sched/rt: Fix picking RT and DL tasks from empty queue
The problems: 1) We check for rt_nr_running before call of put_prev_task(). If previous task is RT, its rt_rq may become throttled and dequeued after this call. In case of p is from rt->rq this just causes picking a task from throttled queue, but in case of its rt_rq is child we are guaranteed catch BUG_ON. 2) The same with deadline class. The only difference we operate on only dl_rq. This patch fixes all the above problems and it adds a small skip in the DL update like we've already done for RT class: if (unlikely((s64)delta_exec <= 0)) return; This will optimize sequential update_curr_dl() calls a little. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@gmail.com> Link: http://lkml.kernel.org/r/1393946746.3643.3.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
a02ed5e3e0
commit
734ff2a71f
|
@ -609,8 +609,8 @@ static void update_curr_dl(struct rq *rq)
|
|||
* approach need further study.
|
||||
*/
|
||||
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
|
||||
if (unlikely((s64)delta_exec < 0))
|
||||
delta_exec = 0;
|
||||
if (unlikely((s64)delta_exec <= 0))
|
||||
return;
|
||||
|
||||
schedstat_set(curr->se.statistics.exec_max,
|
||||
max(curr->se.statistics.exec_max, delta_exec));
|
||||
|
@ -1023,6 +1023,12 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)
|
|||
|
||||
if (need_pull_dl_task(rq, prev))
|
||||
pull_dl_task(rq);
|
||||
/*
|
||||
* When prev is DL, we may throttle it in put_prev_task().
|
||||
* So, we update time before we check for dl_nr_running.
|
||||
*/
|
||||
if (prev->sched_class == &dl_sched_class)
|
||||
update_curr_dl(rq);
|
||||
|
||||
if (unlikely(!dl_rq->dl_nr_running))
|
||||
return NULL;
|
||||
|
|
|
@ -1379,6 +1379,13 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
|
|||
return RETRY_TASK;
|
||||
}
|
||||
|
||||
/*
|
||||
* We may dequeue prev's rt_rq in put_prev_task().
|
||||
* So, we update time before rt_nr_running check.
|
||||
*/
|
||||
if (prev->sched_class == &rt_sched_class)
|
||||
update_curr_rt(rq);
|
||||
|
||||
if (!rt_rq->rt_nr_running)
|
||||
return NULL;
|
||||
|
||||
|
|
Loading…
Reference in a new issue