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Commit 8e717b19 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: schedule() speedup 



speed up schedule(): share the 'now' parameter that deactivate_task()
was calculating internally.

( this also fixes the small accounting window between the deactivate
  call and the pick_next_task() call. )

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7bfd0485

kernel/sched.c

+9 −10
Original line number Diff line number Diff line
@@ -940,10 +940,9 @@ static inline void activate_idle_task(struct task_struct *p, struct rq *rq) 
/*

 * deactivate_task - remove a task from the runqueue.

 */

static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)

static void

deactivate_task(struct rq *rq, struct task_struct *p, int sleep, u64 now)

{

	u64 now = rq_clock(rq);



	if (p->state == TASK_UNINTERRUPTIBLE)

		rq->nr_uninterruptible++;
@@ -2122,7 +2121,7 @@ void sched_exec(void) 
static void pull_task(struct rq *src_rq, struct task_struct *p,

		      struct rq *this_rq, int this_cpu)

{

	deactivate_task(src_rq, p, 0);

	deactivate_task(src_rq, p, 0, rq_clock(src_rq));

	set_task_cpu(p, this_cpu);

	activate_task(this_rq, p, 0);

	/*
@@ -3446,13 +3445,14 @@ asmlinkage void __sched schedule(void) 


	spin_lock_irq(&rq->lock);

	clear_tsk_need_resched(prev);

	now = __rq_clock(rq);



	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {

		if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&

				unlikely(signal_pending(prev)))) {

			prev->state = TASK_RUNNING;

		} else {

			deactivate_task(rq, prev, 1);

			deactivate_task(rq, prev, 1, now);

		}

		switch_count = &prev->nvcsw;

	}
@@ -3460,7 +3460,6 @@ asmlinkage void __sched schedule(void) 
	if (unlikely(!rq->nr_running))

		idle_balance(cpu, rq);



	now = __rq_clock(rq);

	prev->sched_class->put_prev_task(rq, prev, now);

	next = pick_next_task(rq, prev, now);
@@ -4220,7 +4219,7 @@ int sched_setscheduler(struct task_struct *p, int policy, 
	}

	on_rq = p->se.on_rq;

	if (on_rq)

		deactivate_task(rq, p, 0);

		deactivate_task(rq, p, 0, rq_clock(rq));

	oldprio = p->prio;

	__setscheduler(rq, p, policy, param->sched_priority);

	if (on_rq) {
@@ -4973,7 +4972,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 


	on_rq = p->se.on_rq;

	if (on_rq)

		deactivate_task(rq_src, p, 0);

		deactivate_task(rq_src, p, 0, rq_clock(rq_src));

	set_task_cpu(p, dest_cpu);

	if (on_rq) {

		activate_task(rq_dest, p, 0);
@@ -5387,7 +5386,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 
		rq->migration_thread = NULL;

		/* Idle task back to normal (off runqueue, low prio) */

		rq = task_rq_lock(rq->idle, &flags);

		deactivate_task(rq, rq->idle, 0);

		deactivate_task(rq, rq->idle, 0, rq_clock(rq));

		rq->idle->static_prio = MAX_PRIO;

		__setscheduler(rq, rq->idle, SCHED_NORMAL, 0);

		rq->idle->sched_class = &idle_sched_class;
@@ -6626,7 +6625,7 @@ void normalize_rt_tasks(void) 


		on_rq = p->se.on_rq;

		if (on_rq)

			deactivate_task(task_rq(p), p, 0);

			deactivate_task(task_rq(p), p, 0, rq_clock(task_rq(p)));

		__setscheduler(rq, p, SCHED_NORMAL, 0);

		if (on_rq) {

			activate_task(task_rq(p), p, 0);