58fe9c4621
1445 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Davidlohr Bueso
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58fe9c4621 |
sched/core: Fix comment typo in wake_q_add()
... the comment clearly refers to wake_up_q(), and not wake_up_list(). Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dave@stgolabs.net Link: http://lkml.kernel.org/r/1462766290-28664-1-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Muhammad Falak R Wani
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8c5e95548d |
sched/core: Remove unused variable
Remove unused variable 'ret', and directly return 0. Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1462441879-10092-1-git-send-email-falakreyaz@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dietmar Eggemann
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885e542ce8 |
sched/fair: Fix comment in calculate_imbalance()
The comment in calculate_imbalance() was introduced in commit: |
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Dietmar Eggemann
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0a9b23ce46 |
sched/fair: Remove stale power aware scheduling comments
Commit
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Matt Fleming
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b52fad2db5 |
sched/fair: Update rq clock before updating nohz CPU load
If we're accessing rq_clock() (e.g. in sched_avg_update()) we should update the rq clock before calling cpu_load_update(), otherwise any time calculations will be stale. All other paths currently call update_rq_clock(). Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1462304814-11715-1-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Wanpeng Li
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db6ea2fb09 |
sched/debug: Print out idle balance values even on !CONFIG_SCHEDSTATS kernels
The max_idle_balance_cost and avg_idle values which are tracked and ar used to capture short idle incidents, are not associated with schedstats, however the information of these two values isn't printed out on !CONFIG_SCHEDSTATS kernels. Fix this by moving the value printout out of the CONFIG_SCHEDSTATS section. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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> Link: http://lkml.kernel.org/r/1462250305-4523-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Yuyang Du
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7b20b916e9 |
sched/fair: Optimize sum computation with a lookup table
__compute_runnable_contrib() uses a loop to compute sum, whereas a table lookup can do it faster in a constant amount of time. The program to generate the constants is located at: Documentation/scheduler/sched-avg.txt Signed-off-by: Yuyang Du <yuyang.du@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Morten Rasmussen <morten.rasmussen@arm.com> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> 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: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: juri.lelli@arm.com Cc: pjt@google.com Link: http://lkml.kernel.org/r/1462226078-31904-2-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Yuyang Du
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172895e6b5 |
sched/fair: Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT and remove SCHED_LOAD_SCALE
After cleaning up the sched metrics, there are two definitions that are ambiguous and confusing: SCHED_LOAD_SHIFT and SCHED_LOAD_SHIFT. Resolve this: - Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT, which better reflects what it is. - Replace SCHED_LOAD_SCALE use with SCHED_CAPACITY_SCALE and remove SCHED_LOAD_SCALE. Suggested-by: Ben Segall <bsegall@google.com> Signed-off-by: Yuyang Du <yuyang.du@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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: dietmar.eggemann@arm.com Cc: lizefan@huawei.com Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: umgwanakikbuti@gmail.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1459829551-21625-3-git-send-email-yuyang.du@intel.com [ Rewrote the changelog and fixed the build on 32-bit kernels. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Yuyang Du
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6ecdd74962 |
sched/fair: Generalize the load/util averages resolution definition
Integer metric needs fixed point arithmetic. In sched/fair, a few metrics, e.g., weight, load, load_avg, util_avg, freq, and capacity, may have different fixed point ranges, which makes their update and usage error-prone. In order to avoid the errors relating to the fixed point range, we definie a basic fixed point range, and then formalize all metrics to base on the basic range. The basic range is 1024 or (1 << 10). Further, one can recursively apply the basic range to have larger range. Pointed out by Ben Segall, weight (visible to user, e.g., NICE-0 has 1024) and load (e.g., NICE_0_LOAD) have independent ranges, but they must be well calibrated. Signed-off-by: Yuyang Du <yuyang.du@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: lizefan@huawei.com Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: umgwanakikbuti@gmail.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1459829551-21625-2-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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2159197d66 |
sched/core: Enable increased load resolution on 64-bit kernels
Mike ran into the low load resolution limitation on his big machine. So reenable these bits; nobody could ever reproduce/analyze the reported power usage claim and Google has been running with this for years as well. Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com> Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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> |
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Peter Zijlstra
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e7904a28f5 |
locking/lockdep, sched/core: Implement a better lock pinning scheme
The problem with the existing lock pinning is that each pin is of value 1; this mean you can simply unpin if you know its pinned, without having any extra information. This scheme generates a random (16 bit) cookie for each pin and requires this same cookie to unpin. This means you have to keep the cookie in context. No objsize difference for !LOCKDEP kernels. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 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> |
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Peter Zijlstra
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eb58075149 |
sched/core: Introduce 'struct rq_flags'
In order to be able to pass around more than just the IRQ flags in the future, add a rq_flags structure. No difference in code generation for the x86_64-defconfig build I tested. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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> Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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3e71a462dd |
sched/core: Move task_rq_lock() out of line
Its a rather large function, inline doesn't seems to make much sense:
$ size defconfig-build/kernel/sched/core.o{.orig,}
text data bss dec hex filename
56533 21037 2320 79890 13812 defconfig-build/kernel/sched/core.o.orig
55733 21037 2320 79090 134f2 defconfig-build/kernel/sched/core.o
The 'perf bench sched messaging' micro-benchmark shows a visible improvement
of 4-5%:
$ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i ; done
$ perf stat --null --repeat 25 -- perf bench sched messaging -g 40 -l 5000
pre:
4.582798193 seconds time elapsed ( +- 1.41% )
4.733374877 seconds time elapsed ( +- 2.10% )
4.560955136 seconds time elapsed ( +- 1.43% )
4.631062303 seconds time elapsed ( +- 1.40% )
post:
4.364765213 seconds time elapsed ( +- 0.91% )
4.454442734 seconds time elapsed ( +- 1.18% )
4.448893817 seconds time elapsed ( +- 1.41% )
4.424346872 seconds time elapsed ( +- 0.97% )
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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>
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Ingo Molnar
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64b7aad579 |
Merge branch 'sched/urgent' into sched/core, to pick up fixes before applying new changes
Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Andy Lutomirski
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f98db6013c |
sched/core: Add switch_mm_irqs_off() and use it in the scheduler
By default, this is the same thing as switch_mm(). x86 will override it as an optimization. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/df401df47bdd6be3e389c6f1e3f5310d70e81b2c.1461688545.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Wanpeng Li
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594dd290cf |
sched/cpufreq: Optimize cpufreq update kicker to avoid update multiple times
Sometimes delta_exec is 0 due to update_curr() is called multiple times, this is captured by: u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start; This patch optimizes the cpufreq update kicker by bailing out when nothing changed, it will benefit the upcoming schedutil, since otherwise it will (over)react to the special util/max combination. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1461316044-9520-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Peter Zijlstra
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2548d546d4 |
nohz/full, sched/rt: Fix missed tick-reenabling bug in sched_can_stop_tick()
Chris Metcalf reported a that sched_can_stop_tick() sometimes fails to
re-enable the tick.
