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Commit 03e89e45 authored by Mike Galbraith's avatar Mike Galbraith Committed by Ingo Molnar
Browse files

sched: fix wakeup preemption clock 



Impact: sharpen the wakeup-granularity to always be against current scheduler time

It was possible to do the preemption check against an old time stamp.

Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d65bd5ec

kernel/sched.c

+1 −1
Original line number Diff line number Diff line
@@ -2266,6 +2266,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 


	smp_wmb();

	rq = task_rq_lock(p, &flags);

	update_rq_clock(rq);

	old_state = p->state;

	if (!(old_state & state))

		goto out;
@@ -2323,7 +2324,6 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
		schedstat_inc(p, se.nr_wakeups_local);

	else

		schedstat_inc(p, se.nr_wakeups_remote);

	update_rq_clock(rq);

	activate_task(rq, p, 1);

	success = 1;

kernel/sched_fair.c

+3 −4
Original line number Diff line number Diff line
@@ -1345,12 +1345,11 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync) 
{

	struct task_struct *curr = rq->curr;

	struct sched_entity *se = &curr->se, *pse = &p->se;



	if (unlikely(rt_prio(p->prio))) {

	struct cfs_rq *cfs_rq = task_cfs_rq(curr);



		update_rq_clock(rq);

	update_curr(cfs_rq);



	if (unlikely(rt_prio(p->prio))) {

		resched_task(curr);

		return;

	}