reproduced verbatim,
|
||||
with the original white space formatting and indentation preserved, except for
|
||||
the added leading space character in every line of text.
|
||||
|
||||
|
||||
AMD PowerNow! Drivers
|
||||
=====================
|
||||
|
||||
::
|
||||
|
||||
PowerNow! and Cool'n'Quiet are AMD names for frequency
|
||||
management capabilities in AMD processors. As the hardware
|
||||
implementation changes in new generations of the processors,
|
||||
there is a different cpu-freq driver for each generation.
|
||||
|
||||
Note that the driver's will not load on the "wrong" hardware,
|
||||
so it is safe to try each driver in turn when in doubt as to
|
||||
which is the correct driver.
|
||||
|
||||
Note that the functionality to change frequency (and voltage)
|
||||
is not available in all processors. The drivers will refuse
|
||||
to load on processors without this capability. The capability
|
||||
is detected with the cpuid instruction.
|
||||
|
||||
The drivers use BIOS supplied tables to obtain frequency and
|
||||
voltage information appropriate for a particular platform.
|
||||
Frequency transitions will be unavailable if the BIOS does
|
||||
not supply these tables.
|
||||
|
||||
6th Generation: powernow-k6
|
||||
|
||||
7th Generation: powernow-k7: Athlon, Duron, Geode.
|
||||
|
||||
8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron.
|
||||
Documentation on this functionality in 8th generation processors
|
||||
is available in the "BIOS and Kernel Developer's Guide", publication
|
||||
26094, in chapter 9, available for download from www.amd.com.
|
||||
|
||||
BIOS supplied data, for powernow-k7 and for powernow-k8, may be
|
||||
from either the PSB table or from ACPI objects. The ACPI support
|
||||
is only available if the kernel config sets CONFIG_ACPI_PROCESSOR.
|
||||
The powernow-k8 driver will attempt to use ACPI if so configured,
|
||||
and fall back to PST if that fails.
|
||||
The powernow-k7 driver will try to use the PSB support first, and
|
||||
fall back to ACPI if the PSB support fails. A module parameter,
|
||||
acpi_force, is provided to force ACPI support to be used instead
|
||||
of PSB support.
|
||||
|
||||
|
||||
``cpufreq-nforce2``
|
||||
===================
|
||||
|
||||
::
|
||||
|
||||
The cpufreq-nforce2 driver changes the FSB on nVidia nForce2 platforms.
|
||||
|
||||
This works better than on other platforms, because the FSB of the CPU
|
||||
can be controlled independently from the PCI/AGP clock.
|
||||
|
||||
The module has two options:
|
||||
|
||||
fid: multiplier * 10 (for example 8.5 = 85)
|
||||
min_fsb: minimum FSB
|
||||
|
||||
If not set, fid is calculated from the current CPU speed and the FSB.
|
||||
min_fsb defaults to FSB at boot time - 50 MHz.
|
||||
|
||||
IMPORTANT: The available range is limited downwards!
|
||||
Also the minimum available FSB can differ, for systems
|
||||
booting with 200 MHz, 150 should always work.
|
||||
|
||||
|
||||
``pcc-cpufreq``
|
||||
===============
|
||||
|
||||
::
|
||||
|
||||
/*
|
||||
* pcc-cpufreq.txt - PCC interface documentation
|
||||
*
|
||||
* Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
|
||||
* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
|
||||
* Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
|
||||
*/
|
||||
|
||||
|
||||
Processor Clocking Control Driver
|
||||
---------------------------------
|
||||
|
||||
Contents:
|
||||
---------
|
||||
1. Introduction
|
||||
1.1 PCC interface
|
||||
1.1.1 Get Average Frequency
|
||||
1.1.2 Set Desired Frequency
|
||||
1.2 Platforms affected
|
||||
2. Driver and /sys details
|
||||
2.1 scaling_available_frequencies
|
||||
2.2 cpuinfo_transition_latency
|
||||
2.3 cpuinfo_cur_freq
|
||||
2.4 related_cpus
|
||||
3. Caveats
|
||||
|
||||
1. Introduction:
|
||||
----------------
|
||||
Processor Clocking Control (PCC) is an interface between the platform
|
||||
firmware and OSPM. It is a mechanism for coordinating processor
|
||||
performance (ie: frequency) between the platform firmware and the OS.
|
||||
|
||||
The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC
|
||||
interface.
|
||||
|
||||
OS utilizes the PCC interface to inform platform firmware what frequency the
|
||||
OS wants for a logical processor. The platform firmware attempts to achieve
|
||||
the requested frequency. If the request for the target frequency could not be
|
||||
satisfied by platform firmware, then it usually means that power budget
|
||||
conditions are in place, and "power capping" is taking place.
|
||||
|
||||
1.1 PCC interface:
|
||||
------------------
|
||||
The complete PCC specification is available here:
|
||||
https://acpica.org/sites/acpica/files/Processor-Clocking-Control-v1p0.pdf
|
||||
|
||||
PCC relies on a shared memory region that provides a channel for communication
|
||||
between the OS and platform firmware. PCC also implements a "doorbell" that
|
||||
is used by the OS to inform the platform firmware that a command has been
|
||||
sent.
|
||||
|
||||
The ACPI PCCH() method is used to discover the location of the PCC shared
|
||||
memory region. The shared memory region header contains the "command" and
|
||||
"status" interface. PCCH() also contains details on how to access the platform
|
||||
doorbell.
|
||||
|
||||
The following commands are supported by the PCC interface:
|
||||
* Get Average Frequency
|
||||
* Set Desired Frequency
|
||||
|
||||
The ACPI PCCP() method is implemented for each logical processor and is
|
||||
used to discover the offsets for the input and output buffers in the shared
|
||||
memory region.
|
||||
|
||||
When PCC mode is enabled, the platform will not expose processor performance
|
||||
or throttle states (_PSS, _TSS and related ACPI objects) to OSPM. Therefore,
|
||||
the native P-state driver (such as acpi-cpufreq for Intel, powernow-k8 for
|
||||
AMD) will not load.
|
||||
|
||||
However, OSPM remains in control of policy. The governor (eg: "ondemand")
|
||||
computes the required performance for each processor based on server workload.
|
||||
The PCC driver fills in the command interface, and the input buffer and
|
||||
communicates the request to the platform firmware. The platform firmware is
|
||||
responsible for delivering the requested performance.
|
||||
|
||||
Each PCC command is "global" in scope and can affect all the logical CPUs in
|
||||
the system. Therefore, PCC is capable of performing "group" updates. With PCC
|
||||
the OS is capable of getting/setting the frequency of all the logical CPUs in
|
||||
the system with a single call to the BIOS.
|
||||
|
||||
1.1.1 Get Average Frequency:
|
||||
----------------------------
|
||||
This command is used by the OSPM to query the running frequency of the
|
||||
processor since the last time this command was completed. The output buffer
|
||||
indicates the average unhalted frequency of the logical processor expressed as
|
||||
a percentage of the nominal (ie: maximum) CPU frequency. The output buffer
|
||||
also signifies if the CPU frequency is limited by a power budget condition.
|
||||
|
||||
1.1.2 Set Desired Frequency:
|
||||
----------------------------
|
||||
This command is used by the OSPM to communicate to the platform firmware the
|
||||
desired frequency for a logical processor. The output buffer is currently
|
||||
ignored by OSPM. The next invocation of "Get Average Frequency" will inform
|
||||
OSPM if the desired frequency was achieved or not.
|
||||
|
||||
1.2 Platforms affected:
|
||||
-----------------------
|
||||
The PCC driver will load on any system where the platform firmware:
|
||||
* supports the PCC interface, and the associated PCCH() and PCCP() methods
|
||||
* assumes responsibility for managing the hardware clocking controls in order
|
||||
to deliver the requested processor performance
|
||||
|
||||
Currently, certain HP ProLiant platforms implement the PCC interface. On those
|
||||
platforms PCC is the "default" choice.