His observed problem is that rq->cfs.nr_running can be 1 even though
there are multiple runnable CFS tasks. This happens in the cgroup
case, in which case cfs.nr_running is the number of runnable entities
for that level.
If there is a single runnable cgroup (which can have an arbitrary
number of runnable child entries itself) rq->cfs.nr_running will be 1.
However, looking at that function I think there's more problems with it.
It seems to assume that if there's FIFO tasks, those will run. This is
incorrect. The FIFO task can have a lower prio than an RR task, in which
case the RR task will run.
So the whole fifo_nr_running test seems misplaced, it should go after
the rr_nr_running tests. That is, only if !rr_nr_running, can we use
fifo_nr_running like this.
Reported-by: Chris Metcalf <cmetcalf@mellanox.com>
Tested-by: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Fixes:
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Xunlei Pang
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fec148c000 |
sched/deadline: Fix a bug in dl_overflow()
I got a minus(very big) dl_b->total_bw during my deadline tests.
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -222297900
Something unusual must have happened.
After some digging, I finally noticed that when changing a deadline
task to normal(cfs), and changing it back to deadline immediately,
after it died, we will got the wrong dl_bw->total_bw.
The root cause is in dl_overflow(), it has:
if (new_bw == p->dl.dl_bw)
return 0;
1) When a deadline task is changed to !deadline task, it will start
dl timer in switched_from_dl(), and retain previous deadline parameter
till the timer expires.
2) If we change it back to deadline with the same bandwidth parameter
before the timer expires, as it keeps the old bandwidth although it
is not a deadline task. dl_overflow() simply returns success without
updating the right data, and got the wrong dl_bw->total_bw.
The solution is simple, if @p is not deadline, don't return.
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1460636368-1993-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Frederic Weisbecker
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9fd81dd5ce |
sched/fair: Optimize !CONFIG_NO_HZ_COMMON CPU load updates
Some code in CPU load update only concern NO_HZ configs but it is built on all configurations. When NO_HZ isn't built, that code is harmless but just happens to take some useless ressources in CPU and memory: 1) one useless field in struct rq 2) jiffies record on every tick that is never used (cpu_load_update_periodic) 3) decay_load_missed is called two times on every tick to eventually return immediately with no action taken. And that function is dead code. For pure optimization purposes, lets conditionally build the NO_HZ related code. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1461080211-16271-1-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Frederic Weisbecker
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1f41906a6f |
sched/fair: Correctly handle nohz ticks CPU load accounting
Ticks can happen while the CPU is in dynticks-idle or dynticks-singletask mode. In fact "nohz" or "dynticks" only mean that we exit the periodic mode and we try to minimize the ticks as much as possible. The nohz subsystem uses a confusing terminology with the internal state "ts->tick_stopped" which is also available through its public interface with tick_nohz_tick_stopped(). This is a misnomer as the tick is instead reduced with the best effort rather than stopped. In the best case the tick can indeed be actually stopped but there is no guarantee about that. If a timer needs to fire one second later, a tick will fire while the CPU is in nohz mode and this is a very common scenario. Now this confusion happens to be a problem with CPU load updates: cpu_load_update_active() doesn't handle nohz ticks correctly because it assumes that ticks are completely stopped in nohz mode and that cpu_load_update_active() can't be called in dynticks mode. When that happens, the whole previous tickless load is ignored and the function just records the load for the current tick, ignoring potentially long idle periods behind. In order to solve this, we could account the current load for the previous nohz time but there is a risk that we account the load of a task that got freshly enqueued for the whole nohz period. So instead, lets record the dynticks load on nohz frame entry so we know what to record in case of nohz ticks, then use this record to account the tickless load on nohz ticks and nohz frame end. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1460555812-25375-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Frederic Weisbecker
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cee1afce30 |
sched/fair: Gather CPU load functions under a more conventional namespace
The CPU load update related functions have a weak naming convention currently, starting with update_cpu_load_*() which isn't ideal as "update" is a very generic concept. Since two of these functions are public already (and a third is to come) that's enough to introduce a more conventional naming scheme. So let's do the following rename instead: update_cpu_load_*() -> cpu_load_update_*() Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1460555812-25375-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Steve Muckle
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a2c6c91f98 |
sched/fair: Call cpufreq hook in additional paths
The cpufreq hook should be called any time the root CFS rq utilization changes. This can occur when a task is switched to or from the fair class, or a task moves between groups or CPUs, but these paths currently do not call the cpufreq hook. Fix this by adding the hook to attach_entity_load_avg() and detach_entity_load_avg(). Suggested-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Steve Muckle <smuckle@linaro.org> [ Added the .update_freq argument to update_cfs_rq_load_avg() to avoid a double cpufreq call. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <Juri.Lelli@arm.com> Cc: Michael Turquette <mturquette@baylibre.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458858367-2831-1-git-send-email-smuckle@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Steve Muckle
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41e0d37f7a |
sched/fair: Do not call cpufreq hook unless util changed
There's no reason to call the cpufreq hook if the root cfs_rq utilization has not been modified. Signed-off-by: Steve Muckle <smuckle@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <Juri.Lelli@arm.com> Cc: Michael Turquette <mturquette@baylibre.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/1458606068-7476-2-git-send-email-smuckle@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Steve Muckle
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21e96f8877 |
sched/fair: Move cpufreq hook to update_cfs_rq_load_avg()
The cpufreq hook should be called whenever the root cfs_rq utilization changes so update_cfs_rq_load_avg() is a better place for it. The current location is not invoked in the enqueue_entity() or update_blocked_averages() paths. Suggested-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Steve Muckle <smuckle@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <Juri.Lelli@arm.com> Cc: Michael Turquette <mturquette@baylibre.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Patrick Bellasi <patrick.bellasi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458606068-7476-1-git-send-email-smuckle@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Srikar Dronamraju
|
1f621e028b |
sched/fair: Fix asym packing to select correct CPU
