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Commit 4fd29176 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

sched: add rt-overload tracking 



This patch adds an RT overload accounting system. When a runqueue has
more than one RT task queued, it is marked as overloaded. That is that it
is a candidate to have RT tasks pulled from it.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e8fa1362

kernel/sched_rt.c

+36 −0
Original line number Diff line number Diff line
@@ -3,6 +3,38 @@ 
 * policies)

 */



#ifdef CONFIG_SMP

static cpumask_t rt_overload_mask;

static atomic_t rto_count;

static inline int rt_overloaded(void)

{

	return atomic_read(&rto_count);

}

static inline cpumask_t *rt_overload(void)

{

	return &rt_overload_mask;

}

static inline void rt_set_overload(struct rq *rq)

{

	cpu_set(rq->cpu, rt_overload_mask);

	/*

	 * Make sure the mask is visible before we set

	 * the overload count. That is checked to determine

	 * if we should look at the mask. It would be a shame

	 * if we looked at the mask, but the mask was not

	 * updated yet.

	 */

	wmb();

	atomic_inc(&rto_count);

}

static inline void rt_clear_overload(struct rq *rq)

{

	/* the order here really doesn't matter */

	atomic_dec(&rto_count);

	cpu_clear(rq->cpu, rt_overload_mask);

}

#endif /* CONFIG_SMP */



/*

 * Update the current task's runtime statistics. Skip current tasks that

 * are not in our scheduling class.
@@ -33,6 +65,8 @@ static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq) 
#ifdef CONFIG_SMP

	if (p->prio < rq->rt.highest_prio)

		rq->rt.highest_prio = p->prio;

	if (rq->rt.rt_nr_running > 1)

		rt_set_overload(rq);

#endif /* CONFIG_SMP */

}
@@ -54,6 +88,8 @@ static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq) 
		} /* otherwise leave rq->highest prio alone */

	} else

		rq->rt.highest_prio = MAX_RT_PRIO;

	if (rq->rt.rt_nr_running < 2)

		rt_clear_overload(rq);

#endif /* CONFIG_SMP */

}