|
||||
|
||||
However, it is possible to disable this interface via a BIOS setting. In
|
||||
such an instance, as is also the case on platforms where the PCC interface
|
||||
is not implemented, the PCC driver will fail to load silently.
|
||||
|
||||
2. Driver and /sys details:
|
||||
---------------------------
|
||||
When the driver loads, it merely prints the lowest and the highest CPU
|
||||
frequencies supported by the platform firmware.
|
||||
|
||||
The PCC driver loads with a message such as:
|
||||
pcc-cpufreq: (v1.00.00) driver loaded with frequency limits: 1600 MHz, 2933
|
||||
MHz
|
||||
|
||||
This means that the OPSM can request the CPU to run at any frequency in
|
||||
between the limits (1600 MHz, and 2933 MHz) specified in the message.
|
||||
|
||||
Internally, there is no need for the driver to convert the "target" frequency
|
||||
to a corresponding P-state.
|
||||
|
||||
The VERSION number for the driver will be of the format v.xy.ab.
|
||||
eg: 1.00.02
|
||||
----- --
|
||||
| |
|
||||
| -- this will increase with bug fixes/enhancements to the driver
|
||||
|-- this is the version of the PCC specification the driver adheres to
|
||||
|
||||
|
||||
The following is a brief discussion on some of the fields exported via the
|
||||
/sys filesystem and how their values are affected by the PCC driver:
|
||||
|
||||
2.1 scaling_available_frequencies:
|
||||
----------------------------------
|
||||
scaling_available_frequencies is not created in /sys. No intermediate
|
||||
frequencies need to be listed because the BIOS will try to achieve any
|
||||
frequency, within limits, requested by the governor. A frequency does not have
|
||||
to be strictly associated with a P-state.
|
||||
|
||||
2.2 cpuinfo_transition_latency:
|
||||
-------------------------------
|
||||
The cpuinfo_transition_latency field is 0. The PCC specification does
|
||||
not include a field to expose this value currently.
|
||||
|
||||
2.3 cpuinfo_cur_freq:
|
||||
---------------------
|
||||
A) Often cpuinfo_cur_freq will show a value different than what is declared
|
||||
in the scaling_available_frequencies or scaling_cur_freq, or scaling_max_freq.
|
||||
This is due to "turbo boost" available on recent Intel processors. If certain
|
||||
conditions are met the BIOS can achieve a slightly higher speed than requested
|
||||
by OSPM. An example:
|
||||
|
||||
scaling_cur_freq : 2933000
|
||||
cpuinfo_cur_freq : 3196000
|
||||
|
||||
B) There is a round-off error associated with the cpuinfo_cur_freq value.
|
||||
Since the driver obtains the current frequency as a "percentage" (%) of the
|
||||
nominal frequency from the BIOS, sometimes, the values displayed by
|
||||
scaling_cur_freq and cpuinfo_cur_freq may not match. An example:
|
||||
|
||||
scaling_cur_freq : 1600000
|
||||
cpuinfo_cur_freq : 1583000
|
||||
|
||||
In this example, the nominal frequency is 2933 MHz. The driver obtains the
|
||||
current frequency, cpuinfo_cur_freq, as 54% of the nominal frequency:
|
||||
|
||||
54% of 2933 MHz = 1583 MHz
|
||||
|
||||
Nominal frequency is the maximum frequency of the processor, and it usually
|
||||
corresponds to the frequency of the P0 P-state.
|
||||
|
||||
2.4 related_cpus:
|
||||
-----------------
|
||||
The related_cpus field is identical to affected_cpus.
|
||||
|
||||
affected_cpus : 4
|
||||
related_cpus : 4
|
||||
|
||||
Currently, the PCC driver does not evaluate _PSD. The platforms that support
|
||||
PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination
|
||||
to ensure that the same frequency is requested of all dependent CPUs.
|
||||
|
||||
3. Caveats:
|
||||
-----------
|
||||
The "cpufreq_stats" module in its present form cannot be loaded and
|
||||
expected to work with the PCC driver. Since the "cpufreq_stats" module
|
||||
provides information wrt each P-state, it is not applicable to the PCC driver.
|
||||
@ -11,4 +11,5 @@ Working-State Power Management
|
||||
intel_idle
|
||||
cpufreq
|
||||
intel_pstate
|
||||
cpufreq_drivers
|
||||
intel_epb
|
||||
|
||||
@ -1,38 +0,0 @@
|
||||
|
||||
PowerNow! and Cool'n'Quiet are AMD names for frequency
|
||||
management capabilities in AMD processors. As the hardware
|
||||
implementation changes in new generations of the processors,
|
||||
there is a different cpu-freq driver for each generation.
|
||||
|
||||
Note that the driver's will not load on the "wrong" hardware,
|
||||
so it is safe to try each driver in turn when in doubt as to
|
||||
which is the correct driver.
|
||||
|
||||
Note that the functionality to change frequency (and voltage)
|
||||
is not available in all processors. The drivers will refuse
|
||||
to load on processors without this capability. The capability
|
||||
is detected with the cpuid instruction.
|
||||
|
||||
The drivers use BIOS supplied tables to obtain frequency and
|
||||
voltage information appropriate for a particular platform.
|
||||
Frequency transitions will be unavailable if the BIOS does
|
||||
not supply these tables.
|
||||
|
||||
6th Generation: powernow-k6
|
||||
|
||||
7th Generation: powernow-k7: Athlon, Duron, Geode.
|
||||
|
||||
8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron.
|
||||
Documentation on this functionality in 8th generation processors
|
||||
is available in the "BIOS and Kernel Developer's Guide", publication
|
||||
26094, in chapter 9, available for download from www.amd.com.
|
||||
|
||||
BIOS supplied data, for powernow-k7 and for powernow-k8, may be
|
||||
from either the PSB table or from ACPI objects. The ACPI support
|
||||
is only available if the kernel config sets CONFIG_ACPI_PROCESSOR.
|
||||
The powernow-k8 driver will attempt to use ACPI if so configured,
|
||||
and fall back to PST if that fails.
|
||||
The powernow-k7 driver will try to use the PSB support first, and
|
||||
fall back to ACPI if the PSB support fails. A module parameter,
|
||||
acpi_force, is provided to force ACPI support to be used instead
|
||||
of PSB support.
|
||||
@ -1,31 +1,23 @@
|
||||
CPU frequency and voltage scaling code in the Linux(TM) kernel
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
=============================================================
|
||||
General description of the CPUFreq core and CPUFreq notifiers
|
||||
=============================================================
|
||||
|
||||
L i n u x C P U F r e q
|
||||
Authors:
|
||||
- Dominik Brodowski <linux@brodo.de>
|
||||
- David Kimdon <dwhedon@debian.org>
|
||||
- Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
||||
- Viresh Kumar <viresh.kumar@linaro.org>
|
||||
|
||||
C P U F r e q C o r e
|
||||
.. Contents:
|
||||
|
||||
|
||||
Dominik Brodowski <linux@brodo.de>
|
||||
David Kimdon <dwhedon@debian.org>
|
||||
Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
||||
Viresh Kumar <viresh.kumar@linaro.org>
|
||||
|
||||
|
||||
|
||||
Clock scaling allows you to change the clock speed of the CPUs on the
|
||||
fly. This is a nice method to save battery power, because the lower
|
||||
the clock speed, the less power the CPU consumes.
