Commit 764a9d6f authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

sched: track highest prio task queued 



This patch adds accounting to each runqueue to keep track of the
highest prio task queued on the run queue. We only care about
RT tasks, so if the run queue does not contain any active RT tasks
its priority will be considered MAX_RT_PRIO.

This information will be used for later patches.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 63489e45

kernel/sched.c

+3 −0
Original line number Diff line number Diff line
@@ -343,6 +343,8 @@ struct rt_rq { 
	int rt_load_balance_idx;

	struct list_head *rt_load_balance_head, *rt_load_balance_curr;

	unsigned long rt_nr_running;

	/* highest queued rt task prio */

	int highest_prio;

};



/*
@@ -6864,6 +6866,7 @@ void __init sched_init(void) 
		rq->cpu = i;

		rq->migration_thread = NULL;

		INIT_LIST_HEAD(&rq->migration_queue);

		rq->rt.highest_prio = MAX_RT_PRIO;

#endif

		atomic_set(&rq->nr_iowait, 0);

kernel/sched_rt.c

+18 −0
Original line number Diff line number Diff line
@@ -30,6 +30,10 @@ static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq) 
{

	WARN_ON(!rt_task(p));

	rq->rt.rt_nr_running++;

#ifdef CONFIG_SMP

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

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

#endif /* CONFIG_SMP */

}



static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq)
@@ -37,6 +41,20 @@ static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq) 
	WARN_ON(!rt_task(p));

	WARN_ON(!rq->rt.rt_nr_running);

	rq->rt.rt_nr_running--;

#ifdef CONFIG_SMP

	if (rq->rt.rt_nr_running) {

		struct rt_prio_array *array;



		WARN_ON(p->prio < rq->rt.highest_prio);

		if (p->prio == rq->rt.highest_prio) {

			/* recalculate */

			array = &rq->rt.active;

			rq->rt.highest_prio =

				sched_find_first_bit(array->bitmap);

		} /* otherwise leave rq->highest prio alone */

	} else

		rq->rt.highest_prio = MAX_RT_PRIO;

#endif /* CONFIG_SMP */

}



static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)

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