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Commit bce4dc80 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Simplify update_rq_clock() in __schedule() 



Instead of relying on deactivate_task() to call update_rq_clock() and
handling the case where it didn't happen (task_on_rq_queued),
unconditionally do update_rq_clock() and skip any further updates.

This also avoids a double update on deactivate_task() + ttwu_local().

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 77558e4d

kernel/sched/core.c

+3 −5
Original line number Diff line number Diff line
@@ -2114,7 +2114,7 @@ static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf) 
			delayacct_blkio_end();

			atomic_dec(&rq->nr_iowait);

		}

		ttwu_activate(rq, p, ENQUEUE_WAKEUP);

		ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK);

	}



	ttwu_do_wakeup(rq, p, 0, rf);
@@ -3393,13 +3393,14 @@ static void __sched notrace __schedule(bool preempt) 


	/* Promote REQ to ACT */

	rq->clock_update_flags <<= 1;

	update_rq_clock(rq);



	switch_count = &prev->nivcsw;

	if (!preempt && prev->state) {

		if (unlikely(signal_pending_state(prev->state, prev))) {

			prev->state = TASK_RUNNING;

		} else {

			deactivate_task(rq, prev, DEQUEUE_SLEEP);

			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);

			prev->on_rq = 0;



			if (prev->in_iowait) {
@@ -3423,9 +3424,6 @@ static void __sched notrace __schedule(bool preempt) 
		switch_count = &prev->nvcsw;

	}



	if (task_on_rq_queued(prev))

		update_rq_clock(rq);



	next = pick_next_task(rq, prev, &rf);

	clear_tsk_need_resched(prev);

	clear_preempt_need_resched();