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Commit 63928384 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/nohz: Optimize nohz_idle_balance() 



Avoid calling update_blocked_averages() when it does not in fact have
any by re-using/extending update_nohz_stats().

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1936c53c

kernel/sched/fair.c

+4 −5
Original line number Diff line number Diff line
@@ -7898,7 +7898,7 @@ group_type group_classify(struct sched_group *group, 
	return group_other;

}



static bool update_nohz_stats(struct rq *rq)

static bool update_nohz_stats(struct rq *rq, bool force)

{

#ifdef CONFIG_NO_HZ_COMMON

	unsigned int cpu = rq->cpu;
@@ -7909,7 +7909,7 @@ static bool update_nohz_stats(struct rq *rq) 
	if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))

		return false;



	if (!time_after(jiffies, rq->last_blocked_load_update_tick))

	if (!force && !time_after(jiffies, rq->last_blocked_load_update_tick))

		return true;



	update_blocked_averages(cpu);
@@ -7942,7 +7942,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, 
	for_each_cpu_and(i, sched_group_span(group), env->cpus) {

		struct rq *rq = cpu_rq(i);



		if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq))

		if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq, false))

			env->flags |= LBF_NOHZ_AGAIN;



		/* Bias balancing toward CPUs of our domain: */
@@ -9552,8 +9552,7 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) 


		rq = cpu_rq(balance_cpu);



		update_blocked_averages(rq->cpu);

		has_blocked_load |= rq->has_blocked_load;

		has_blocked_load |= update_nohz_stats(rq, true);



		/*

		 * If time for next balance is due,