|
||||
|
||||
|
||||
Contents:
|
||||
---------
|
||||
1. CPUFreq core and interfaces
|
||||
2. CPUFreq notifiers
|
||||
3. CPUFreq Table Generation with Operating Performance Point (OPP)
|
||||
1. CPUFreq core and interfaces
|
||||
2. CPUFreq notifiers
|
||||
3. CPUFreq Table Generation with Operating Performance Point (OPP)
|
||||
|
||||
1. General Information
|
||||
=======================
|
||||
======================
|
||||
|
||||
The CPUFreq core code is located in drivers/cpufreq/cpufreq.c. This
|
||||
cpufreq code offers a standardized interface for the CPUFreq
|
||||
@ -63,7 +55,7 @@ The phase is specified in the second argument to the notifier. The phase is
|
||||
CPUFREQ_CREATE_POLICY when the policy is first created and it is
|
||||
CPUFREQ_REMOVE_POLICY when the policy is removed.
|
||||
|
||||
The third argument, a void *pointer, points to a struct cpufreq_policy
|
||||
The third argument, a ``void *pointer``, points to a struct cpufreq_policy
|
||||
consisting of several values, including min, max (the lower and upper
|
||||
frequencies (in kHz) of the new policy).
|
||||
|
||||
@ -80,10 +72,13 @@ CPUFREQ_POSTCHANGE.
|
||||
|
||||
The third argument is a struct cpufreq_freqs with the following
|
||||
values:
|
||||
cpu - number of the affected CPU
|
||||
old - old frequency
|
||||
new - new frequency
|
||||
flags - flags of the cpufreq driver
|
||||
|
||||
===== ===========================
|
||||
cpu number of the affected CPU
|
||||
old old frequency
|
||||
new new frequency
|
||||
flags flags of the cpufreq driver
|
||||
===== ===========================
|
||||
|
||||
3. CPUFreq Table Generation with Operating Performance Point (OPP)
|
||||
==================================================================
|
||||
@ -94,9 +89,12 @@ dev_pm_opp_init_cpufreq_table -
|
||||
the OPP layer's internal information about the available frequencies
|
||||
into a format readily providable to cpufreq.
|
||||
|
||||
WARNING: Do not use this function in interrupt context.
|
||||
.. Warning::
|
||||
|
||||
Do not use this function in interrupt context.
|
||||
|
||||
Example::
|
||||
|
||||
Example:
|
||||
soc_pm_init()
|
||||
{
|
||||
/* Do things */
|
||||
@ -106,7 +104,10 @@ dev_pm_opp_init_cpufreq_table -
|
||||
/* Do other things */
|
||||
}
|
||||
|
||||
NOTE: This function is available only if CONFIG_CPU_FREQ is enabled in
|
||||
addition to CONFIG_PM_OPP.
|
||||
.. note::
|
||||
|
||||
dev_pm_opp_free_cpufreq_table - Free up the table allocated by dev_pm_opp_init_cpufreq_table
|
||||
This function is available only if CONFIG_CPU_FREQ is enabled in
|
||||
addition to CONFIG_PM_OPP.
|
||||
|
||||
dev_pm_opp_free_cpufreq_table
|
||||
Free up the table allocated by dev_pm_opp_init_cpufreq_table
|
||||
@ -1,35 +1,27 @@
|
||||
CPU frequency and voltage scaling code in the Linux(TM) kernel
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
===============================================
|
||||
How to Implement a new CPUFreq Processor Driver
|
||||
===============================================
|
||||
|
||||
Authors:
|
||||
|
||||
|
||||
L i n u x C P U F r e q
|
||||
- Dominik Brodowski <linux@brodo.de>
|
||||
- Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
||||
- Viresh Kumar <viresh.kumar@linaro.org>
|
||||
|
||||
C P U D r i v e r s
|
||||
.. Contents
|
||||
|
||||
- information for developers -
|
||||
|
||||
|
||||
Dominik Brodowski <linux@brodo.de>
|
||||
Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
||||
Viresh Kumar <viresh.kumar@linaro.org>
|
||||
|
||||
|
||||
|
||||
Clock scaling allows you to change the clock speed of the CPUs on the
|
||||
fly. This is a nice method to save battery power, because the lower
|
||||
the clock speed, the less power the CPU consumes.
|
||||
|
||||
|
||||
Contents:
|
||||
---------
|
||||
1. What To Do?
|
||||
1.1 Initialization
|
||||
1.2 Per-CPU Initialization
|
||||
1.3 verify
|
||||
1.4 target/target_index or setpolicy?
|
||||
1.5 target/target_index
|
||||
1.6 setpolicy
|
||||
1.7 get_intermediate and target_intermediate
|
||||
2. Frequency Table Helpers
|
||||
1. What To Do?
|
||||
1.1 Initialization
|
||||
1.2 Per-CPU Initialization
|
||||
1.3 verify
|
||||
1.4 target/target_index or setpolicy?
|
||||
1.5 target/target_index
|
||||
1.6 setpolicy
|
||||
1.7 get_intermediate and target_intermediate
|
||||
2. Frequency Table Helpers
|
||||
|
||||
|
||||
|
||||
@ -49,7 +41,7 @@ function check whether this kernel runs on the right CPU and the right
|
||||
chipset. If so, register a struct cpufreq_driver with the CPUfreq core
|
||||
using cpufreq_register_driver()
|
||||
|
||||
What shall this struct cpufreq_driver contain?
|
||||
What shall this struct cpufreq_driver contain?
|
||||
|
||||
.name - The name of this driver.
|
||||
|
||||
@ -108,37 +100,42 @@ Whenever a new CPU is registered with the device model, or after the
|
||||
cpufreq driver registers itself, the per-policy initialization function
|
||||
cpufreq_driver.init is called if no cpufreq policy existed for the CPU.
|
||||
Note that the .init() and .exit() routines are called only once for the
|
||||
policy and not for each CPU managed by the policy. It takes a struct
|
||||
cpufreq_policy *policy as argument. What to do now?
|
||||
policy and not for each CPU managed by the policy. It takes a ``struct
|
||||
cpufreq_policy *policy`` as argument. What to do now?
|
||||
|
||||
If necessary, activate the CPUfreq support on your CPU.
|
||||
|
||||
Then, the driver must fill in the following values:
|
||||
|
||||
policy->cpuinfo.min_freq _and_
|
||||
policy->cpuinfo.max_freq - the minimum and maximum frequency
|
||||
(in kHz) which is supported by
|
||||
this CPU
|
||||
policy->cpuinfo.transition_latency the time it takes on this CPU to
|
||||
switch between two frequencies in
|
||||
nanoseconds (if appropriate, else
|
||||
specify CPUFREQ_ETERNAL)
|
||||
|
||||
policy->cur The current operating frequency of
|
||||
this CPU (if appropriate)
|
||||
policy->min,
|
||||
policy->max,
|
||||
policy->policy and, if necessary,
|
||||
policy->governor must contain the "default policy" for
|
||||
this CPU. A few moments later,
|
||||
cpufreq_driver.verify and either
|
||||
cpufreq_driver.setpolicy or
|
||||
cpufreq_driver.target/target_index is called
|
||||
with these values.
|
||||
policy->cpus Update this with the masks of the
|
||||
(online + offline) CPUs that do DVFS
|
||||
along with this CPU (i.e. that share
|
||||
clock/voltage rails with it).
