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sched/fair: Call cpufreq update util handlers less frequently on UP 

For SMP systems, update_load_avg() calls the cpufreq update util
handlers only for the top level cfs_rq (i.e. rq->cfs).

But that is not the case for UP systems. update_load_avg() calls util
handler for any cfs_rq for which it is called. This would result in way
too many calls from the scheduler to the cpufreq governors when
CONFIG_FAIR_GROUP_SCHED is enabled.

Reduce the frequency of these calls by copying the behavior from the SMP
case, i.e. Only call util handlers for the top level cfs_rq.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Fixes: 536bd00cdb ("sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage")
Link: http://lkml.kernel.org/r/6abf69a2107525885b616a2c1ec03d9c0946171c.1495603536.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Viresh Kumar 2017-05-24 10:59:52 +05:30 committed by Ingo Molnar
parent fc33a8943e
commit a030d7381d
1 changed files with 24 additions and 24 deletions
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48
kernel/sched/fair.c
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@ -2790,6 +2790,29 @@ static inline void update_cfs_shares(struct sched_entity *se)
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq)
{
if (&this_rq()->cfs == cfs_rq) {
/*
* There are a few boundary cases this might miss but it should
* get called often enough that that should (hopefully) not be
* a real problem -- added to that it only calls on the local
* CPU, so if we enqueue remotely we'll miss an update, but
* the next tick/schedule should update.
*
* It will not get called when we go idle, because the idle
* thread is a different class (!fair), nor will the utilization
* number include things like RT tasks.
*
* As is, the util number is not freq-invariant (we'd have to
* implement arch_scale_freq_capacity() for that).
*
* See cpu_util().
*/
cpufreq_update_util(rq_of(cfs_rq), 0);
}
}
#ifdef CONFIG_SMP
/*
* Approximate:
@ -3276,29 +3299,6 @@ static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
#endif /* CONFIG_FAIR_GROUP_SCHED */
static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq)
{
if (&this_rq()->cfs == cfs_rq) {
/*
* There are a few boundary cases this might miss but it should
* get called often enough that that should (hopefully) not be
* a real problem -- added to that it only calls on the local
* CPU, so if we enqueue remotely we'll miss an update, but
* the next tick/schedule should update.
*
* It will not get called when we go idle, because the idle
* thread is a different class (!fair), nor will the utilization
* number include things like RT tasks.
*
* As is, the util number is not freq-invariant (we'd have to
* implement arch_scale_freq_capacity() for that).
*
* See cpu_util().
*/
cpufreq_update_util(rq_of(cfs_rq), 0);
}
}
/*
* Unsigned subtract and clamp on underflow.
*
@ -3544,7 +3544,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
static inline void update_load_avg(struct sched_entity *se, int not_used1)
{
cpufreq_update_util(rq_of(cfs_rq_of(se)), 0);
cfs_rq_util_change(cfs_rq_of(se));
}
static inline void