Commit 5443a0be authored Dec 03, 2019 by Frederic Weisbecker Committed by Peter Zijlstra Dec 17, 2019

sched: Use fair:prio_changed() instead of ad-hoc implementation



set_user_nice() implements its own version of fair::prio_changed() and
therefore misses a specific optimization towards nohz_full CPUs that
avoid sending an resched IPI to a reniced task running alone. Use the
proper callback instead.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20191203160106.18806-3-frederic@kernel.org

parent 7c2e8bbd

kernel/sched/core.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -4540,17 +4540,17 @@ void set_user_nice(struct task_struct *p, long nice)
		p->prio = effective_prio(p);
		delta = p->prio - old_prio;

		if (queued) {
		if (queued)
		enqueue_task(rq, p, ENQUEUE_RESTORE \| ENQUEUE_NOCLOCK);
		if (running)
		set_next_task(rq, p);

		/*
		* If the task increased its priority or is running and
		* lowered its priority, then reschedule its CPU:
		*/
		if (delta < 0 \|\| (delta > 0 && task_running(rq, p)))
		resched_curr(rq);
		}
		if (running)
		set_next_task(rq, p);
		p->sched_class->prio_changed(rq, p, old_prio);

		out_unlock:
		task_rq_unlock(rq, p, &rf);
		}

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