Re: [PATCH 10/10] sched: rt: dont stop the period timer when thereare tasks wanting to run

From: Peter Zijlstra
Date: Thu Jun 19 2008 - 16:17:00 EST


On Thu, 2008-06-19 at 20:10 +0000, Daniel K. wrote:
> Peter Zijlstra wrote:
> > When a runnable group failed to get any runtime within a period it would be
> > found idle and the period timer would be stopped.
> >
> > So if the group ever gets throttled, it will never wake up again.
> >
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> > Reported-by: "Daniel K." <dk@xxxxx>
> Tested-by: Daniel K. <dk@xxxxx>
>
> I think this should go into .26 as well, due to the non-intuitiveness
> of the knobs that cause this if they are fiddled with in the wrong way.

Sounds reasonable, Ingo?

> > ---
> > kernel/sched_rt.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > Index: linux-2.6/kernel/sched_rt.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/sched_rt.c
> > +++ linux-2.6/kernel/sched_rt.c
> > @@ -408,7 +408,8 @@ static int do_sched_rt_period_timer(stru
> > if (rt_rq->rt_time || rt_rq->rt_nr_running)
> > idle = 0;
> > spin_unlock(&rt_rq->rt_runtime_lock);
> > - }
> > + } else if (rt_rq->rt_nr_running)
> > + idle = 0;
> >
> > if (enqueue)
> > sched_rt_rq_enqueue(rt_rq);
> >
>

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