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|policy->cpuinfo.min_freq _and_ | |
|
||||
|policy->cpuinfo.max_freq | the minimum and maximum frequency |
|
||||
| | (in kHz) which is supported by |
|
||||
| | this CPU |
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|policy->cpuinfo.transition_latency | the time it takes on this CPU to |
|
||||
| | switch between two frequencies in |
|
||||
| | nanoseconds (if appropriate, else |
|
||||
| | specify CPUFREQ_ETERNAL) |
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|policy->cur | The current operating frequency of |
|
||||
| | this CPU (if appropriate) |
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|policy->min, | |
|
||||
|policy->max, | |
|
||||
|policy->policy and, if necessary, | |
|
||||
|policy->governor | must contain the "default policy" for|
|
||||
| | this CPU. A few moments later, |
|
||||
| | cpufreq_driver.verify and either |
|
||||
| | cpufreq_driver.setpolicy or |
|
||||
| | cpufreq_driver.target/target_index is|
|
||||
| | called with these values. |
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|policy->cpus | Update this with the masks of the |
|
||||
| | (online + offline) CPUs that do DVFS |
|
||||
| | along with this CPU (i.e. that share|
|
||||
| | clock/voltage rails with it). |
|
||||
+-----------------------------------+--------------------------------------+
|
||||
|
||||
For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the
|
||||
frequency table helpers might be helpful. See the section 2 for more information
|
||||
@ -151,8 +148,8 @@ on them.
|
||||
When the user decides a new policy (consisting of
|
||||
"policy,governor,min,max") shall be set, this policy must be validated
|
||||
so that incompatible values can be corrected. For verifying these
|
||||
values cpufreq_verify_within_limits(struct cpufreq_policy *policy,
|
||||
unsigned int min_freq, unsigned int max_freq) function might be helpful.
|
||||
values cpufreq_verify_within_limits(``struct cpufreq_policy *policy``,
|
||||
``unsigned int min_freq``, ``unsigned int max_freq``) function might be helpful.
|
||||
See section 2 for details on frequency table helpers.
|
||||
|
||||
You need to make sure that at least one valid frequency (or operating
|
||||
@ -163,7 +160,7 @@ policy->max first, and only if this is no solution, decrease policy->min.
|
||||
1.4 target or target_index or setpolicy or fast_switch?
|
||||
-------------------------------------------------------
|
||||
|
||||
Most cpufreq drivers or even most cpu frequency scaling algorithms
|
||||
Most cpufreq drivers or even most cpu frequency scaling algorithms
|
||||
only allow the CPU frequency to be set to predefined fixed values. For
|
||||
these, you use the ->target(), ->target_index() or ->fast_switch()
|
||||
callbacks.
|
||||
@ -175,8 +172,8 @@ limits on their own. These shall use the ->setpolicy() callback.
|
||||
1.5. target/target_index
|
||||
------------------------
|
||||
|
||||
The target_index call has two arguments: struct cpufreq_policy *policy,
|
||||
and unsigned int index (into the exposed frequency table).
|
||||
The target_index call has two arguments: ``struct cpufreq_policy *policy``,
|
||||
and ``unsigned int`` index (into the exposed frequency table).
|
||||
|
||||
The CPUfreq driver must set the new frequency when called here. The
|
||||
actual frequency must be determined by freq_table[index].frequency.
|
||||
@ -184,9 +181,9 @@ actual frequency must be determined by freq_table[index].frequency.
|
||||
It should always restore to earlier frequency (i.e. policy->restore_freq) in
|
||||
case of errors, even if we switched to intermediate frequency earlier.
|
||||
|
||||
Deprecated:
|
||||
Deprecated
|
||||
----------
|
||||
The target call has three arguments: struct cpufreq_policy *policy,
|
||||
The target call has three arguments: ``struct cpufreq_policy *policy``,
|
||||
unsigned int target_frequency, unsigned int relation.
|
||||
|
||||
The CPUfreq driver must set the new frequency when called here. The
|
||||
@ -210,14 +207,14 @@ Not all drivers are expected to implement it, as sleeping from within
|
||||
this callback isn't allowed. This callback must be highly optimized to
|
||||
do switching as fast as possible.
|
||||
|
||||
This function has two arguments: struct cpufreq_policy *policy and
|
||||
unsigned int target_frequency.
|
||||
This function has two arguments: ``struct cpufreq_policy *policy`` and
|
||||
``unsigned int target_frequency``.
|
||||
|
||||
|
||||
1.7 setpolicy
|
||||
-------------
|
||||
|
||||
The setpolicy call only takes a struct cpufreq_policy *policy as
|
||||
The setpolicy call only takes a ``struct cpufreq_policy *policy`` as
|
||||
argument. You need to set the lower limit of the in-processor or
|
||||
in-chipset dynamic frequency switching to policy->min, the upper limit
|
||||
to policy->max, and -if supported- select a performance-oriented
|
||||
@ -278,10 +275,10 @@ table.
|
||||
|
||||
cpufreq_for_each_valid_entry(pos, table) - iterates over all entries,
|
||||
excluding CPUFREQ_ENTRY_INVALID frequencies.
|
||||
Use arguments "pos" - a cpufreq_frequency_table * as a loop cursor and
|
||||
"table" - the cpufreq_frequency_table * you want to iterate over.
|
||||
Use arguments "pos" - a ``cpufreq_frequency_table *`` as a loop cursor and
|
||||
"table" - the ``cpufreq_frequency_table *`` you want to iterate over.
|
||||
|
||||
For example:
|
||||
For example::
|
||||
|
||||
struct cpufreq_frequency_table *pos, *driver_freq_table;
|
||||
|
||||
@ -1,19 +0,0 @@
|
||||
|
||||
The cpufreq-nforce2 driver changes the FSB on nVidia nForce2 platforms.
|
||||
|
||||
This works better than on other platforms, because the FSB of the CPU
|
||||
can be controlled independently from the PCI/AGP clock.
|
||||
|
||||
The module has two options:
|
||||
|
||||
fid: multiplier * 10 (for example 8.5 = 85)
|
||||
min_fsb: minimum FSB
|
||||
|
||||
If not set, fid is calculated from the current CPU speed and the FSB.
|
||||
min_fsb defaults to FSB at boot time - 50 MHz.
|
||||
|
||||
IMPORTANT: The available range is limited downwards!
|
||||
Also the minimum available FSB can differ, for systems
|
||||
booting with 200 MHz, 150 should always work.
|
||||
|
||||
|
||||
@ -1,21 +1,23 @@
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
CPU frequency and voltage scaling statistics in the Linux(TM) kernel
|
||||
==========================================
|
||||
General Description of sysfs CPUFreq Stats
|
||||
==========================================
|
||||
|
||||
information for users
|
||||
|
||||
|
||||
L i n u x c p u f r e q - s t a t s d r i v e r
|
||||
Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
|
||||
|
||||
- information for users -
|
||||
.. Contents
|
||||
|
||||
|
||||
Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
|
||||
|
||||
Contents
|
||||
1. Introduction
|
||||
2. Statistics Provided (with example)
|
||||
3. Configuring cpufreq-stats
|
||||
1. Introduction
|
||||
2. Statistics Provided (with example)
|
||||
3. Configuring cpufreq-stats
|
||||
|
||||
|
||||
1. Introduction
|
||||
===============
|
||||
|
||||
cpufreq-stats is a driver that provides CPU frequency statistics for each CPU.
|
||||
These statistics are provided in /sysfs as a bunch of read_only interfaces. This
|
||||
@ -28,8 +30,10 @@ that may be running on your CPU. So, it will work with any cpufreq_driver.
|
||||
|
||||
|
||||
2. Statistics Provided (with example)
|
||||
=====================================
|
||||
|
||||
cpufreq stats provides following statistics (explained in detail below).
|
||||
|
||||
- time_in_state
|
||||
- total_trans
|
||||
- trans_table
|
||||
@ -39,53 +43,57 @@ All the statistics will be from the time the stats driver has been inserted
|
||||
statistic is done. Obviously, stats driver will not have any information
|
||||
about the frequency transitions before the stats driver insertion.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l
|
||||
total 0
|
||||
drwxr-xr-x 2 root root 0 May 14 16:06 .
|
||||
drwxr-xr-x 3 root root 0 May 14 15:58 ..