When asymmetric packing is set in the sched_domain and target CPU is busy, update_sd_pick_busiest() may not select the busiest runqueue. When target CPU is busy, find_busiest_group() will ignore checks for asym packing and may continue to load balance using the currently selected not-the-busiest runqueue as source runqueue. Selecting the busiest runqueue as source when the target CPU is busy, should result in achieving much better load balance. Also when target CPU is not busy and asymmetric packing is set in sd, select higher CPU as source CPU for load balancing. While doing this change, move the check to see if target CPU is busy into check_asym_packing(). The extent of performance benefit from this change decreases with the increasing load. However there is benefit in undercommit as well as overcommit conditions. 1. Record per second ebizzy (32 threads) on a 64 CPU power 7 box. (5 iterations) 4.6.0-rc2 Testcase: Min Max Avg StdDev ebizzy: 5223767.00 10368236.00 7946971.00 1753094.76 4.6.0-rc2+asym-changes Testcase: Min Max Avg StdDev %Change ebizzy: 8617191.00 13872356.00 11383980.00 1783400.89 +24.78% 2. Record per second ebizzy (64 threads) on a 64 CPU power 7 box. (5 iterations) 4.6.0-rc2 Testcase: Min Max Avg StdDev ebizzy: 6497666.00 18399783.00 10818093.20 4051452.08 4.6.0-rc2+asym-changes Testcase: Min Max Avg StdDev %Change ebizzy: 7567365.00 19456937.00 11674063.60 4295407.48 +4.40% 3. Record per second ebizzy (128 threads) on a 64 CPU power 7 box. (5 iterations) 4.6.0-rc2 Testcase: Min Max Avg StdDev ebizzy: 37073983.00 40341911.00 38776241.80 1259766.82 4.6.0-rc2+asym-changes Testcase: Min Max Avg StdDev %Change ebizzy: 38030399.00 41333378.00 39827404.40 1255001.86 +2.54% Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1459948660-16073-1-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Anton Blanchard
|
bd92883051 |
sched/cpuacct: Check for NULL when using task_pt_regs()
task_pt_regs() can return NULL for kernel threads, so add a check. This fixes an oops at boot on ppc64. Reported-and-Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Tested-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Zhao Lei <zhaolei@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: efault@gmx.de Cc: htejun@gmail.com Cc: linuxppc-dev@lists.ozlabs.org Cc: tj@kernel.org Cc: yangds.fnst@cn.fujitsu.com Link: http://lkml.kernel.org/r/20160406215950.04bc3f0b@kryten Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Daniel Lezcano
|
2c923e94cd |
sched/clock: Make local_clock()/cpu_clock() inline
The local_clock/cpu_clock functions were changed to prevent a double identical test with sched_clock_cpu() when HAVE_UNSTABLE_SCHED_CLOCK is set. That resulted in one line functions. As these functions are in all the cases one line functions and in the hot path, it is useful to specify them as static inline in order to give a strong hint to the compiler. After verification, it appears the compiler does not inline them without this hint. Change those functions to static inline. sched_clock_cpu() is called via the inlined local_clock()/cpu_clock() functions from sched.h. So any module code including sched.h will reference sched_clock_cpu(). Thus it must be exported with the EXPORT_SYMBOL_GPL macro. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1460385514-14700-2-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Daniel Lezcano
|
c78b17e28c |
sched/clock: Remove pointless test in cpu_clock/local_clock
In case the HAVE_UNSTABLE_SCHED_CLOCK config is set, the cpu_clock() version checks if sched_clock_stable() is not set and calls sched_clock_cpu(), otherwise it calls sched_clock(). sched_clock_cpu() checks also if sched_clock_stable() is set and, if true, calls sched_clock(). sched_clock() will be called in sched_clock_cpu() if sched_clock_stable() is true. Remove the duplicate test by directly calling sched_clock_cpu() and let the static key act in this function instead. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1460385514-14700-1-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Rabin Vincent
|
fb90a6e93c |
sched/debug: Don't dump sched debug info in SysRq-W
sysrq_sched_debug_show() can dump a lot of information. Don't print out all that if we're just trying to get a list of blocked tasks (SysRq-W). The information is still accessible with SysRq-T. Signed-off-by: Rabin Vincent <rabinv@axis.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1459777322-30902-1-git-send-email-rabin.vincent@axis.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Yuyang Du
|
2b8c41daba |
sched/fair: Initiate a new task's util avg to a bounded value
A new task's util_avg is set to full utilization of a CPU (100% time running). This accelerates a new task's utilization ramp-up, useful to boost its execution in early time. However, it may result in (insanely) high utilization for a transient time period when a flood of tasks are spawned. Importantly, it violates the "fundamentally bounded" CPU utilization, and its side effect is negative if we don't take any measure to bound it. This patch proposes an algorithm to address this issue. It has two methods to approach a sensible initial util_avg: (1) An expected (or average) util_avg based on its cfs_rq's util_avg: util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight (2) A trajectory of how successive new tasks' util develops, which gives 1/2 of the left utilization budget to a new task such that the additional util is noticeably large (when overall util is low) or unnoticeably small (when overall util is high enough). In the meantime, the aggregate utilization is well bounded: util_avg_cap = (1024 - cfs_rq->avg.util_avg) / 2^n where n denotes the nth task. If util_avg is larger than util_avg_cap, then the effective util is clamped to the util_avg_cap. Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Yuyang Du <yuyang.du@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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: bsegall@google.com Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: steve.muckle@linaro.org Link: http://lkml.kernel.org/r/1459283456-21682-1-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Yuyang Du
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1c3de5e19f |
sched/fair: Update comments after a variable rename
The following commit:
|
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Steven Rostedt
|
47252cfbac |
sched/core: Add preempt checks in preempt_schedule() code
While testing the tracer preemptoff, I hit this strange trace:
<...>-259 0...1 0us : schedule <-worker_thread
<...>-259 0d..1 0us : rcu_note_context_switch <-__schedule
<...>-259 0d..1 0us : rcu_sched_qs <-rcu_note_context_switch
<...>-259 0d..1 0us : rcu_preempt_qs <-rcu_note_context_switch
<...>-259 0d..1 0us : _raw_spin_lock <-__schedule
<...>-259 0d..1 0us : preempt_count_add <-_raw_spin_lock
<...>-259 0d..2 0us : do_raw_spin_lock <-_raw_spin_lock
<...>-259 0d..2 1us : deactivate_task <-__schedule
<...>-259 0d..2 1us : update_rq_clock.part.84 <-deactivate_task
<...>-259 0d..2 1us : dequeue_task_fair <-deactivate_task
<...>-259 0d..2 1us : dequeue_entity <-dequeue_task_fair
<...>-259 0d..2 1us : update_curr <-dequeue_entity
<...>-259 0d..2 1us : update_min_vruntime <-update_curr
<...>-259 0d..2 1us : cpuacct_charge <-update_curr
<...>-259 0d..2 1us : __rcu_read_lock <-cpuacct_charge
<...>-259 0d..2 1us : __rcu_read_unlock <-cpuacct_charge
<...>-259 0d..2 1us : clear_buddies <-dequeue_entity
<...>-259 0d..2 1us : account_entity_dequeue <-dequeue_entity
<...>-259 0d..2 2us : update_min_vruntime <-dequeue_entity
<...>-259 0d..2 2us : update_cfs_shares <-dequeue_entity
<...>-259 0d..2 2us : hrtick_update <-dequeue_task_fair
<...>-259 0d..2 2us : wq_worker_sleeping <-__schedule
<...>-259 0d..2 2us : kthread_data <-wq_worker_sleeping
<...>-259 0d..2 2us : pick_next_task_fair <-__schedule
<...>-259 0d..2 2us : check_cfs_rq_runtime <-pick_next_task_fair
<...>-259 0d..2 2us : pick_next_entity <-pick_next_task_fair
<...>-259 0d..2 2us : clear_buddies <-pick_next_entity
<...>-259 0d..2 2us : pick_next_entity <-pick_next_task_fair
<...>-259 0d..2 2us : clear_buddies <-pick_next_entity
<...>-259 0d..2 2us : set_next_entity <-pick_next_task_fair
<...>-259 0d..2 3us : put_prev_entity <-pick_next_task_fair
<...>-259 0d..2 3us : check_cfs_rq_runtime <-put_prev_entity
<...>-259 0d..2 3us : set_next_entity <-pick_next_task_fair
gnome-sh-1031 0d..2 3us : finish_task_switch <-__schedule
gnome-sh-1031 0d..2 3us : _raw_spin_unlock_irq <-finish_task_switch
gnome-sh-1031 0d..2 3us : do_raw_spin_unlock <-_raw_spin_unlock_irq
gnome-sh-1031 0...2 3us!: preempt_count_sub <-_raw_spin_unlock_irq
gnome-sh-1031 0...1 582us : do_raw_spin_lock <-_raw_spin_lock
gnome-sh-1031 0...1 583us : _raw_spin_unlock <-drm_gem_object_lookup
gnome-sh-1031 0...1 583us : do_raw_spin_unlock <-_raw_spin_unlock
gnome-sh-1031 0...1 583us : preempt_count_sub <-_raw_spin_unlock
gnome-sh-1031 0...1 584us : _raw_spin_unlock <-drm_gem_object_lookup
gnome-sh-1031 0...1 584us+: trace_preempt_on <-drm_gem_object_lookup
gnome-sh-1031 0...1 603us : <stack trace>
=> preempt_count_sub
=> _raw_spin_unlock
=> drm_gem_object_lookup
=> i915_gem_madvise_ioctl
=> drm_ioctl
=> do_vfs_ioctl
=> SyS_ioctl
=> entry_SYSCALL_64_fastpath
As I'm tracing preemption disabled, it seemed incorrect that the trace
would go across a schedule and report not being in the scheduler.
