Commit 8046d680 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

sched,rt: Remove return value from pull_rt_task() 



In order to be able to use pull_rt_task() from a callback, we need to
do away with the return value.

Since the return value indicates if we should reschedule, do this
inside the function. Since not all callers currently do this, this can
increase the number of reschedules due rt balancing.

Too many reschedules is not a correctness issues, too few are.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124742.679002000@infradead.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4c9a4bc8

kernel/sched/rt.c

+11 −11
Original line number Original line Diff line number Diff line
@@ -260,7 +260,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) 




#ifdef CONFIG_SMP

#ifdef CONFIG_SMP





static int pull_rt_task(struct rq *this_rq);

static void pull_rt_task(struct rq *this_rq);





static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)

static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)

{

{
@@ -415,9 +415,8 @@ static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) 
	return false;

	return false;

}

}





static inline int pull_rt_task(struct rq *this_rq)

static inline void pull_rt_task(struct rq *this_rq)

{

{

	return 0;

}

}





static inline void queue_push_tasks(struct rq *rq)

static inline void queue_push_tasks(struct rq *rq)
@@ -1955,14 +1954,15 @@ static void push_irq_work_func(struct irq_work *work) 
}

}

#endif /* HAVE_RT_PUSH_IPI */

#endif /* HAVE_RT_PUSH_IPI */





static int pull_rt_task(struct rq *this_rq)

static void pull_rt_task(struct rq *this_rq)

{

{

	int this_cpu = this_rq->cpu, ret = 0, cpu;

	int this_cpu = this_rq->cpu, cpu;

	bool resched = false;

	struct task_struct *p;

	struct task_struct *p;

	struct rq *src_rq;

	struct rq *src_rq;





	if (likely(!rt_overloaded(this_rq)))

	if (likely(!rt_overloaded(this_rq)))

		return 0;

		return;





	/*

	/*

	 * Match the barrier from rt_set_overloaded; this guarantees that if we

	 * Match the barrier from rt_set_overloaded; this guarantees that if we
@@ -1973,7 +1973,7 @@ static int pull_rt_task(struct rq *this_rq) 
#ifdef HAVE_RT_PUSH_IPI

#ifdef HAVE_RT_PUSH_IPI

	if (sched_feat(RT_PUSH_IPI)) {

	if (sched_feat(RT_PUSH_IPI)) {

		tell_cpu_to_push(this_rq);

		tell_cpu_to_push(this_rq);

		return 0;

		return;

	}

	}

#endif

#endif
@@ -2026,7 +2026,7 @@ static int pull_rt_task(struct rq *this_rq) 
			if (p->prio < src_rq->curr->prio)

			if (p->prio < src_rq->curr->prio)

				goto skip;

				goto skip;





			ret = 1;

			resched = true;





			deactivate_task(src_rq, p, 0);

			deactivate_task(src_rq, p, 0);

			set_task_cpu(p, this_cpu);

			set_task_cpu(p, this_cpu);
@@ -2042,7 +2042,8 @@ skip: 
		double_unlock_balance(this_rq, src_rq);

		double_unlock_balance(this_rq, src_rq);

	}

	}





	return ret;

	if (resched)

		resched_curr(this_rq);

}

}





/*

/*
@@ -2138,8 +2139,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p) 
	if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)

	if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)

		return;

		return;





	if (pull_rt_task(rq))

	pull_rt_task(rq);

		resched_curr(rq);

}

}





void __init init_sched_rt_class(void)

void __init init_sched_rt_class(void)

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