|
||||
--w------- 1 root root 4096 May 14 16:06 reset
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 time_in_state
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 total_trans
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 trans_table
|
||||
--------------------------------------------------------------------------------
|
||||
::
|
||||
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l
|
||||
total 0
|
||||
drwxr-xr-x 2 root root 0 May 14 16:06 .
|
||||
drwxr-xr-x 3 root root 0 May 14 15:58 ..
|
||||
--w------- 1 root root 4096 May 14 16:06 reset
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 time_in_state
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 total_trans
|
||||
-r--r--r-- 1 root root 4096 May 14 16:06 trans_table
|
||||
|
||||
- **reset**
|
||||
|
||||
- reset
|
||||
Write-only attribute that can be used to reset the stat counters. This can be
|
||||
useful for evaluating system behaviour under different governors without the
|
||||
need for a reboot.
|
||||
|
||||
- time_in_state
|
||||
- **time_in_state**
|
||||
|
||||
This gives the amount of time spent in each of the frequencies supported by
|
||||
this CPU. The cat output will have "<frequency> <time>" pair in each line, which
|
||||
will mean this CPU spent <time> usertime units of time at <frequency>. Output
|
||||
will have one line for each of the supported frequencies. usertime units here
|
||||
will have one line for each of the supported frequencies. usertime units here
|
||||
is 10mS (similar to other time exported in /proc).
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state
|
||||
3600000 2089
|
||||
3400000 136
|
||||
3200000 34
|
||||
3000000 67
|
||||
2800000 172488
|
||||
--------------------------------------------------------------------------------
|
||||
::
|
||||
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state
|
||||
3600000 2089
|
||||
3400000 136
|
||||
3200000 34
|
||||
3000000 67
|
||||
2800000 172488
|
||||
|
||||
|
||||
- total_trans
|
||||
This gives the total number of frequency transitions on this CPU. The cat
|
||||
- **total_trans**
|
||||
|
||||
This gives the total number of frequency transitions on this CPU. The cat
|
||||
output will have a single count which is the total number of frequency
|
||||
transitions.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans
|
||||
20
|
||||
--------------------------------------------------------------------------------
|
||||
::
|
||||
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans
|
||||
20
|
||||
|
||||
- **trans_table**
|
||||
|
||||
- trans_table
|
||||
This will give a fine grained information about all the CPU frequency
|
||||
transitions. The cat output here is a two dimensional matrix, where an entry
|
||||
<i,j> (row i, column j) represents the count of number of transitions from
|
||||
<i,j> (row i, column j) represents the count of number of transitions from
|
||||
Freq_i to Freq_j. Freq_i rows and Freq_j columns follow the sorting order in
|
||||
which the driver has provided the frequency table initially to the cpufreq core
|
||||
and so can be sorted (ascending or descending) or unsorted. The output here
|
||||
@ -95,26 +103,27 @@ readability.
|
||||
If the transition table is bigger than PAGE_SIZE, reading this will
|
||||
return an -EFBIG error.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table
|
||||
From : To
|
||||
: 3600000 3400000 3200000 3000000 2800000
|
||||
3600000: 0 5 0 0 0
|
||||
3400000: 4 0 2 0 0
|
||||
3200000: 0 1 0 2 0
|
||||
3000000: 0 0 1 0 3
|
||||
2800000: 0 0 0 2 0
|
||||
--------------------------------------------------------------------------------
|
||||
::
|
||||
|
||||
<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table
|
||||
From : To
|
||||
: 3600000 3400000 3200000 3000000 2800000
|
||||
3600000: 0 5 0 0 0
|
||||
3400000: 4 0 2 0 0
|
||||
3200000: 0 1 0 2 0
|
||||
3000000: 0 0 1 0 3
|
||||
2800000: 0 0 0 2 0
|
||||
|
||||
3. Configuring cpufreq-stats
|
||||
============================
|
||||
|
||||
To configure cpufreq-stats in your kernel
|
||||
Config Main Menu
|
||||
Power management options (ACPI, APM) --->
|
||||
CPU Frequency scaling --->
|
||||
[*] CPU Frequency scaling
|
||||
[*] CPU frequency translation statistics
|
||||
To configure cpufreq-stats in your kernel::
|
||||
|
||||
Config Main Menu
|
||||
Power management options (ACPI, APM) --->
|
||||
CPU Frequency scaling --->
|
||||
[*] CPU Frequency scaling
|
||||
[*] CPU frequency translation statistics
|
||||
|
||||
|
||||
"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure
|
||||
39
Documentation/cpu-freq/index.rst
Normal file
39
Documentation/cpu-freq/index.rst
Normal file
@ -0,0 +1,39 @@
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
==============================================================================
|
||||
Linux CPUFreq - CPU frequency and voltage scaling code in the Linux(TM) kernel
|
||||
==============================================================================
|
||||
|
||||
Author: Dominik Brodowski <linux@brodo.de>
|
||||
|
||||
Clock scaling allows you to change the clock speed of the CPUs on the
|
||||
fly. This is a nice method to save battery power, because the lower
|
||||
the clock speed, the less power the CPU consumes.
|
||||
|
||||
|
||||
.. toctree::
|
||||
:maxdepth: 1
|
||||
|
||||
core
|
||||
cpu-drivers
|
||||
cpufreq-stats
|
||||
|
||||
Mailing List
|
||||
------------
|
||||
There is a CPU frequency changing CVS commit and general list where
|
||||
you can report bugs, problems or submit patches. To post a message,
|
||||
send an email to linux-pm@vger.kernel.org.
|
||||
|
||||
Links
|
||||
-----
|
||||
the FTP archives:
|
||||
* ftp://ftp.linux.org.uk/pub/linux/cpufreq/
|
||||
|
||||
how to access the CVS repository:
|
||||
* http://cvs.arm.linux.org.uk/
|
||||
|
||||
the CPUFreq Mailing list:
|
||||
* http://vger.kernel.org/vger-lists.html#linux-pm
|
||||
|
||||
Clock and voltage scaling for the SA-1100:
|
||||
* http://www.lartmaker.nl/projects/scaling
|
||||
@ -1,56 +0,0 @@
|
||||
CPU frequency and voltage scaling code in the Linux(TM) kernel
|
||||
|
||||
|
||||
L i n u x C P U F r e q
|
||||
|
||||
|
||||
|
||||
|
||||
Dominik Brodowski <linux@brodo.de>
|
||||
|
||||
|
||||
|
||||
Clock scaling allows you to change the clock speed of the CPUs on the
|
||||
fly. This is a nice method to save battery power, because the lower
|
||||
the clock speed, the less power the CPU consumes.
|
||||
|
||||
|
||||
|
||||
Documents in this directory:
|
||||
----------------------------
|
||||
|
||||
amd-powernow.txt - AMD powernow driver specific file.
|
||||
|
||||
core.txt - General description of the CPUFreq core and
|
||||
of CPUFreq notifiers.
|
||||
|
||||
cpu-drivers.txt - How to implement a new cpufreq processor driver.
|
||||
|
||||
cpufreq-nforce2.txt - nVidia nForce2 platform specific file.
|
||||
|
||||
cpufreq-stats.txt - General description of sysfs cpufreq stats.
|
||||
|
||||
index.txt - File index, Mailing list and Links (this document)
|
||||
|
||||
pcc-cpufreq.txt - PCC cpufreq driver specific file.
|
||||
|
||||
|
||||
Mailing List
|
||||
------------
|
||||
There is a CPU frequency changing CVS commit and general list where
|
||||
you can report bugs, problems or submit patches. To post a message,
|
||||
send an email to linux-pm@vger.kernel.org.