Looking into this I discovered the problem.
schedule() calls preempt_disable() but the preempt_schedule() calls
preempt_enable_notrace(). What happened above was that the gnome-shell
task was preempted on another CPU, migrated over to the idle cpu. The
tracer stared with idle calling schedule(), which called
preempt_disable(), but then gnome-shell finished, and it enabled
preemption with preempt_enable_notrace() that does stop the trace, even
though preemption was enabled.
The purpose of the preempt_disable_notrace() in the preempt_schedule()
is to prevent function tracing from going into an infinite loop.
Because function tracing can trace the preempt_enable/disable() calls
that are traced. The problem with function tracing is:
NEED_RESCHED set
preempt_schedule()
preempt_disable()
preempt_count_inc()
function trace (before incrementing preempt count)
preempt_disable_notrace()
preempt_enable_notrace()
sees NEED_RESCHED set
preempt_schedule() (repeat)
Now by breaking out the preempt off/on tracing into their own code:
preempt_disable_check() and preempt_enable_check(), we can add these to
the preempt_schedule() code. As preemption would then be disabled, even
if they were to be traced by the function tracer, the disabled
preemption would prevent the recursion.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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>
Link: http://lkml.kernel.org/r/20160321112339.6dc78ad6@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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Tim Chen
|
bfdb198ccd |
sched/numa: Remove unnecessary NUMA dequeue update from non-SMP kernels
In account_entity_enqueue(), we do not do account_numa_enqueue() as NUMA balancing is not needed for UP kernels. Hence, we should remove the account_numa_dequeue() call from account_entity_dequeue() for UP kernels. Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1454366879.21738.29.camel@schen9-desk2.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Srikar Dronamraju
|
d02c071183 |
sched/fair: Reset nr_balance_failed after active balancing
To force a task migration during active balancing, nr_balance_failed is set to cache_nice_tries + 1. However nr_balance_failed is not reset. As a side effect, the next regular load balance under the same sd, a cache hot task might be migrated, just because nr_balance_failed count is high. Resetting nr_balance_failed after a successful active balance ensures that a hot task is not unreasonably migrated. This can be verified by looking at othe number of hot task migrations reported by /proc/schedstat. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458735884-30105-1-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Dongsheng Yang
|
d740037fac |
sched/cpuacct: Split usage accounting into user_usage and sys_usage
Sometimes, cpuacct.usage is not detailed enough to see how much CPU usage a group had. We want to know how much time it used in user mode and how much in kernel mode. This patch introduces more files to give this information: # ls /sys/fs/cgroup/cpuacct/cpuacct.usage* /sys/fs/cgroup/cpuacct/cpuacct.usage /sys/fs/cgroup/cpuacct/cpuacct.usage_percpu /sys/fs/cgroup/cpuacct/cpuacct.usage_user /sys/fs/cgroup/cpuacct/cpuacct.usage_percpu_user /sys/fs/cgroup/cpuacct/cpuacct.usage_sys /sys/fs/cgroup/cpuacct/cpuacct.usage_percpu_sys ... while keeping the ABI with the existing counter. Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> [ Ported to newer kernels. ] Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/aa171da036b520b51c79549e9b3215d29473f19d.1458635566.git.zhaolei@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Zhao Lei
|
5ca3726af7 |
sched/cpuacct: Show all possible CPUs in cpuacct output
Current code show stats of online CPUs in cpuacct.statcpus, show stats of present cpus in cpuacct.usage(_percpu), and using present CPUs for setting cpuacct.usage. It will cause inconsistent result when a CPU is online or offline or hotpluged. We should always use possible CPUs to avoid above problem. Here are the contents of a cpuacct.usage_percpu sysfs file, on a 4 CPU system with maxcpus=32: Before the patch: # cat cpuacct.usage_percpu 2456565 411435 1052897 832584 After the patch: # cat cpuacct.usage_percpu 2456565 411435 1052897 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Tejun Heo <htejun@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a11d56cef12d0b4807f8be3a46bf9798c3014d59.1458635566.git.zhaolei@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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|
Frederic Weisbecker
|
5529578a27 |
locking/atomic, sched: Unexport fetch_or()
This patch functionally reverts: |
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Linus Torvalds
|
be53f58fa0 |
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar: "Misc fixes: a cgroup fix, a fair-scheduler migration accounting fix, a cputime fix and two cpuacct cleanups" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cpuacct: Simplify the cpuacct code sched/cpuacct: Rename parameter in cpuusage_write() for readability sched/fair: Add comments to explain select_idle_sibling() sched/fair: Fix fairness issue on migration sched/cgroup: Fix/cleanup cgroup teardown/init sched/cputime: Fix steal time accounting vs. CPU hotplug |
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Dmitry Vyukov
|
5c9a8750a6 |
kernel: add kcov code coverage
kcov provides code coverage collection for coverage-guided fuzzing (randomized testing). Coverage-guided fuzzing is a testing technique that uses coverage feedback to determine new interesting inputs to a system. A notable user-space example is AFL (http://lcamtuf.coredump.cx/afl/). However, this technique is not widely used for kernel testing due to missing compiler and kernel support. kcov does not aim to collect as much coverage as possible. It aims to collect more or less stable coverage that is function of syscall inputs. To achieve this goal it does not collect coverage in soft/hard interrupts and instrumentation of some inherently non-deterministic or non-interesting parts of kernel is disbled (e.g. scheduler, locking). Currently there is a single coverage collection mode (tracing), but the API anticipates additional collection modes. Initially I also implemented a second mode which exposes coverage in a fixed-size hash table of counters (what Quentin used in his original patch). I've dropped the second mode for simplicity. This patch adds the necessary support on kernel side. The complimentary compiler support was added in gcc revision 231296. We've used this support to build syzkaller system call fuzzer, which has found 90 kernel bugs in just 2 months: https://github.com/google/syzkaller/wiki/Found-Bugs We've also found 30+ bugs in our internal systems with syzkaller. Another (yet unexplored) direction where kcov coverage would greatly help is more traditional "blob mutation". For example, mounting a random blob as a filesystem, or receiving a random blob over wire. Why not gcov. Typical fuzzing loop looks as follows: (1) reset coverage, (2) execute a bit of code, (3) collect coverage, repeat. A typical coverage can be just a dozen of basic blocks (e.g. an invalid input). In such context gcov becomes prohibitively expensive as reset/collect coverage steps depend on total number of basic blocks/edges in program (in case of kernel it is about 2M). Cost of kcov depends only on number of executed basic blocks/edges. On top of that, kernel requires per-thread coverage because there are always background threads and unrelated processes that also produce coverage. With inlined gcov instrumentation per-thread coverage is not possible. kcov exposes kernel PCs and control flow to user-space which is insecure. But debugfs should not be mapped as user accessible. Based on a patch by Quentin Casasnovas. [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode'] [akpm@linux-foundation.org: unbreak allmodconfig] [akpm@linux-foundation.org: follow x86 Makefile layout standards] Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Zhao Lei
