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SubjectRe: [RFC 0/12][PATCH] SCHED_DEADLINE: fork and terminate task logic
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On Wed, 2010-01-13 at 17:15 +0100, Peter Zijlstra wrote:
> On Wed, 2010-01-13 at 12:11 +0100, Raistlin wrote:
>
> > > > + } else if (rt_prio(p->prio))
> > > > + p->sched_class = &rt_sched_class;
> > > > + else
> > > > p->sched_class = &fair_sched_class;
> > > >
> > > > #ifdef CONFIG_SMP
> > > > @@ -2744,6 +2756,10 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
> > > > if (mm)
> > > > mmdrop(mm);
> > > > if (unlikely(prev_state == TASK_DEAD)) {
> > > > + /* a deadline task is dying: stop the bandwidth timer */
> > > > + if (deadline_task(prev))
> > > > + hrtimer_cancel(&prev->dl.dl_timer);
> > > > +
> > > > /*
> > > > * Remove function-return probe instances associated with this
> > > > * task and put them back on the free list.
> > >
> > > Shouldn't this be done in the ->dequeue_task() callback?
> > >
> > Not sure of this snippet... Actually, it is one of the most disturbing
> > piece of code of this whole scheduler. :-(
> >
> > The reason why it is here is that I think it is needed to call
> > hrtimer_cancel() _without_ holding the rq->lock, is that correct?
>
> I think we can nest the hrtimer base lock inside the rq->lock these
> days, so it should be safe to call while holding it, anyway, lockdep
> will quickly tell you if you try ;-)
>
Nice, I'll try this soon, thanks.

> > It is
>
> Is that a stmt or an unfinished sentence?
>
No, this is nothing, sorry! :-P

Regards,
Dario


--
<<This happens because I choose it to happen!>> (Raistlin Majere)
----------------------------------------------------------------------
Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa (Italy)

http://blog.linux.it/raistlin / raistlin@ekiga.net /
dario.faggioli@jabber.org
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