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Commit 594dd290 authored by Wanpeng Li's avatar Wanpeng Li Committed by Ingo Molnar
Browse files

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: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent fec148c0

kernel/sched/deadline.c

+4 −4
Original line number Diff line number Diff line
@@ -717,10 +717,6 @@ static void update_curr_dl(struct rq *rq) 
	if (!dl_task(curr) || !on_dl_rq(dl_se))

		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

	 * observed by schedulable tasks (excluding time spent
@@ -736,6 +732,10 @@ static void update_curr_dl(struct rq *rq) 
		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,

		      max(curr->se.statistics.exec_max, delta_exec));

kernel/sched/rt.c

+4 −4
Original line number Diff line number Diff line
@@ -953,14 +953,14 @@ static void update_curr_rt(struct rq *rq) 
	if (curr->sched_class != &rt_sched_class)

		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;

	if (unlikely((s64)delta_exec <= 0))

		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,

		      max(curr->se.statistics.exec_max, delta_exec));