|
73e6aafd9e |
sched/cpuacct: Simplify the cpuacct code
- Use for() instead of while() loop in some functions to make the code simpler. - Use this_cpu_ptr() instead of per_cpu_ptr() to make the code cleaner and a bit faster. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/d8a7ef9592f55224630cb26dea239f05b6398a4e.1458187654.git.zhaolei@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Dongsheng Yang
|
1a736b77a3 |
sched/cpuacct: Rename parameter in cpuusage_write() for readability
The name of the 'reset' parameter to cpuusage_write() is quite confusing, because the only valid value we allow is '0', so !reset is actually the case that resets ... Rename it to 'val' and explain it in a comment that we only allow 0. Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: cgroups@vger.kernel.org Cc: tj@kernel.org Link: http://lkml.kernel.org/r/1450696483-2864-1-git-send-email-yangds.fnst@cn.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Matt Fleming
|
d4335581dc |
sched/fair: Add comments to explain select_idle_sibling()
It's not entirely obvious how the main loop in select_idle_sibling() works on first glance. Sprinkle a few comments to explain the design and intention behind the loop based on some conversations with Mike and Peter. Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.com> Cc: Mike Galbraith <mgalbraith@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1457535548-15329-1-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Peter Zijlstra
|
3a47d5124a |
sched/fair: Fix fairness issue on migration
Pavan reported that in the presence of very light tasks (or cgroups) the placement of migrated tasks can cause severe fairness issues. The problem is that enqueue_entity() places the task before it updates time, thereby it can place the task far in the past (remember that light tasks will shoot virtual time forward at a high speed, so in relation to the pre-existing light task, we can land far in the past). This is done because update_curr() needs the current task, and we might be placing the current task. The obvious solution is to differentiate between the current and any other task; placing the current before we update time, and placing any other task after, such that !curr tasks end up at the current moment in time, and not in the past. Reported-by: Pavan Kondeti <pkondeti@codeaurora.org> Tested-by: Pavan Kondeti <pkondeti@codeaurora.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Link: http://lkml.kernel.org/r/20160309120403.GK6344@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Peter Zijlstra
|
2f5177f0fd |
sched/cgroup: Fix/cleanup cgroup teardown/init
The CPU controller hasn't kept up with the various changes in the whole cgroup initialization / destruction sequence, and commit: |
||
|
Ingo Molnar
|
42e405f7b1 |
Merge branch 'linus' into sched/urgent, to pick up dependencies
Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Linus Torvalds
|
26660a4046 |
Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull 'objtool' stack frame validation from Ingo Molnar:
"This tree adds a new kernel build-time object file validation feature
(ONFIG_STACK_VALIDATION=y): kernel stack frame correctness validation.
It was written by and is maintained by Josh Poimboeuf.
The motivation: there's a category of hard to find kernel bugs, most
of them in assembly code (but also occasionally in C code), that
degrades the quality of kernel stack dumps/backtraces. These bugs are
hard to detect at the source code level. Such bugs result in
incorrect/incomplete backtraces most of time - but can also in some
rare cases result in crashes or other undefined behavior.
The build time correctness checking is done via the new 'objtool'
user-space utility that was written for this purpose and which is
hosted in the kernel repository in tools/objtool/. The tool's (very
simple) UI and source code design is shaped after Git and perf and
shares quite a bit of infrastructure with tools/perf (which tooling
infrastructure sharing effort got merged via perf and is already
upstream). Objtool follows the well-known kernel coding style.
Objtool does not try to check .c or .S files, it instead analyzes the
resulting .o generated machine code from first principles: it decodes
the instruction stream and interprets it. (Right now objtool supports
the x86-64 architecture.)
From tools/objtool/Documentation/stack-validation.txt:
"The kernel CONFIG_STACK_VALIDATION option enables a host tool named
objtool which runs at compile time. It has a "check" subcommand
which analyzes every .o file and ensures the validity of its stack
metadata. It enforces a set of rules on asm code and C inline
assembly code so that stack traces can be reliable.
Currently it only checks frame pointer usage, but there are plans to
add CFI validation for C files and CFI generation for asm files.
For each function, it recursively follows all possible code paths
and validates the correct frame pointer state at each instruction.
It also follows code paths involving special sections, like
.altinstructions, __jump_table, and __ex_table, which can add
alternative execution paths to a given instruction (or set of
instructions). Similarly, it knows how to follow switch statements,
for which gcc sometimes uses jump tables."
When this new kernel option is enabled (it's disabled by default), the
tool, if it finds any suspicious assembly code pattern, outputs
warnings in compiler warning format:
warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup
warning: objtool:__schedule()+0x3c0: duplicate frame pointer save
warning: objtool:__schedule()+0x3fd: sibling call from callable instruction with changed frame pointer
... so that scripts that pick up compiler warnings will notice them.
All known warnings triggered by the tool are fixed by the tree, most
of the commits in fact prepare the kernel to be warning-free. Most of
them are bugfixes or cleanups that stand on their own, but there are
also some annotations of 'special' stack frames for justified cases
such entries to JIT-ed code (BPF) or really special boot time code.
There are two other long-term motivations behind this tool as well:
- To improve the quality and reliability of kernel stack frames, so
that they can be used for optimized live patching.
- To create independent infrastructure to check the correctness of
CFI stack frames at build time. CFI debuginfo is notoriously
unreliable and we cannot use it in the kernel as-is without extra
checking done both on the kernel side and on the build side.
