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Groups > linux.kernel > #1223593
| From | tip-bot for Dietmar Eggemann <tipbot@zytor.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [tip:sched/core] sched/fair: Get rid of scaling utilization by capacity_orig |
| Date | 2015-09-13 13:10 +0200 |
| Message-ID | <q8dkv-5Qt-39@gated-at.bofh.it> (permalink) |
| References | <q66Gt-1eb-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Commit-ID: 231678b768da07d19ab5683a39eeb0c250631d02
Gitweb: http://git.kernel.org/tip/231678b768da07d19ab5683a39eeb0c250631d02
Author: Dietmar Eggemann <dietmar.eggemann@arm.com>
AuthorDate: Fri, 14 Aug 2015 17:23:13 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 13 Sep 2015 09:52:57 +0200
sched/fair: Get rid of scaling utilization by capacity_orig
Utilization is currently scaled by capacity_orig, but since we now have
frequency and cpu invariant cfs_rq.avg.util_avg, frequency and cpu scaling
now happens as part of the utilization tracking itself.
So cfs_rq.avg.util_avg should no longer be scaled in cpu_util().
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <Juri.Lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Muckle <steve.muckle@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: daniel.lezcano@linaro.org <daniel.lezcano@linaro.org>
Cc: mturquette@baylibre.com <mturquette@baylibre.com>
Cc: pang.xunlei@zte.com.cn <pang.xunlei@zte.com.cn>
Cc: rjw@rjwysocki.net <rjw@rjwysocki.net>
Cc: sgurrappadi@nvidia.com <sgurrappadi@nvidia.com>
Cc: vincent.guittot@linaro.org <vincent.guittot@linaro.org>
Cc: yuyang.du@intel.com <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/55EDAF43.30500@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/fair.c | 38 ++++++++++++++++++++++----------------
1 file changed, 22 insertions(+), 16 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1b56d63..047fd1c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4862,33 +4862,39 @@ next:
done:
return target;
}
+
/*
* cpu_util returns the amount of capacity of a CPU that is used by CFS
* tasks. The unit of the return value must be the one of capacity so we can
* compare the utilization with the capacity of the CPU that is available for
* CFS task (ie cpu_capacity).
- * cfs.avg.util_avg is the sum of running time of runnable tasks on a
- * CPU. It represents the amount of utilization of a CPU in the range
- * [0..SCHED_LOAD_SCALE]. The utilization of a CPU can't be higher than the
- * full capacity of the CPU because it's about the running time on this CPU.
- * Nevertheless, cfs.avg.util_avg can be higher than SCHED_LOAD_SCALE
- * because of unfortunate rounding in util_avg or just
- * after migrating tasks until the average stabilizes with the new running
- * time. So we need to check that the utilization stays into the range
- * [0..cpu_capacity_orig] and cap if necessary.
- * Without capping the utilization, a group could be seen as overloaded (CPU0
- * utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of
- * available capacity.
+ *
+ * cfs_rq.avg.util_avg is the sum of running time of runnable tasks plus the
+ * recent utilization of currently non-runnable tasks on a CPU. It represents
+ * the amount of utilization of a CPU in the range [0..capacity_orig] where
+ * capacity_orig is the cpu_capacity available at the highest frequency
+ * (arch_scale_freq_capacity()).
+ * The utilization of a CPU converges towards a sum equal to or less than the
+ * current capacity (capacity_curr <= capacity_orig) of the CPU because it is
+ * the running time on this CPU scaled by capacity_curr.
+ *
+ * Nevertheless, cfs_rq.avg.util_avg can be higher than capacity_curr or even
+ * higher than capacity_orig because of unfortunate rounding in
+ * cfs.avg.util_avg or just after migrating tasks and new task wakeups until
+ * the average stabilizes with the new running time. We need to check that the
+ * utilization stays within the range of [0..capacity_orig] and cap it if
+ * necessary. Without utilization capping, a group could be seen as overloaded
+ * (CPU0 utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of
+ * available capacity. We allow utilization to overshoot capacity_curr (but not
+ * capacity_orig) as it useful for predicting the capacity required after task
+ * migrations (scheduler-driven DVFS).
*/
static int cpu_util(int cpu)
{
unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg;
unsigned long capacity = capacity_orig_of(cpu);
- if (util >= SCHED_LOAD_SCALE)
- return capacity;
-
- return (util * capacity) >> SCHED_LOAD_SHIFT;
+ return (util >= capacity) ? capacity : util;
}
/*
--
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Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-07 17:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-07 18:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-07 21:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-07 21:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 14:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 09:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 14:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 15:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 16:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 16:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 17:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-10 00:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-10 13:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-10 13:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-10 14:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-11 10:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-10 19:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-08 18:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-09 11:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-09 11:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-09 13:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 19:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-17 12:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-17 12:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-21 11:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-21 19:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-22 09:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Leo Yan <leo.yan@linaro.org> - 2015-09-11 09:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 12:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Leo Yan <leo.yan@linaro.org> - 2015-09-11 16:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-10 05:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-10 12:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 15:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 16:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 17:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 15:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Vincent Guittot <vincent.guittot@linaro.org> - 2015-09-08 16:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Dietmar Eggemann <dietmar.eggemann@arm.com> - 2015-09-08 16:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-10 06:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-10 12:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-11 10:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-11 12:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-11 19:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-12 04:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-14 19:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-14 15:00 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-14 19:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-15 08:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-15 19:20 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-16 04:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig bsegall@google.com - 2015-09-16 19:10 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Yuyang Du <yuyang.du@intel.com> - 2015-09-17 12:30 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Morten Rasmussen <morten.rasmussen@arm.com> - 2015-09-15 10:40 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-16 17:50 +0200
Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig Peter Zijlstra <peterz@infradead.org> - 2015-09-08 13:50 +0200
[tip:sched/core] sched/fair: Get rid of scaling utilization by capacity_orig tip-bot for Dietmar Eggemann <tipbot@zytor.com> - 2015-09-13 13:10 +0200
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