Commit 77558e4d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Make sched_ttwu_pending() atomic in time 



Since all tasks on the wake_list are woken under a single rq->lock
avoid calling update_rq_clock() for each task.

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 7134b3e9

kernel/sched/core.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -1685,7 +1685,7 @@ static void 
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,

ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,

		 struct rq_flags *rf)

		 struct rq_flags *rf)

{

{

	int en_flags = ENQUEUE_WAKEUP;

	int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;





	lockdep_assert_held(&rq->lock);

	lockdep_assert_held(&rq->lock);
@@ -1737,6 +1737,7 @@ void sched_ttwu_pending(void) 
		return;

		return;





	rq_lock_irqsave(rq, &rf);

	rq_lock_irqsave(rq, &rf);

	update_rq_clock(rq);





	while (llist) {

	while (llist) {

		int wake_flags = 0;

		int wake_flags = 0;
@@ -1849,6 +1850,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) 
#endif

#endif





	rq_lock(rq, &rf);

	rq_lock(rq, &rf);

	update_rq_clock(rq);

	ttwu_do_activate(rq, p, wake_flags, &rf);

	ttwu_do_activate(rq, p, wake_flags, &rf);

	rq_unlock(rq, &rf);

	rq_unlock(rq, &rf);

}

}