lkml.org 
[lkml]   [2011]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [BUGFIX][PATCH] Fix sched rt group scheduling when hierachy is enabled
* Yong Zhang <yong.zhang0@gmail.com> [2011-03-04 11:43:16]:

> On Thu, Mar 3, 2011 at 11:29 PM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > No, not really :) It is required, it is a backup check to see if we
> > have queued tasks, rt_time of 0 and the runqueue is not throttled, why
> > should it be dequeued?
>
> But I can't see where that kind of rt_rq is dequeued, mind pointing it out?
>

So here is what I saw

1. sched_dequeue_stack called from the dequeue path dequeues the
queues and sets rt_nr_running to 0
2. Enqueuing fails because rt_throttled is set for the group_rq
(parent who is throttled)
3. This causes further enqueue to fail, since rt_nr_running did
not increment in step 2, eventually the timer decrements rt_time
to 0 and the task is never picked up.

--
Three Cheers,
Balbir


\
 
 \ /
  Last update: 2011-03-04 08:43    [from the cache]
©2003-2011 Jasper Spaans