From: Frederic Weisbecker <fweisbec@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
James Hartsock <hartsjc@redhat.com>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] nohz: Fix collision between tick and other hrtimers
Date: Mon, 26 Dec 2016 17:40:19 +0100 [thread overview]
Message-ID: <20161226164015.GA2375@lerouge> (raw)
In-Reply-To: <1482721017.11006.83.camel@redhat.com>
On Sun, Dec 25, 2016 at 09:56:57PM -0500, Rik van Riel wrote:
> On Sat, 2016-12-24 at 17:15 +0100, Frederic Weisbecker wrote:
> > When the tick is stopped and an interrupt occurs afterward, we check
> > on
> > that interrupt exit if the next tick needs to be rescheduled. If it
> > doesn't need any update, we don't want to do anything.
> >
> > In order to check if the tick needs an update, we compare it against
> > the
> > clockevent device deadline. Now that's a problem because the
> > clockevent
> > device is at a lower level than the tick itself if it is implemented
> > on top of hrtimer.
>
> Ohhhhh, good find. That is one subtle bug.
Oh yeah, it took me several month to debug that one :-) !
>
> Acked-by: Rik van Riel <riel@redhat.com>
Thanks!
>
> --
> All Rights Reversed.
next prev parent reply other threads:[~2016-12-26 16:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-24 16:15 [PATCH] nohz: Fix collision between tick and other hrtimers Frederic Weisbecker
2016-12-26 2:56 ` Rik van Riel
2016-12-26 16:40 ` Frederic Weisbecker [this message]
2016-12-26 23:44 ` Wanpeng Li
2016-12-29 16:42 ` Thomas Gleixner
2016-12-29 16:53 ` Frederic Weisbecker
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