Re: [BUGFIX][PATCH] Fix sched rt group scheduling when hierachy is enabled
From: Balbir Singh
Date: Fri Mar 04 2011 - 03:59:28 EST
>>> deactivate_task(b); /* A.throttled == 1 && A.rt_nr_running == 0 */
>>> do_sched_rt_period_timer(); /* A.run_time == 0 && A.throttled == 0*/
>>
>> Note at some point rt_time becomes 0 and if enqueue is not set, the
>
> If the group should be add back, it will be at the first
> do_sched_rt_period_timer() which decreases run_time;
>
As long as idle is 0, the period will continue to run, if it has
rt_nr_running or rt_time, the timer will run.
>> next do_sched_rt_period_timer() is a NOP and does not enqueue back the
>> group
>
> Otherwise it will be added back when a task is attching to it.
>
> I still can't see how a unthrottled group which has task attched stay
> unqueued.
The other way of looking at the first change is
Can we have rt_time as 0, rt_nr_running >=1, rt_throttled !=0 and
still not have the rt_rq enqueued?
If this is not the case, we don't lose much, a quick check for
rt_nr_running and on_rt_q
Balbir
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