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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>
This commit is contained in:
Wanpeng Li 2016-04-22 17:07:24 +08:00 committed by Ingo Molnar
parent fec148c000
commit 594dd290cf
2 changed files with 8 additions and 8 deletions
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8
kernel/sched/deadline.c
View File

@ -717,10 +717,6 @@ static void update_curr_dl(struct rq *rq)
if (!dl_task(curr) || !on_dl_rq(dl_se)) if (!dl_task(curr) || !on_dl_rq(dl_se))
return; return;
/* Kick cpufreq (see the comment in linux/cpufreq.h). */
if (cpu_of(rq) == smp_processor_id())
cpufreq_trigger_update(rq_clock(rq));
/* /*
* Consumed budget is computed considering the time as * Consumed budget is computed considering the time as
* observed by schedulable tasks (excluding time spent * observed by schedulable tasks (excluding time spent
@ -736,6 +732,10 @@ static void update_curr_dl(struct rq *rq)
return; return;
} }
/* kick cpufreq (see the comment in linux/cpufreq.h). */
if (cpu_of(rq) == smp_processor_id())
cpufreq_trigger_update(rq_clock(rq));
schedstat_set(curr->se.statistics.exec_max, schedstat_set(curr->se.statistics.exec_max,
max(curr->se.statistics.exec_max, delta_exec)); max(curr->se.statistics.exec_max, delta_exec));

8
kernel/sched/rt.c
View File

@ -953,14 +953,14 @@ static void update_curr_rt(struct rq *rq)
if (curr->sched_class != &rt_sched_class) if (curr->sched_class != &rt_sched_class)
return; return;
/* Kick cpufreq (see the comment in linux/cpufreq.h). */
if (cpu_of(rq) == smp_processor_id())
cpufreq_trigger_update(rq_clock(rq));
delta_exec = rq_clock_task(rq) - curr->se.exec_start; delta_exec = rq_clock_task(rq) - curr->se.exec_start;
if (unlikely((s64)delta_exec <= 0)) if (unlikely((s64)delta_exec <= 0))
return; return;
/* Kick cpufreq (see the comment in linux/cpufreq.h). */
if (cpu_of(rq) == smp_processor_id())
cpufreq_trigger_update(rq_clock(rq));
schedstat_set(curr->se.statistics.exec_max, schedstat_set(curr->se.statistics.exec_max,
max(curr->se.statistics.exec_max, delta_exec)); max(curr->se.statistics.exec_max, delta_exec));