Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing reprogramming

From	Frederic Weisbecker <fweisbec@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing reprogramming
Date	2017-06-03 14:50 +0200
Message-ID	<tOgFb-75a-1@gated-at.bofh.it> (permalink)
References	<tyHq2-6LU-35@gated-at.bofh.it> <tyHq3-6LU-37@gated-at.bofh.it> <tOcid-4wc-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Sat, Jun 03, 2017 at 08:06:41AM +0000, Levin, Alexander (Sasha Levin) wrote:
> On Fri, Apr 21, 2017 at 04:00:55PM +0200, Frederic Weisbecker wrote:
> > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> > index 502b320..be7ca4d 100644
> > --- a/kernel/time/tick-sched.c
> > +++ b/kernel/time/tick-sched.c
> > @@ -783,8 +783,13 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
> >  	tick = expires;
> >  
> >  	/* Skip reprogram of event if its not changed */
> > -	if (ts->tick_stopped && (expires == ts->next_tick))
> > -		goto out;
> > +	if (ts->tick_stopped && (expires == ts->next_tick)) {
> > +		/* Sanity check: make sure clockevent is actually programmed */
> > +		if (likely(dev->next_event <= ts->next_tick))
> > +			goto out;
> > +
> > +		WARN_ON_ONCE(1);
> > +	}
> 
> I seem to be hitting that in a KVM vm, even without load (sometimes
> right after boot):

Ah, can you tell me which tree you were using? Is it tip/master?
Can you give me its HEAD and your config file?

Thanks

Thread

Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing  reprogramming "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com> - 2017-06-03 10:10 +0200
  Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing  reprogramming Frederic Weisbecker <fweisbec@gmail.com> - 2017-06-03 14:50 +0200
    Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing  reprogramming Frederic Weisbecker <fweisbec@gmail.com> - 2017-06-06 17:00 +0200
      Re: [PATCH 2/2] tick: Make sure tick timer is active when bypassing  reprogramming Frederic Weisbecker <fweisbec@gmail.com> - 2017-06-07 16:20 +0200

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