sched/rt: Fix call to cpufreq_update_util() (296b2ffe) · Commits · 戴 / test

With commit: ("cpufreq/schedutil: Rewrite CPUFREQ_RT support") the schedutil governor uses rq->rt.rt_nr_running to detect whether an RT task is currently running on the CPU and to set frequency to max if necessary. cpufreq_update_util() is called in enqueue/dequeue_top_rt_rq() but rq->rt.rt_nr_running has not been updated yet when dequeue_top_rt_rq() is called so schedutil still considers that an RT task is running when the last task is dequeued. The update of rq->rt.rt_nr_running happens later in dequeue_rt_stack(). In fact, we can take advantage of the sequence that the dequeue then re-enqueue rt entities when a rt task is enqueued or dequeued; As a result enqueue_top_rt_rq() is always called when a task is enqueued or dequeued and also when groups are throttled or unthrottled. The only place that not use enqueue_top_rt_rq() is when root rt_rq is throttled. 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: efault@gmx.de Cc: juri.lelli@redhat.com Cc: patrick.bellasi@arm.com Cc: viresh.kumar@linaro.org Fixes: ('cpufreq/schedutil: Rewrite CPUFREQ_RT support') Link: http://lkml.kernel.org/r/1530021202-21695-1-git-send-email-vincent.guittot@linaro.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/cpufreq_schedutil.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -192,7 +192,7 @@ static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
		{
		struct rq *rq = cpu_rq(sg_cpu->cpu);

		if (rq->rt.rt_nr_running)
		if (rt_rq_is_runnable(&rq->rt))
		return sg_cpu->max;

		/*

kernel/sched/rt.c

+10 −6

Original line number	Diff line number	Diff line
		@@ -508,8 +508,11 @@ static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)

		rt_se = rt_rq->tg->rt_se[cpu];

		if (!rt_se)
		if (!rt_se) {
		dequeue_top_rt_rq(rt_rq);
		/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
		cpufreq_update_util(rq_of_rt_rq(rt_rq), 0);
		}
		else if (on_rt_rq(rt_se))
		dequeue_rt_entity(rt_se, 0);
		}
		@@ -1001,8 +1004,6 @@ dequeue_top_rt_rq(struct rt_rq *rt_rq)
		sub_nr_running(rq, rt_rq->rt_nr_running);
		rt_rq->rt_queued = 0;

		/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
		cpufreq_update_util(rq, 0);
		}

		static void
		@@ -1014,11 +1015,14 @@ enqueue_top_rt_rq(struct rt_rq *rt_rq)

		if (rt_rq->rt_queued)
		return;
		if (rt_rq_throttled(rt_rq) \|\| !rt_rq->rt_nr_running)

		if (rt_rq_throttled(rt_rq))
		return;

		if (rt_rq->rt_nr_running) {
		add_nr_running(rq, rt_rq->rt_nr_running);
		rt_rq->rt_queued = 1;
		}

		/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
		cpufreq_update_util(rq, 0);

kernel/sched/sched.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -609,6 +609,11 @@ struct rt_rq {
		#endif
		};

		static inline bool rt_rq_is_runnable(struct rt_rq *rt_rq)
		{
		return rt_rq->rt_queued && rt_rq->rt_nr_running;
		}

		/* Deadline class' related fields in a runqueue */
		struct dl_rq {
		/* runqueue is an rbtree, ordered by deadline */

Admin message