Re: [PATCH] Kick CPUS that might be sleeping in cpus_idle_wait

From: Ingo Molnar
Date: Thu Jan 10 2008 - 08:46:20 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Wed, 2008-01-09 at 15:42 -0500, Steven Rostedt wrote:
> > This patch is different than the first patch I sent out.
> > This one just sends an IPI to all CPUS that don't check in after 1 sec.
> >
> >
> > Sometimes cpu_idle_wait gets stuck because it might miss CPUS that are
> > already in idle, have no tasks waiting to run and have no interrupts
> > going to them. This is common on bootup when switching cpu idle
> > governors.
> >
> > This patch gives those CPUS that don't check in an IPI kick.
>
> FYI, I just hit this hang on 2.6.24-rc6 without any extra patches. So,
> unless 2.6.24-rc7 did anything to fix this issue, this is a high
> priority bug (IMHO).

i'm wondering why this only triggered now. Is this something new in
2.6.24?

Ingo
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