The quality of kernel stack frames matters to debuggability as well,
so IMO we can merge this without having to consider the live patching
or CFI debuginfo angle"
* 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
objtool: Only print one warning per function
objtool: Add several performance improvements
tools: Copy hashtable.h into tools directory
objtool: Fix false positive warnings for functions with multiple switch statements
objtool: Rename some variables and functions
objtool: Remove superflous INIT_LIST_HEAD
objtool: Add helper macros for traversing instructions
objtool: Fix false positive warnings related to sibling calls
objtool: Compile with debugging symbols
objtool: Detect infinite recursion
objtool: Prevent infinite recursion in noreturn detection
objtool: Detect and warn if libelf is missing and don't break the build
tools: Support relative directory path for 'O='
objtool: Support CROSS_COMPILE
x86/asm/decoder: Use explicitly signed chars
objtool: Enable stack metadata validation on 64-bit x86
objtool: Add CONFIG_STACK_VALIDATION option
objtool: Add tool to perform compile-time stack metadata validation
x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard
sched: Always inline context_switch()
...
|
||
|
Linus Torvalds
|
6b5f04b6cf |
Merge branch 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"cgroup changes for v4.6-rc1. No userland visible behavior changes in
this pull request. I'll send out a separate pull request for the
addition of cgroup namespace support.
- The biggest change is the revamping of cgroup core task migration
and controller handling logic. There are quite a few places where
controllers and tasks are manipulated. Previously, many of those
places implemented custom operations for each specific use case
assuming specific starting conditions. While this worked, it makes
the code fragile and difficult to follow.
The bulk of this pull request restructures these operations so that
most related operations are performed through common helpers which
implement recursive (subtrees are always processed consistently)
and idempotent (they make cgroup hierarchy converge to the target
state rather than performing operations assuming specific starting
conditions). This makes the code a lot easier to understand,
verify and extend.
- Implicit controller support is added. This is primarily for using
perf_event on the v2 hierarchy so that perf can match cgroup v2
path without requiring the user to do anything special. The kernel
portion of perf_event changes is acked but userland changes are
still pending review.
- cgroup_no_v1= boot parameter added to ease testing cgroup v2 in
certain environments.
- There is a regression introduced during v4.4 devel cycle where
attempts to migrate zombie tasks can mess up internal object
management. This was fixed earlier this week and included in this
pull request w/ stable cc'd.
- Misc non-critical fixes and improvements"
* 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (44 commits)
cgroup: avoid false positive gcc-6 warning
cgroup: ignore css_sets associated with dead cgroups during migration
Documentation: cgroup v2: Trivial heading correction.
cgroup: implement cgroup_subsys->implicit_on_dfl
cgroup: use css_set->mg_dst_cgrp for the migration target cgroup
cgroup: make cgroup[_taskset]_migrate() take cgroup_root instead of cgroup
cgroup: move migration destination verification out of cgroup_migrate_prepare_dst()
cgroup: fix incorrect destination cgroup in cgroup_update_dfl_csses()
cgroup: Trivial correction to reflect controller.
cgroup: remove stale item in cgroup-v1 document INDEX file.
cgroup: update css iteration in cgroup_update_dfl_csses()
cgroup: allocate 2x cgrp_cset_links when setting up a new root
cgroup: make cgroup_calc_subtree_ss_mask() take @this_ss_mask
cgroup: reimplement rebind_subsystems() using cgroup_apply_control() and friends
cgroup: use cgroup_apply_enable_control() in cgroup creation path
cgroup: combine cgroup_mutex locking and offline css draining
cgroup: factor out cgroup_{apply|finalize}_control() from cgroup_subtree_control_write()
cgroup: introduce cgroup_{save|propagate|restore}_control()
cgroup: make cgroup_drain_offline() and cgroup_apply_control_{disable|enable}() recursive
cgroup: factor out cgroup_apply_control_enable() from cgroup_subtree_control_write()
...
|
||
|
Linus Torvalds
|
ef504fa591 |
Merge branch 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue updates from Tejun Heo: "Three trivial workqueue changes" * 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Fix comment for work_on_cpu() sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() workqueue: Replace usage of init_name with dev_set_name() |
||
|
Linus Torvalds
|
277edbabf6 |
Power management and ACPI material for v4.6-rc1, part 1
- Redesign of cpufreq governors and the intel_pstate driver to
make them use callbacks invoked by the scheduler to trigger CPU
frequency evaluation instead of using per-CPU deferrable timers
for that purpose (Rafael Wysocki).
- Reorganization and cleanup of cpufreq governor code to make it
more straightforward and fix some concurrency problems in it
(Rafael Wysocki, Viresh Kumar).
- Cleanup and improvements of locking in the cpufreq core (Viresh
Kumar).
- Assorted cleanups in the cpufreq core (Rafael Wysocki, Viresh
Kumar, Eric Biggers).
- intel_pstate driver updates including fixes, optimizations and a
modification to make it enable enable hardware-coordinated P-state
selection (HWP) by default if supported by the processor (Philippe
Longepe, Srinivas Pandruvada, Rafael Wysocki, Viresh Kumar, Felipe
Franciosi).
- Operating Performance Points (OPP) framework updates to improve
its handling of voltage regulators and device clocks and updates
of the cpufreq-dt driver on top of that (Viresh Kumar, Jon Hunter).
- Updates of the powernv cpufreq driver to fix initialization
and cleanup problems in it and correct its worker thread handling
with respect to CPU offline, new powernv_throttle tracepoint
(Shilpasri Bhat).
- ACPI cpufreq driver optimization and cleanup (Rafael Wysocki).
- ACPICA updates including one fix for a regression introduced
by previos changes in the ACPICA code (Bob Moore, Lv Zheng,
David Box, Colin Ian King).
- Support for installing ACPI tables from initrd (Lv Zheng).
- Optimizations of the ACPI CPPC code (Prashanth Prakash, Ashwin
Chaugule).
- Support for _HID(ACPI0010) devices (ACPI processor containers)
and ACPI processor driver cleanups (Sudeep Holla).
- Support for ACPI-based enumeration of the AMBA bus (Graeme Gregory,
Aleksey Makarov).
- Modification of the ACPI PCI IRQ management code to make it treat
255 in the Interrupt Line register as "not connected" on x86 (as
per the specification) and avoid attempts to use that value as
a valid interrupt vector (Chen Fan).
- ACPI APEI fixes related to resource leaks (Josh Hunt).
- Removal of modularity from a few ACPI drivers (BGRT, GHES,
intel_pmic_crc) that cannot be built as modules in practice (Paul
Gortmaker).
- PNP framework update to make it treat ACPI_RESOURCE_TYPE_SERIAL_BUS
as a valid resource type (Harb Abdulhamid).
- New device ID (future AMD I2C controller) in the ACPI driver for
AMD SoCs (APD) and in the designware I2C driver (Xiangliang Yu).
- Assorted ACPI cleanups (Colin Ian King, Kaiyen Chang, Oleg Drokin).
