Messages in this thread | | | Date | Tue, 5 Apr 2016 19:05:11 +0200 | From | luca abeni <> | Subject | Re: [RFC v2 3/7] Improve the tracking of active utilisation |
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Hi Peter,
On Tue, 5 Apr 2016 14:42:42 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, Apr 01, 2016 at 05:12:29PM +0200, Luca Abeni wrote: > > @@ -526,7 +575,18 @@ static void update_dl_entity(struct sched_dl_entity *dl_se, > > struct dl_rq *dl_rq = dl_rq_of_se(dl_se); > > struct rq *rq = rq_of_dl_rq(dl_rq); > > > > - add_running_bw(dl_se, dl_rq); > > + /* > > + * If the "inactive timer" is still active, stop it and leave > > + * the active utilisation unchanged. > > + * Otherwise, increase the active utilisation. > > + * If the timer cannot be cancelled, inactive_task_timer() will > > + * find the task state as TASK_RUNNING, and will do nothing, so > > + * we are still safe. > > + */ > > + if (hrtimer_active(&dl_se->inactive_timer)) > > + hrtimer_try_to_cancel(&dl_se->inactive_timer); > > _try_, what happens if that fails?
I think inactive_task_timer() will run, but will see p->state == TASK_RUNNING and will return immediately.
I think I have actually seen this happening during my tests, because adding the "if (p->state == TASK_RUNNING)" in inactive_task_timer() fixed some issues that I was seeing.
Thanks, Luca
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