sched/fair: Reduce the periodic update duration (1936c53c) · Commits · 戴 / test

Instead of using the cfs_rq_is_decayed() which monitors all *_avg and *_sum, we create a cfs_rq_has_blocked() which only takes care of util_avg and load_avg. We are only interested by these 2 values which are decaying faster than the *_sum so we can stop the periodic update earlier. Signed-off-by:

Vincent Guittot <vincent.guittot@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: brendan.jackman@arm.com Cc: dietmar.eggemann@arm.com Cc: morten.rasmussen@foss.arm.com Cc: valentin.schneider@arm.com Link: http://lkml.kernel.org/r/1518517879-2280-3-git-send-email-vincent.guittot@linaro.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

+17 −4

Original line number	Diff line number	Diff line
		@@ -7424,6 +7424,19 @@ static void attach_tasks(struct lb_env *env)
		rq_unlock(env->dst_rq, &rf);
		}

		static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
		{
		if (cfs_rq->avg.load_avg)
		return true;

		if (cfs_rq->avg.util_avg)
		return true;

		return false;
		}

		#ifdef CONFIG_FAIR_GROUP_SCHED

		static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
		{
		if (cfs_rq->load.weight)
		@@ -7441,8 +7454,6 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
		return true;
		}

		#ifdef CONFIG_FAIR_GROUP_SCHED

		static void update_blocked_averages(int cpu)
		{
		struct rq *rq = cpu_rq(cpu);
		@@ -7478,7 +7489,9 @@ static void update_blocked_averages(int cpu)
		*/
		if (cfs_rq_is_decayed(cfs_rq))
		list_del_leaf_cfs_rq(cfs_rq);
		else

		/* Don't need periodic decay once load/util_avg are null */
		if (cfs_rq_has_blocked(cfs_rq))
		done = false;
		}

		@@ -7548,7 +7561,7 @@ static inline void update_blocked_averages(int cpu)
		update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);
		#ifdef CONFIG_NO_HZ_COMMON
		rq->last_blocked_load_update_tick = jiffies;
		if (cfs_rq_is_decayed(cfs_rq))
		if (!cfs_rq_has_blocked(cfs_rq))
		rq->has_blocked_load = 0;
		#endif
		rq_unlock_irqrestore(rq, &rf);

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