- cpuidle menu governor optimization to avoid a square root
computation in it (Rasmus Villemoes).
- Fix for potential use-after-free in the generic device properties
framework (Heikki Krogerus).
- Updates of the generic power domains (genpd) framework including
support for multiple power states of a domain, fixes and debugfs
output improvements (Axel Haslam, Jon Hunter, Laurent Pinchart,
Geert Uytterhoeven).
- Intel RAPL power capping driver updates to reduce IPI overhead in
it (Jacob Pan).
- System suspend/hibernation code cleanups (Eric Biggers, Saurabh
Sengar).
- Year 2038 fix for the process freezer (Abhilash Jindal).
- turbostat utility updates including new features (decoding of more
registers and CPUID fields, sub-second intervals support, GFX MHz
and RC6 printout, --out command line option), fixes (syscall jitter
detection and workaround, reductioin of the number of syscalls made,
fixes related to Xeon x200 processors, compiler warning fixes) and
cleanups (Len Brown, Hubert Chrzaniuk, Chen Yu).
/
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Merge tag 'pm+acpi-4.6-rc1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management and ACPI updates from Rafael Wysocki:
"This time the majority of changes go into cpufreq and they are
significant.
First off, the way CPU frequency updates are triggered is different
now. Instead of having to set up and manage a deferrable timer for
each CPU in the system to evaluate and possibly change its frequency
periodically, cpufreq governors set up callbacks to be invoked by the
scheduler on a regular basis (basically on utilization updates). The
"old" governors, "ondemand" and "conservative", still do all of their
work in process context (although that is triggered by the scheduler
now), but intel_pstate does it all in the callback invoked by the
scheduler with no need for any additional asynchronous processing.
Of course, this eliminates the overhead related to the management of
all those timers, but also it allows the cpufreq governor code to be
simplified quite a bit. On top of that, the common code and data
structures used by the "ondemand" and "conservative" governors are
cleaned up and made more straightforward and some long-standing and
quite annoying problems are addressed. In particular, the handling of
governor sysfs attributes is modified and the related locking becomes
more fine grained which allows some concurrency problems to be avoided
(particularly deadlocks with the core cpufreq code).
In principle, the new mechanism for triggering frequency updates
allows utilization information to be passed from the scheduler to
cpufreq. Although the current code doesn't make use of it, in the
works is a new cpufreq governor that will make decisions based on the
scheduler's utilization data. That should allow the scheduler and
cpufreq to work more closely together in the long run.
In addition to the core and governor changes, cpufreq drivers are
updated too. Fixes and optimizations go into intel_pstate, the
cpufreq-dt driver is updated on top of some modification in the
Operating Performance Points (OPP) framework and there are fixes and
other updates in the powernv cpufreq driver.
Apart from the cpufreq updates there is some new ACPICA material,
including a fix for a problem introduced by previous ACPICA updates,
and some less significant changes in the ACPI code, like CPPC code
optimizations, ACPI processor driver cleanups and support for loading
ACPI tables from initrd.
Also updated are the generic power domains framework, the Intel RAPL
power capping driver and the turbostat utility and we have a bunch of
traditional assorted fixes and cleanups.
Specifics:
- Redesign of cpufreq governors and the intel_pstate driver to make
them use callbacks invoked by the scheduler to trigger CPU
frequency evaluation instead of using per-CPU deferrable timers for
that purpose (Rafael Wysocki).
- Reorganization and cleanup of cpufreq governor code to make it more
straightforward and fix some concurrency problems in it (Rafael
Wysocki, Viresh Kumar).
- Cleanup and improvements of locking in the cpufreq core (Viresh
Kumar).
- Assorted cleanups in the cpufreq core (Rafael Wysocki, Viresh
Kumar, Eric Biggers).
- intel_pstate driver updates including fixes, optimizations and a
modification to make it enable enable hardware-coordinated P-state
selection (HWP) by default if supported by the processor (Philippe
Longepe, Srinivas Pandruvada, Rafael Wysocki, Viresh Kumar, Felipe
Franciosi).
- Operating Performance Points (OPP) framework updates to improve its
handling of voltage regulators and device clocks and updates of the
cpufreq-dt driver on top of that (Viresh Kumar, Jon Hunter).
- Updates of the powernv cpufreq driver to fix initialization and
cleanup problems in it and correct its worker thread handling with
respect to CPU offline, new powernv_throttle tracepoint (Shilpasri
Bhat).
- ACPI cpufreq driver optimization and cleanup (Rafael Wysocki).
- ACPICA updates including one fix for a regression introduced by
previos changes in the ACPICA code (Bob Moore, Lv Zheng, David Box,
Colin Ian King).
- Support for installing ACPI tables from initrd (Lv Zheng).
- Optimizations of the ACPI CPPC code (Prashanth Prakash, Ashwin
Chaugule).
- Support for _HID(ACPI0010) devices (ACPI processor containers) and
ACPI processor driver cleanups (Sudeep Holla).
- Support for ACPI-based enumeration of the AMBA bus (Graeme Gregory,
Aleksey Makarov).
- Modification of the ACPI PCI IRQ management code to make it treat
255 in the Interrupt Line register as "not connected" on x86 (as
per the specification) and avoid attempts to use that value as a
valid interrupt vector (Chen Fan).
- ACPI APEI fixes related to resource leaks (Josh Hunt).
- Removal of modularity from a few ACPI drivers (BGRT, GHES,
intel_pmic_crc) that cannot be built as modules in practice (Paul
Gortmaker).
- PNP framework update to make it treat ACPI_RESOURCE_TYPE_SERIAL_BUS
as a valid resource type (Harb Abdulhamid).
- New device ID (future AMD I2C controller) in the ACPI driver for
AMD SoCs (APD) and in the designware I2C driver (Xiangliang Yu).
- Assorted ACPI cleanups (Colin Ian King, Kaiyen Chang, Oleg Drokin).
- cpuidle menu governor optimization to avoid a square root
computation in it (Rasmus Villemoes).
- Fix for potential use-after-free in the generic device properties
framework (Heikki Krogerus).
- Updates of the generic power domains (genpd) framework including
support for multiple power states of a domain, fixes and debugfs
output improvements (Axel Haslam, Jon Hunter, Laurent Pinchart,
Geert Uytterhoeven).
- Intel RAPL power capping driver updates to reduce IPI overhead in
it (Jacob Pan).
- System suspend/hibernation code cleanups (Eric Biggers, Saurabh
Sengar).
- Year 2038 fix for the process freezer (Abhilash Jindal).