|
||||
|
||||
Links
|
||||
-----
|
||||
the FTP archives:
|
||||
* ftp://ftp.linux.org.uk/pub/linux/cpufreq/
|
||||
|
||||
how to access the CVS repository:
|
||||
* http://cvs.arm.linux.org.uk/
|
||||
|
||||
the CPUFreq Mailing list:
|
||||
* http://vger.kernel.org/vger-lists.html#linux-pm
|
||||
|
||||
Clock and voltage scaling for the SA-1100:
|
||||
* http://www.lartmaker.nl/projects/scaling
|
||||
@ -1,207 +0,0 @@
|
||||
/*
|
||||
* pcc-cpufreq.txt - PCC interface documentation
|
||||
*
|
||||
* Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
|
||||
* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
|
||||
* Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
|
||||
*
|
||||
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
* the Free Software Foundation; version 2 of the License.
|
||||
*
|
||||
* This program is distributed in the hope that it will be useful, but
|
||||
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON
|
||||
* INFRINGEMENT. See the GNU General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License along
|
||||
* with this program; if not, write to the Free Software Foundation, Inc.,
|
||||
* 675 Mass Ave, Cambridge, MA 02139, USA.
|
||||
*
|
||||
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
*/
|
||||
|
||||
|
||||
Processor Clocking Control Driver
|
||||
---------------------------------
|
||||
|
||||
Contents:
|
||||
---------
|
||||
1. Introduction
|
||||
1.1 PCC interface
|
||||
1.1.1 Get Average Frequency
|
||||
1.1.2 Set Desired Frequency
|
||||
1.2 Platforms affected
|
||||
2. Driver and /sys details
|
||||
2.1 scaling_available_frequencies
|
||||
2.2 cpuinfo_transition_latency
|
||||
2.3 cpuinfo_cur_freq
|
||||
2.4 related_cpus
|
||||
3. Caveats
|
||||
|
||||
1. Introduction:
|
||||
----------------
|
||||
Processor Clocking Control (PCC) is an interface between the platform
|
||||
firmware and OSPM. It is a mechanism for coordinating processor
|
||||
performance (ie: frequency) between the platform firmware and the OS.
|
||||
|
||||
The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC
|
||||
interface.
|
||||
|
||||
OS utilizes the PCC interface to inform platform firmware what frequency the
|
||||
OS wants for a logical processor. The platform firmware attempts to achieve
|
||||
the requested frequency. If the request for the target frequency could not be
|
||||
satisfied by platform firmware, then it usually means that power budget
|
||||
conditions are in place, and "power capping" is taking place.
|
||||
|
||||
1.1 PCC interface:
|
||||
------------------
|
||||
The complete PCC specification is available here:
|
||||
http://www.acpica.org/download/Processor-Clocking-Control-v1p0.pdf
|
||||
|
||||
PCC relies on a shared memory region that provides a channel for communication
|
||||
between the OS and platform firmware. PCC also implements a "doorbell" that
|
||||
is used by the OS to inform the platform firmware that a command has been
|
||||
sent.
|
||||
|
||||
The ACPI PCCH() method is used to discover the location of the PCC shared
|
||||
memory region. The shared memory region header contains the "command" and
|
||||
"status" interface. PCCH() also contains details on how to access the platform
|
||||
doorbell.
|
||||
|
||||
The following commands are supported by the PCC interface:
|
||||
* Get Average Frequency
|
||||
* Set Desired Frequency
|
||||
|
||||
The ACPI PCCP() method is implemented for each logical processor and is
|
||||
used to discover the offsets for the input and output buffers in the shared
|
||||
memory region.
|
||||
|
||||
When PCC mode is enabled, the platform will not expose processor performance
|
||||
or throttle states (_PSS, _TSS and related ACPI objects) to OSPM. Therefore,
|
||||
the native P-state driver (such as acpi-cpufreq for Intel, powernow-k8 for
|
||||
AMD) will not load.
|
||||
|
||||
However, OSPM remains in control of policy. The governor (eg: "ondemand")
|
||||
computes the required performance for each processor based on server workload.
|
||||
The PCC driver fills in the command interface, and the input buffer and
|
||||
communicates the request to the platform firmware. The platform firmware is
|
||||
responsible for delivering the requested performance.
|
||||
|
||||
Each PCC command is "global" in scope and can affect all the logical CPUs in
|
||||
the system. Therefore, PCC is capable of performing "group" updates. With PCC
|
||||
the OS is capable of getting/setting the frequency of all the logical CPUs in
|
||||
the system with a single call to the BIOS.
|
||||
|
||||
1.1.1 Get Average Frequency:
|
||||
----------------------------
|
||||
This command is used by the OSPM to query the running frequency of the
|
||||
processor since the last time this command was completed. The output buffer
|
||||
indicates the average unhalted frequency of the logical processor expressed as
|
||||
a percentage of the nominal (ie: maximum) CPU frequency. The output buffer
|
||||
also signifies if the CPU frequency is limited by a power budget condition.
|
||||
|
||||
1.1.2 Set Desired Frequency:
|
||||
----------------------------
|
||||
This command is used by the OSPM to communicate to the platform firmware the
|
||||
desired frequency for a logical processor. The output buffer is currently
|
||||
ignored by OSPM. The next invocation of "Get Average Frequency" will inform
|
||||
OSPM if the desired frequency was achieved or not.
|
||||
|
||||
1.2 Platforms affected:
|
||||
-----------------------
|
||||
The PCC driver will load on any system where the platform firmware:
|
||||
* supports the PCC interface, and the associated PCCH() and PCCP() methods
|
||||
* assumes responsibility for managing the hardware clocking controls in order
|
||||
to deliver the requested processor performance
|
||||
|
||||
Currently, certain HP ProLiant platforms implement the PCC interface. On those
|
||||
platforms PCC is the "default" choice.
|
||||
|
||||
However, it is possible to disable this interface via a BIOS setting. In
|
||||
such an instance, as is also the case on platforms where the PCC interface
|
||||
is not implemented, the PCC driver will fail to load silently.
|
||||
|
||||
2. Driver and /sys details:
|
||||
---------------------------
|
||||
When the driver loads, it merely prints the lowest and the highest CPU
|
||||
frequencies supported by the platform firmware.
|
||||
|
||||
The PCC driver loads with a message such as:
|
||||
pcc-cpufreq: (v1.00.00) driver loaded with frequency limits: 1600 MHz, 2933
|
||||
MHz
|
||||
|
||||
This means that the OPSM can request the CPU to run at any frequency in
|
||||
between the limits (1600 MHz, and 2933 MHz) specified in the message.
|
||||
|
||||
Internally, there is no need for the driver to convert the "target" frequency
|
||||
to a corresponding P-state.
|
||||
|
||||
The VERSION number for the driver will be of the format v.xy.ab.
|
||||
eg: 1.00.02
|
||||
----- --
|
||||
| |
|
||||
| -- this will increase with bug fixes/enhancements to the driver
|
||||
|-- this is the version of the PCC specification the driver adheres to
|
||||
|
||||
|
||||
The following is a brief discussion on some of the fields exported via the
|
||||
/sys filesystem and how their values are affected by the PCC driver:
|
||||
|
||||
2.1 scaling_available_frequencies:
|
||||
----------------------------------
|
||||
scaling_available_frequencies is not created in /sys. No intermediate
|
||||
frequencies need to be listed because the BIOS will try to achieve any
|
||||
frequency, within limits, requested by the governor. A frequency does not have
|
||||
to be strictly associated with a P-state.
|
||||
|
||||
2.2 cpuinfo_transition_latency:
|
||||
-------------------------------
|
||||
The cpuinfo_transition_latency field is 0. The PCC specification does
|
||||
not include a field to expose this value currently.
|
||||
|
||||
2.3 cpuinfo_cur_freq:
|
||||
---------------------
|
||||
A) Often cpuinfo_cur_freq will show a value different than what is declared
|
||||
in the scaling_available_frequencies or scaling_cur_freq, or scaling_max_freq.
