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Commit 00bf7bfc authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: fix: move the CPU check into ->task_new_fair() 



noticed by Peter Zijlstra:

fix: move the CPU check into ->task_new_fair(), this way we
can call place_entity() and get child ->vruntime right at
initial wakeup time.

(without this there can be large latencies)

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
parent 0702e3eb

kernel/sched.c

+1 −4
Original line number Diff line number Diff line
@@ -1660,17 +1660,14 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) 
{

	unsigned long flags;

	struct rq *rq;

	int this_cpu;



	rq = task_rq_lock(p, &flags);

	BUG_ON(p->state != TASK_RUNNING);

	this_cpu = smp_processor_id(); /* parent's CPU */

	update_rq_clock(rq);



	p->prio = effective_prio(p);



	if (task_cpu(p) != this_cpu || !p->sched_class->task_new ||

							!current->se.on_rq) {

	if (!p->sched_class->task_new || !current->se.on_rq || !rq->cfs.curr) {

		activate_task(rq, p, 0);

	} else {

		/*

kernel/sched_fair.c

+2 −1
Original line number Diff line number Diff line
@@ -1007,13 +1007,14 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) 
{

	struct cfs_rq *cfs_rq = task_cfs_rq(p);

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

	int this_cpu = smp_processor_id();



	sched_info_queued(p);



	update_curr(cfs_rq);

	place_entity(cfs_rq, se, 1);



	if (sysctl_sched_child_runs_first &&

	if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&

			curr->vruntime < se->vruntime) {

		/*

		 * Upon rescheduling, sched_class::put_prev_task() will place