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sched: track highest prio task queued

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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: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-01-25 21:08:04 +01:00 committed by Ingo Molnar
parent 63489e45e2
commit 764a9d6fe4
2 changed files with 21 additions and 0 deletions
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3
kernel/sched.c
View File

@ -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);

18
kernel/sched_rt.c
View File

@ -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)