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Commit 606dba2e authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Push put_prev_task() into pick_next_task() 



In order to avoid having to do put/set on a whole cgroup hierarchy
when we context switch, push the put into pick_next_task() so that
both operations are in the same function. Further changes then allow
us to possibly optimize away redundant work.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent fed14d45

kernel/sched/core.c

+8 −13
Original line number Diff line number Diff line
@@ -2579,18 +2579,11 @@ static inline void schedule_debug(struct task_struct *prev) 
	schedstat_inc(this_rq(), sched_count);

}



static void put_prev_task(struct rq *rq, struct task_struct *prev)

{

	if (prev->on_rq || rq->skip_clock_update < 0)

		update_rq_clock(rq);

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

}



/*

 * Pick up the highest-prio task:

 */

static inline struct task_struct *

pick_next_task(struct rq *rq)

pick_next_task(struct rq *rq, struct task_struct *prev)

{

	const struct sched_class *class;

	struct task_struct *p;
@@ -2600,13 +2593,13 @@ pick_next_task(struct rq *rq) 
	 * the fair class we can call that function directly:

	 */

	if (likely(rq->nr_running == rq->cfs.h_nr_running)) {

		p = fair_sched_class.pick_next_task(rq);

		p = fair_sched_class.pick_next_task(rq, prev);

		if (likely(p))

			return p;

	}



	for_each_class(class) {

		p = class->pick_next_task(rq);

		p = class->pick_next_task(rq, prev);

		if (p)

			return p;

	}
@@ -2714,8 +2707,10 @@ static void __sched __schedule(void) 
			rq->idle_stamp = 0;

	}



	put_prev_task(rq, prev);

	next = pick_next_task(rq);

	if (prev->on_rq || rq->skip_clock_update < 0)

		update_rq_clock(rq);



	next = pick_next_task(rq, prev);

	clear_tsk_need_resched(prev);

	clear_preempt_need_resched();

	rq->skip_clock_update = 0;
@@ -4748,7 +4743,7 @@ static void migrate_tasks(unsigned int dead_cpu) 
		if (rq->nr_running == 1)

			break;



		next = pick_next_task(rq);

		next = pick_next_task(rq, NULL);

		BUG_ON(!next);

		next->sched_class->put_prev_task(rq, next);

kernel/sched/deadline.c

+4 −1
Original line number Diff line number Diff line
@@ -990,7 +990,7 @@ static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, 
	return rb_entry(left, struct sched_dl_entity, rb_node);

}



struct task_struct *pick_next_task_dl(struct rq *rq)

struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)

{

	struct sched_dl_entity *dl_se;

	struct task_struct *p;
@@ -1001,6 +1001,9 @@ struct task_struct *pick_next_task_dl(struct rq *rq) 
	if (unlikely(!dl_rq->dl_nr_running))

		return NULL;



	if (prev)

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



	dl_se = pick_next_dl_entity(rq, dl_rq);

	BUG_ON(!dl_se);

kernel/sched/fair.c

+5 −1
Original line number Diff line number Diff line
@@ -4655,7 +4655,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ 
		set_last_buddy(se);

}



static struct task_struct *pick_next_task_fair(struct rq *rq)

static struct task_struct *

pick_next_task_fair(struct rq *rq, struct task_struct *prev)

{

	struct task_struct *p;

	struct cfs_rq *cfs_rq = &rq->cfs;
@@ -4664,6 +4665,9 @@ static struct task_struct *pick_next_task_fair(struct rq *rq) 
	if (!cfs_rq->nr_running)

		return NULL;



	if (prev)

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



	do {

		se = pick_next_entity(cfs_rq);

		set_next_entity(cfs_rq, se);

kernel/sched/idle_task.c

+5 −1
Original line number Diff line number Diff line
@@ -33,8 +33,12 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl 
	resched_task(rq->idle);

}



static struct task_struct *pick_next_task_idle(struct rq *rq)

static struct task_struct *

pick_next_task_idle(struct rq *rq, struct task_struct *prev)

{

	if (prev)

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



	schedstat_inc(rq, sched_goidle);

#ifdef CONFIG_SMP

	/* Trigger the post schedule to do an idle_enter for CFS */

kernel/sched/rt.c

+16 −11
Original line number Diff line number Diff line
@@ -1310,15 +1310,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) 
{

	struct sched_rt_entity *rt_se;

	struct task_struct *p;

	struct rt_rq *rt_rq;



	rt_rq = &rq->rt;



	if (!rt_rq->rt_nr_running)

		return NULL;



	if (rt_rq_throttled(rt_rq))

		return NULL;

	struct rt_rq *rt_rq  = &rq->rt;



	do {

		rt_se = pick_next_rt_entity(rq, rt_rq);
@@ -1332,9 +1324,22 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) 
	return p;

}



static struct task_struct *pick_next_task_rt(struct rq *rq)

static struct task_struct *

pick_next_task_rt(struct rq *rq, struct task_struct *prev)

{

	struct task_struct *p = _pick_next_task_rt(rq);

	struct task_struct *p;

	struct rt_rq *rt_rq = &rq->rt;



	if (!rt_rq->rt_nr_running)

		return NULL;



	if (rt_rq_throttled(rt_rq))

		return NULL;



	if (prev)

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



	p = _pick_next_task_rt(rq);



	/* The running task is never eligible for pushing */

	if (p)