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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: Peter 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: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Peter Zijlstra 2017-02-21 14:36:23 +01:00 committed by Ingo Molnar
parent 7134b3e941
commit 77558e4d01
1 changed files with 3 additions and 1 deletions
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4
kernel/sched/core.c
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@ -1685,7 +1685,7 @@ static void
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
struct rq_flags *rf)
{
int en_flags = ENQUEUE_WAKEUP;
int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
lockdep_assert_held(&rq->lock);
@ -1737,6 +1737,7 @@ void sched_ttwu_pending(void)
return;
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
while (llist) {
int wake_flags = 0;
@ -1849,6 +1850,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
#endif
rq_lock(rq, &rf);
update_rq_clock(rq);
ttwu_do_activate(rq, p, wake_flags, &rf);
rq_unlock(rq, &rf);
}