- turbostat utility updates including new features (decoding of more
registers and CPUID fields, sub-second intervals support, GFX MHz
and RC6 printout, --out command line option), fixes (syscall jitter
detection and workaround, reductioin of the number of syscalls
made, fixes related to Xeon x200 processors, compiler warning
fixes) and cleanups (Len Brown, Hubert Chrzaniuk, Chen Yu)"
* tag 'pm+acpi-4.6-rc1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (182 commits)
tools/power turbostat: bugfix: TDP MSRs print bits fixing
tools/power turbostat: correct output for MSR_NHM_SNB_PKG_CST_CFG_CTL dump
tools/power turbostat: call __cpuid() instead of __get_cpuid()
tools/power turbostat: indicate SMX and SGX support
tools/power turbostat: detect and work around syscall jitter
tools/power turbostat: show GFX%rc6
tools/power turbostat: show GFXMHz
tools/power turbostat: show IRQs per CPU
tools/power turbostat: make fewer systems calls
tools/power turbostat: fix compiler warnings
tools/power turbostat: add --out option for saving output in a file
tools/power turbostat: re-name "%Busy" field to "Busy%"
tools/power turbostat: Intel Xeon x200: fix turbo-ratio decoding
tools/power turbostat: Intel Xeon x200: fix erroneous bclk value
tools/power turbostat: allow sub-sec intervals
ACPI / APEI: ERST: Fixed leaked resources in erst_init
ACPI / APEI: Fix leaked resources
intel_pstate: Do not skip samples partially
intel_pstate: Remove freq calculation from intel_pstate_calc_busy()
intel_pstate: Move intel_pstate_calc_busy() into get_target_pstate_use_performance()
...
|
||
|
Linus Torvalds
|
710d60cbf1 |
Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull cpu hotplug updates from Thomas Gleixner:
"This is the first part of the ongoing cpu hotplug rework:
- Initial implementation of the state machine
- Runs all online and prepare down callbacks on the plugged cpu and
not on some random processor
- Replaces busy loop waiting with completions
- Adds tracepoints so the states can be followed"
More detailed commentary on this work from an earlier email:
"What's wrong with the current cpu hotplug infrastructure?
- Asymmetry
The hotplug notifier mechanism is asymmetric versus the bringup and
teardown. This is mostly caused by the notifier mechanism.
- Largely undocumented dependencies
While some notifiers use explicitely defined notifier priorities,
we have quite some notifiers which use numerical priorities to
express dependencies without any documentation why.
- Control processor driven
Most of the bringup/teardown of a cpu is driven by a control
processor. While it is understandable, that preperatory steps,
like idle thread creation, memory allocation for and initialization
of essential facilities needs to be done before a cpu can boot,
there is no reason why everything else must run on a control
processor. Before this patch series, bringup looks like this:
Control CPU Booting CPU
do preparatory steps
kick cpu into life
do low level init
sync with booting cpu sync with control cpu
bring the rest up
- All or nothing approach
There is no way to do partial bringups. That's something which is
really desired because we waste e.g. at boot substantial amount of
time just busy waiting that the cpu comes to life. That's stupid
as we could very well do preparatory steps and the initial IPI for
other cpus and then go back and do the necessary low level
synchronization with the freshly booted cpu.
- Minimal debuggability
Due to the notifier based design, it's impossible to switch between
two stages of the bringup/teardown back and forth in order to test
the correctness. So in many hotplug notifiers the cancel
mechanisms are either not existant or completely untested.
- Notifier [un]registering is tedious
To [un]register notifiers we need to protect against hotplug at
every callsite. There is no mechanism that bringup/teardown
callbacks are issued on the online cpus, so every caller needs to
do it itself. That also includes error rollback.
What's the new design?
The base of the new design is a symmetric state machine, where both
the control processor and the booting/dying cpu execute a well
defined set of states. Each state is symmetric in the end, except
for some well defined exceptions, and the bringup/teardown can be
stopped and reversed at almost all states.
So the bringup of a cpu will look like this in the future:
Control CPU Booting CPU
do preparatory steps
kick cpu into life
do low level init
sync with booting cpu sync with control cpu
bring itself up
The synchronization step does not require the control cpu to wait.
That mechanism can be done asynchronously via a worker or some
other mechanism.
The teardown can be made very similar, so that the dying cpu cleans
up and brings itself down. Cleanups which need to be done after
the cpu is gone, can be scheduled asynchronously as well.
There is a long way to this, as we need to refactor the notion when a
cpu is available. Today we set the cpu online right after it comes
out of the low level bringup, which is not really correct.
The proper mechanism is to set it to available, i.e. cpu local
threads, like softirqd, hotplug thread etc. can be scheduled on that
cpu, and once it finished all booting steps, it's set to online, so
general workloads can be scheduled on it. The reverse happens on
teardown. First thing to do is to forbid scheduling of general
workloads, then teardown all the per cpu resources and finally shut it
off completely.
This patch series implements the basic infrastructure for this at the
core level. This includes the following:
- Basic state machine implementation with well defined states, so
ordering and prioritization can be expressed.
- Interfaces to [un]register state callbacks
This invokes the bringup/teardown callback on all online cpus with
the proper protection in place and [un]installs the callbacks in
the state machine array.
For callbacks which have no particular ordering requirement we have
a dynamic state space, so that drivers don't have to register an
explicit hotplug state.
If a callback fails, the code automatically does a rollback to the
previous state.
- Sysfs interface to drive the state machine to a particular step.
This is only partially functional today. Full functionality and
therefor testability will be achieved once we converted all
existing hotplug notifiers over to the new scheme.
- Run all CPU_ONLINE/DOWN_PREPARE notifiers on the booting/dying
processor:
Control CPU Booting CPU
do preparatory steps
kick cpu into life
do low level init
sync with booting cpu sync with control cpu
wait for boot
bring itself up
Signal completion to control cpu
In a previous step of this work we've done a full tree mechanical
conversion of all hotplug notifiers to the new scheme. The balance
is a net removal of about 4000 lines of code.
This is not included in this series, as we decided to take a
different approach. Instead of mechanically converting everything
over, we will do a proper overhaul of the usage sites one by one so
they nicely fit into the symmetric callback scheme.
I decided to do that after I looked at the ugliness of some of the
converted sites and figured out that their hotplug mechanism is
completely buggered anyway. So there is no point to do a
mechanical conversion first as we need to go through the usage
sites one by one again in order to achieve a full symmetric and
testable behaviour"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
cpu/hotplug: Document states better
cpu/hotplug: Fix smpboot thread ordering
cpu/hotplug: Remove redundant state check
cpu/hotplug: Plug death reporting race
rcu: Make CPU_DYING_IDLE an explicit call
cpu/hotplug: Make wait for dead cpu completion based
cpu/hotplug: Let upcoming cpu bring itself fully up
arch/hotplug: Call into idle with a proper state
cpu/hotplug: Move online calls to hotplugged cpu
cpu/hotplug: Create hotplug threads
cpu/hotplug: Split out the state walk into functions
cpu/hotplug: Unpark smpboot threads from the state machine
cpu/hotplug: Move scheduler cpu_online notifier to hotplug core
cpu/hotplug: Implement setup/removal interface
cpu/hotplug: Make target state writeable
cpu/hotplug: Add sysfs state interface
cpu/hotplug: Hand in target state to _cpu_up/down
cpu/hotplug: Convert the hotplugged cpu work to a state machine
cpu/hotplug: Convert to a state machine for the control processor
cpu/hotplug: Add tracepoints
...
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