|
||||
This is due to "turbo boost" available on recent Intel processors. If certain
|
||||
conditions are met the BIOS can achieve a slightly higher speed than requested
|
||||
by OSPM. An example:
|
||||
|
||||
scaling_cur_freq : 2933000
|
||||
cpuinfo_cur_freq : 3196000
|
||||
|
||||
B) There is a round-off error associated with the cpuinfo_cur_freq value.
|
||||
Since the driver obtains the current frequency as a "percentage" (%) of the
|
||||
nominal frequency from the BIOS, sometimes, the values displayed by
|
||||
scaling_cur_freq and cpuinfo_cur_freq may not match. An example:
|
||||
|
||||
scaling_cur_freq : 1600000
|
||||
cpuinfo_cur_freq : 1583000
|
||||
|
||||
In this example, the nominal frequency is 2933 MHz. The driver obtains the
|
||||
current frequency, cpuinfo_cur_freq, as 54% of the nominal frequency:
|
||||
|
||||
54% of 2933 MHz = 1583 MHz
|
||||
|
||||
Nominal frequency is the maximum frequency of the processor, and it usually
|
||||
corresponds to the frequency of the P0 P-state.
|
||||
|
||||
2.4 related_cpus:
|
||||
-----------------
|
||||
The related_cpus field is identical to affected_cpus.
|
||||
|
||||
affected_cpus : 4
|
||||
related_cpus : 4
|
||||
|
||||
Currently, the PCC driver does not evaluate _PSD. The platforms that support
|
||||
PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination
|
||||
to ensure that the same frequency is requested of all dependent CPUs.
|
||||
|
||||
3. Caveats:
|
||||
-----------
|
||||
The "cpufreq_stats" module in its present form cannot be loaded and
|
||||
expected to work with the PCC driver. Since the "cpufreq_stats" module
|
||||
provides information wrt each P-state, it is not applicable to the PCC driver.
|
||||
@ -99,6 +99,7 @@ needed).
|
||||
accounting/index
|
||||
block/index
|
||||
cdrom/index
|
||||
cpu-freq/index
|
||||
ide/index
|
||||
fb/index
|
||||
fpga/index
|
||||
|
||||
@ -25,7 +25,7 @@ config X86_PCC_CPUFREQ
|
||||
This driver adds support for the PCC interface.
|
||||
|
||||
For details, take a look at:
|
||||
<file:Documentation/cpu-freq/pcc-cpufreq.txt>.
|
||||
<file:Documentation/admin-guide/pm/cpufreq_drivers.rst>.
|
||||
|
||||
To compile this driver as a module, choose M here: the
|
||||
module will be called pcc-cpufreq.
|
||||
|
||||
@ -550,14 +550,14 @@ out:
|
||||
EXPORT_SYMBOL(devfreq_monitor_resume);
|
||||
|
||||
/**
|
||||
* devfreq_interval_update() - Update device devfreq monitoring interval
|
||||
* devfreq_update_interval() - Update device devfreq monitoring interval
|
||||
* @devfreq: the devfreq instance.
|
||||
* @delay: new polling interval to be set.
|
||||
*
|
||||
* Helper function to set new load monitoring polling interval. Function
|
||||
* to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
|
||||
* to be called from governor in response to DEVFREQ_GOV_UPDATE_INTERVAL event.
|
||||
*/
|
||||
void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
|
||||
void devfreq_update_interval(struct devfreq *devfreq, unsigned int *delay)
|
||||
{
|
||||
unsigned int cur_delay = devfreq->profile->polling_ms;
|
||||
unsigned int new_delay = *delay;
|
||||
@ -597,7 +597,7 @@ void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
|
||||
out:
|
||||
mutex_unlock(&devfreq->lock);
|
||||
}
|
||||
EXPORT_SYMBOL(devfreq_interval_update);
|
||||
EXPORT_SYMBOL(devfreq_update_interval);
|
||||
|
||||
/**
|
||||
* devfreq_notifier_call() - Notify that the device frequency requirements
|
||||
@ -705,13 +705,13 @@ static void devfreq_dev_release(struct device *dev)
|
||||
|
||||
if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
|
||||
err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
|
||||
if (err)
|
||||
if (err < 0)
|
||||
dev_warn(dev->parent,
|
||||
"Failed to remove max_freq request: %d\n", err);
|
||||
}
|
||||
if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
|
||||
err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
|
||||
if (err)
|
||||
if (err < 0)
|
||||
dev_warn(dev->parent,
|
||||
"Failed to remove min_freq request: %d\n", err);
|
||||
}
|
||||
@ -1424,7 +1424,7 @@ static ssize_t polling_interval_store(struct device *dev,
|
||||
if (ret != 1)
|
||||
return -EINVAL;
|
||||
|
||||
df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
|
||||
df->governor->event_handler(df, DEVFREQ_GOV_UPDATE_INTERVAL, &value);
|
||||
ret = count;
|
||||
|
||||
return ret;
|
||||
|
||||
@ -18,7 +18,7 @@
|
||||
/* Devfreq events */
|
||||
#define DEVFREQ_GOV_START 0x1
|
||||
#define DEVFREQ_GOV_STOP 0x2
|
||||
#define DEVFREQ_GOV_INTERVAL 0x3
|
||||
#define DEVFREQ_GOV_UPDATE_INTERVAL 0x3
|
||||
#define DEVFREQ_GOV_SUSPEND 0x4
|
||||
#define DEVFREQ_GOV_RESUME 0x5
|
||||
|
||||
@ -30,7 +30,7 @@
|
||||
* @node: list node - contains registered devfreq governors
|
||||
* @name: Governor's name
|
||||
* @immutable: Immutable flag for governor. If the value is 1,
|
||||
* this govenror is never changeable to other governor.
|
||||
* this governor is never changeable to other governor.
|
||||
* @interrupt_driven: Devfreq core won't schedule polling work for this
|
||||
* governor if value is set to 1.
|
||||
* @get_target_freq: Returns desired operating frequency for the device.
|
||||
@ -57,17 +57,16 @@ struct devfreq_governor {
|
||||
unsigned int event, void *data);
|
||||
};
|
||||
|
||||
extern void devfreq_monitor_start(struct devfreq *devfreq);
|
||||
extern void devfreq_monitor_stop(struct devfreq *devfreq);
|
||||
extern void devfreq_monitor_suspend(struct devfreq *devfreq);
|
||||
extern void devfreq_monitor_resume(struct devfreq *devfreq);
|
||||
extern void devfreq_interval_update(struct devfreq *devfreq,
|
||||
unsigned int *delay);
|
||||
void devfreq_monitor_start(struct devfreq *devfreq);
|
||||
void devfreq_monitor_stop(struct devfreq *devfreq);
|
||||
void devfreq_monitor_suspend(struct devfreq *devfreq);
|
||||
void devfreq_monitor_resume(struct devfreq *devfreq);
|
||||
void devfreq_update_interval(struct devfreq *devfreq, unsigned int *delay);
|
||||
|
||||
extern int devfreq_add_governor(struct devfreq_governor *governor);
|
||||
extern int devfreq_remove_governor(struct devfreq_governor *governor);
|
||||
int devfreq_add_governor(struct devfreq_governor *governor);
|
||||
int devfreq_remove_governor(struct devfreq_governor *governor);
|
||||
|
||||
extern int devfreq_update_status(struct devfreq *devfreq, unsigned long freq);
|
||||
int devfreq_update_status(struct devfreq *devfreq, unsigned long freq);
|
||||
|
||||
static inline int devfreq_update_stats(struct devfreq *df)
|
||||
{
|
||||
|
||||
@ -96,8 +96,8 @@ static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
|
||||
devfreq_monitor_stop(devfreq);
|
||||
break;
|
||||
|
||||
case DEVFREQ_GOV_INTERVAL:
|
||||
devfreq_interval_update(devfreq, (unsigned int *)data);
|
||||
case DEVFREQ_GOV_UPDATE_INTERVAL:
|
||||
devfreq_update_interval(devfreq, (unsigned int *)data);
|
||||
break;
|
||||
|
||||
case DEVFREQ_GOV_SUSPEND:
|
||||
|
||||
@ -131,7 +131,7 @@ static int devfreq_userspace_handler(struct devfreq *devfreq,
|
||||
}
|
||||
|
||||
static struct devfreq_governor devfreq_userspace = {
|
||||
.name = "userspace",
|
||||
.name = DEVFREQ_GOV_USERSPACE,
|
||||
.get_target_freq = devfreq_userspace_func,
|
||||
.event_handler = devfreq_userspace_handler,
|
||||
};
|
||||
|
||||
@ -734,7 +734,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
|
||||
devfreq_monitor_stop(devfreq);
|
||||
break;
|
||||
|
||||
case DEVFREQ_GOV_INTERVAL:
|
||||
case DEVFREQ_GOV_UPDATE_INTERVAL:
|
||||
/*
|
||||
* ACTMON hardware supports up to 256 milliseconds for the
|
||||
* sampling period.
