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Commit ad2a3f13 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: rt-group: heirarchy aware throttle 



The bandwidth throttle code dequeues a group when it runs out of quota, and
re-queues it once the period rolls over and the quota gets refreshed.

Sadly it failed to take the hierarchy into consideration. Share more of the
enqueue/dequeue code with regular task opterations.

Also, some operations like sched_setscheduler() can dequeue/enqueue tasks that
are in throttled runqueues, we should not inadvertly re-enqueue empty runqueues
so check for that.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: default avatarDaniel K. <dk@uw.no>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7ea56616

kernel/sched_rt.c

+33 −26
Original line number Diff line number Diff line
@@ -449,13 +449,19 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) 
#endif

}



static void enqueue_rt_entity(struct sched_rt_entity *rt_se)

static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)

{

	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);

	struct rt_prio_array *array = &rt_rq->active;

	struct rt_rq *group_rq = group_rt_rq(rt_se);



	if (group_rq && rt_rq_throttled(group_rq))

	/*

	 * Don't enqueue the group if its throttled, or when empty.

	 * The latter is a consequence of the former when a child group

	 * get throttled and the current group doesn't have any other

	 * active members.

	 */

	if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))

		return;



	list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
@@ -464,7 +470,7 @@ static void enqueue_rt_entity(struct sched_rt_entity *rt_se) 
	inc_rt_tasks(rt_se, rt_rq);

}



static void dequeue_rt_entity(struct sched_rt_entity *rt_se)

static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)

{

	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);

	struct rt_prio_array *array = &rt_rq->active;
@@ -480,11 +486,10 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se) 
 * Because the prio of an upper entry depends on the lower

 * entries, we must remove entries top - down.

 */

static void dequeue_rt_stack(struct task_struct *p)

static void dequeue_rt_stack(struct sched_rt_entity *rt_se)

{

	struct sched_rt_entity *rt_se, *back = NULL;

	struct sched_rt_entity *back = NULL;



	rt_se = &p->rt;

	for_each_sched_rt_entity(rt_se) {

		rt_se->back = back;

		back = rt_se;
@@ -492,7 +497,26 @@ static void dequeue_rt_stack(struct task_struct *p) 


	for (rt_se = back; rt_se; rt_se = rt_se->back) {

		if (on_rt_rq(rt_se))

			dequeue_rt_entity(rt_se);

			__dequeue_rt_entity(rt_se);

	}

}



static void enqueue_rt_entity(struct sched_rt_entity *rt_se)

{

	dequeue_rt_stack(rt_se);

	for_each_sched_rt_entity(rt_se)

		__enqueue_rt_entity(rt_se);

}



static void dequeue_rt_entity(struct sched_rt_entity *rt_se)

{

	dequeue_rt_stack(rt_se);



	for_each_sched_rt_entity(rt_se) {

		struct rt_rq *rt_rq = group_rt_rq(rt_se);



		if (rt_rq && rt_rq->rt_nr_running)

			__enqueue_rt_entity(rt_se);

	}

}
@@ -506,32 +530,15 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) 
	if (wakeup)

		rt_se->timeout = 0;



	dequeue_rt_stack(p);



	/*

	 * enqueue everybody, bottom - up.

	 */

	for_each_sched_rt_entity(rt_se)

	enqueue_rt_entity(rt_se);

}



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

{

	struct sched_rt_entity *rt_se = &p->rt;

	struct rt_rq *rt_rq;



	update_curr_rt(rq);



	dequeue_rt_stack(p);



	/*

	 * re-enqueue all non-empty rt_rq entities.

	 */

	for_each_sched_rt_entity(rt_se) {

		rt_rq = group_rt_rq(rt_se);

		if (rt_rq && rt_rq->rt_nr_running)

			enqueue_rt_entity(rt_se);

	}

	dequeue_rt_entity(rt_se);

}



/*