Commit 326587b8 authored Jan 25, 2008 by Dmitry Adamushko Committed by Ingo Molnar Jan 25, 2008

sched: fix goto retry in pick_next_task_rt()



looking at it one more time:

(1) it looks to me that there is no need to call
sched_rt_ratio_exceeded() from pick_next_rt_entity()

- [ for CONFIG_FAIR_GROUP_SCHED ] queues with rt_rq->rt_throttled are
not within this 'tree-like hierarchy' (or whatever we should call it
:-)

- there is also no need to re-check 'rt_rq->rt_time > ratio' at this
point as 'rt_rq->rt_time' couldn't have been increased since the last
call to update_curr_rt() (which obviously calls
sched_rt_ratio_esceeded())
well, it might be that 'ratio' for this rt_rq has been re-configured
(and the period over which this rt_rq was active has not yet been
finished)... but I don't think we should really take this into
account.

(2) now pick_next_rt_entity() must never return NULL, so let's change
pick_next_task_rt() accordingly.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent e118adef

kernel/sched_rt.c

+2 −7

Original line number	Diff line number	Diff line
		@@ -476,15 +476,12 @@ static struct sched_rt_entity pick_next_rt_entity(struct rq rq,
		struct list_head *queue;
		int idx;

		if (sched_rt_ratio_exceeded(rt_rq))
		goto out;

		idx = sched_find_first_bit(array->bitmap);
		BUG_ON(idx >= MAX_RT_PRIO);

		queue = array->queue + idx;
		next = list_entry(queue->next, struct sched_rt_entity, run_list);
		out:

		return next;
		}

		@@ -494,7 +491,6 @@ static struct task_struct pick_next_task_rt(struct rq rq)
		struct task_struct *p;
		struct rt_rq *rt_rq;

		retry:
		rt_rq = &rq->rt;

		if (unlikely(!rt_rq->rt_nr_running))
		@@ -505,8 +501,7 @@ static struct task_struct pick_next_task_rt(struct rq rq)

		do {
		rt_se = pick_next_rt_entity(rq, rt_rq);
		if (unlikely(!rt_se))
		goto retry;
		BUG_ON(!rt_se);
		rt_rq = group_rt_rq(rt_se);
		} while (rt_rq);