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Commit 00bf7bfc authored Oct 15, 2007 by Ingo Molnar

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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

parent 0702e3eb

kernel/sched.c

+1 −4

Original line number	Original line	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;		unsigned long flags;
	struct rq *rq;		struct rq *rq;
	int this_cpu;

	rq = task_rq_lock(p, &flags);		rq = task_rq_lock(p, &flags);
	BUG_ON(p->state != TASK_RUNNING);		BUG_ON(p->state != TASK_RUNNING);
	this_cpu = smp_processor_id(); /* parent's CPU */
	update_rq_clock(rq);		update_rq_clock(rq);

	p->prio = effective_prio(p);		p->prio = effective_prio(p);

	if (task_cpu(p) != this_cpu \|\| !p->sched_class->task_new \|\|		if (!p->sched_class->task_new \|\| !current->se.on_rq \|\| !rq->cfs.curr) {
	!current->se.on_rq) {
	activate_task(rq, p, 0);		activate_task(rq, p, 0);
	} else {		} else {
	/*		/*

kernel/sched_fair.c

+2 −1

Original line number	Original line	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 cfs_rq *cfs_rq = task_cfs_rq(p);
	struct sched_entity se = &p->se, curr = cfs_rq->curr;		struct sched_entity se = &p->se, curr = cfs_rq->curr;
			int this_cpu = smp_processor_id();

	sched_info_queued(p);		sched_info_queued(p);

	update_curr(cfs_rq);		update_curr(cfs_rq);
	place_entity(cfs_rq, se, 1);		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) {		curr->vruntime < se->vruntime) {
	/*		/*
	* Upon rescheduling, sched_class::put_prev_task() will place		* Upon rescheduling, sched_class::put_prev_task() will place