|
||||
@ -745,7 +745,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
|
||||
}
|
||||
|
||||
tegra_actmon_pause(tegra);
|
||||
devfreq_interval_update(devfreq, new_delay);
|
||||
devfreq_update_interval(devfreq, new_delay);
|
||||
ret = tegra_actmon_resume(tegra);
|
||||
break;
|
||||
|
||||
|
||||
@ -67,7 +67,7 @@ struct idle_inject_device {
|
||||
struct hrtimer timer;
|
||||
unsigned int idle_duration_us;
|
||||
unsigned int run_duration_us;
|
||||
unsigned long int cpumask[0];
|
||||
unsigned long cpumask[];
|
||||
};
|
||||
|
||||
static DEFINE_PER_CPU(struct idle_inject_thread, idle_inject_thread);
|
||||
|
||||
@ -158,7 +158,7 @@ struct devfreq_stats {
|
||||
* functions except for the context of callbacks defined in struct
|
||||
* devfreq_governor, the governor should protect its access with the
|
||||
* struct mutex lock in struct devfreq. A governor may use this mutex
|
||||
* to protect its own private data in void *data as well.
|
||||
* to protect its own private data in ``void *data`` as well.
|
||||
*/
|
||||
struct devfreq {
|
||||
struct list_head node;
|
||||
@ -201,24 +201,23 @@ struct devfreq_freqs {
|
||||
};
|
||||
|
||||
#if defined(CONFIG_PM_DEVFREQ)
|
||||
extern struct devfreq *devfreq_add_device(struct device *dev,
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data);
|
||||
extern int devfreq_remove_device(struct devfreq *devfreq);
|
||||
extern struct devfreq *devm_devfreq_add_device(struct device *dev,
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data);
|
||||
extern void devm_devfreq_remove_device(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
struct devfreq *devfreq_add_device(struct device *dev,
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data);
|
||||
int devfreq_remove_device(struct devfreq *devfreq);
|
||||
struct devfreq *devm_devfreq_add_device(struct device *dev,
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data);
|
||||
void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq);
|
||||
|
||||
/* Supposed to be called by PM callbacks */
|
||||
extern int devfreq_suspend_device(struct devfreq *devfreq);
|
||||
extern int devfreq_resume_device(struct devfreq *devfreq);
|
||||
int devfreq_suspend_device(struct devfreq *devfreq);
|
||||
int devfreq_resume_device(struct devfreq *devfreq);
|
||||
|
||||
extern void devfreq_suspend(void);
|
||||
extern void devfreq_resume(void);
|
||||
void devfreq_suspend(void);
|
||||
void devfreq_resume(void);
|
||||
|
||||
/**
|
||||
* update_devfreq() - Reevaluate the device and configure frequency
|
||||
@ -226,39 +225,38 @@ extern void devfreq_resume(void);
|
||||
*
|
||||
* Note: devfreq->lock must be held
|
||||
*/
|
||||
extern int update_devfreq(struct devfreq *devfreq);
|
||||
int update_devfreq(struct devfreq *devfreq);
|
||||
|
||||
/* Helper functions for devfreq user device driver with OPP. */
|
||||
extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
|
||||
unsigned long *freq, u32 flags);
|
||||
extern int devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
extern int devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
extern int devm_devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
extern int devfreq_register_notifier(struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
extern int devfreq_unregister_notifier(struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
extern int devm_devfreq_register_notifier(struct device *dev,
|
||||
struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
|
||||
unsigned long *freq, u32 flags);
|
||||
int devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
int devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
int devm_devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
void devm_devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq);
|
||||
int devfreq_register_notifier(struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
int devfreq_unregister_notifier(struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
int devm_devfreq_register_notifier(struct device *dev,
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
extern void devm_devfreq_unregister_notifier(struct device *dev,
|
||||
void devm_devfreq_unregister_notifier(struct device *dev,
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list);
|
||||
extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
|
||||
int index);
|
||||
struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index);
|
||||
|
||||
#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
|
||||
/**
|
||||
* struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
|
||||
* struct devfreq_simple_ondemand_data - ``void *data`` fed to struct devfreq
|
||||
* and devfreq_add_device
|
||||
* @upthreshold: If the load is over this value, the frequency jumps.
|
||||
* Specify 0 to use the default. Valid value = 0 to 100.
|
||||
@ -278,7 +276,7 @@ struct devfreq_simple_ondemand_data {
|
||||
|
||||
#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
|
||||
/**
|
||||
* struct devfreq_passive_data - void *data fed to struct devfreq
|
||||
* struct devfreq_passive_data - ``void *data`` fed to struct devfreq
|
||||
* and devfreq_add_device
|
||||
* @parent: the devfreq instance of parent device.
|
||||
* @get_target_freq: Optional callback, Returns desired operating frequency
|
||||
@ -311,9 +309,9 @@ struct devfreq_passive_data {
|
||||
|
||||
#else /* !CONFIG_PM_DEVFREQ */
|
||||
static inline struct devfreq *devfreq_add_device(struct device *dev,
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data)
|
||||
struct devfreq_dev_profile *profile,
|
||||
const char *governor_name,
|
||||
void *data)
|
||||
{
|
||||
return ERR_PTR(-ENOSYS);
|
||||
}
|
||||
@ -350,31 +348,31 @@ static inline void devfreq_suspend(void) {}
|
||||
static inline void devfreq_resume(void) {}
|
||||
|
||||
static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
|
||||
unsigned long *freq, u32 flags)
|
||||
unsigned long *freq, u32 flags)
|
||||
{
|
||||
return ERR_PTR(-EINVAL);
|
||||
}
|
||||
|
||||
static inline int devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq)
|
||||
struct devfreq *devfreq)
|
||||
{
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static inline int devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq)
|
||||
struct devfreq *devfreq)
|
||||
{
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static inline int devm_devfreq_register_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq)
|
||||
struct devfreq *devfreq)
|
||||
{
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
|
||||
struct devfreq *devfreq)
|
||||
struct devfreq *devfreq)
|
||||
{
|
||||
}
|
||||
|
||||
@ -393,22 +391,22 @@ static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
|
||||
}
|
||||
|
||||
static inline int devm_devfreq_register_notifier(struct device *dev,
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list)
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
|
||||
static inline void devm_devfreq_unregister_notifier(struct device *dev,
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list)
|
||||
struct devfreq *devfreq,
|
||||
struct notifier_block *nb,
|
||||
unsigned int list)
|
||||
{
|
||||
}
|
||||
|
||||
static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
|
||||
int index)
|
||||
int index)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user