From: Marc.Zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM
Date: Fri, 27 May 2011 16:29:25 +0100 [thread overview]
Message-ID: <1306510165.27474.272.camel@e102391-lin.cambridge.arm.com> (raw)
In-Reply-To: <4DDFC1D6.4010303@ti.com>
On Fri, 2011-05-27 at 20:53 +0530, Santosh Shilimkar wrote:
> Peter,
>
> On 5/26/2011 10:53 PM, Peter Zijlstra wrote:
> > On Thu, 2011-05-26 at 19:17 +0200, Peter Zijlstra wrote:
> >> On Thu, 2011-05-26 at 19:04 +0200, Oleg Nesterov wrote:
> >>> On 05/26, Peter Zijlstra wrote:
> >>>>
> >>>> @@ -2636,7 +2636,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
> >>>> * to spin on ->on_cpu if p is current, since that would
> >>>> * deadlock.
> >>>> */
> >>>> - if (p == current) {
> >>>> + if (cpu == smp_processor_id()) {
> >>>> + p->sched_contributes_to_load = 0;
> >>>> ttwu_queue(p, cpu);
> >>>
> >>> Btw. I do not pretend I really understand se->vruntime, but in this
> >>> case we are doing enqueue_task() without ->task_waking(), however we
> >>> pass ENQUEUE_WAKING. Is it correct?
> >>
> >> No its not, that's the thing that I got wrong the first time and caused
> >> these pauses.
> >
> > We'd end up with something like the below, which isn't too different
> > from what I've now got queued.
> >
> > It has the extra cpu == smp_processor_id() check, but I'm not sure this
> > whole case is worth the trouble. I could go stick some counters in to
> > verify how often all this happens I guess.
> >
> Are you planning send version of this patch for stable .39
> too ?
.39 is fine, as the ttwu() changes only appeared in mainline during the
current merge window.
Cheers,
M.
--
Reality is an implementation detail.
next prev parent reply other threads:[~2011-05-27 15:29 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-24 18:13 [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM Marc Zyngier
2011-05-24 21:32 ` Peter Zijlstra
2011-05-24 21:39 ` Ingo Molnar
2011-05-25 12:23 ` Marc Zyngier
2011-05-25 17:08 ` Peter Zijlstra
2011-05-25 21:15 ` Peter Zijlstra
2011-05-26 7:29 ` Yong Zhang
2011-05-26 10:32 ` Peter Zijlstra
2011-05-26 11:02 ` Marc Zyngier
2011-05-26 11:32 ` Peter Zijlstra
2011-05-26 12:21 ` Peter Zijlstra
2011-05-26 12:26 ` Ingo Molnar
2011-05-26 12:31 ` Russell King - ARM Linux
2011-05-26 12:37 ` Peter Zijlstra
2011-05-26 12:50 ` Ingo Molnar
2011-05-26 13:36 ` Russell King - ARM Linux
2011-05-26 14:45 ` Catalin Marinas
2011-05-27 12:06 ` Ingo Molnar
2011-05-27 17:55 ` Russell King - ARM Linux
2011-05-27 19:41 ` Nicolas Pitre
2011-05-27 20:52 ` Russell King - ARM Linux
2011-05-28 13:13 ` Peter Zijlstra
2011-05-31 11:08 ` Michal Simek
2011-05-31 13:22 ` Peter Zijlstra
2011-05-31 13:37 ` Michal Simek
2011-05-31 13:52 ` Peter Zijlstra
2011-05-31 14:08 ` Michal Simek
2011-05-31 14:29 ` Peter Zijlstra
2011-05-29 10:21 ` Catalin Marinas
2011-05-29 10:26 ` Russell King - ARM Linux
2011-05-29 12:01 ` Catalin Marinas
2011-05-29 13:19 ` Russell King - ARM Linux
2011-05-29 21:21 ` Catalin Marinas
2011-05-29 9:51 ` Catalin Marinas
2011-06-06 10:29 ` Pavel Machek
2011-05-26 14:56 ` Marc Zyngier
2011-05-26 15:45 ` Oleg Nesterov
2011-05-26 15:59 ` Peter Zijlstra
2011-05-26 16:09 ` Peter Zijlstra
2011-05-26 16:20 ` Marc Zyngier
2011-05-26 16:32 ` Peter Zijlstra
2011-05-27 8:01 ` Marc Zyngier
2011-05-26 16:22 ` Marc Zyngier
2011-05-26 17:04 ` Oleg Nesterov
2011-05-26 17:17 ` Peter Zijlstra
2011-05-26 17:23 ` Peter Zijlstra
2011-05-26 17:49 ` Oleg Nesterov
2011-05-27 7:01 ` Yong Zhang
2011-05-27 15:23 ` Santosh Shilimkar
2011-05-27 15:29 ` Marc Zyngier [this message]
2011-05-27 15:30 ` Santosh Shilimkar
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