linux-kernel - Re: [PATCH] Kick CPUS that might be sleeping in cpus_idle

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Date:	Thu, 10 Jan 2008 14:45:43 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Brown, Len" <len.brown@...el.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Adam Belay <abelay@...ell.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andi Kleen <ak@...e.de>
Subject: Re: [PATCH] Kick CPUS that might be sleeping in cpus_idle_wait


* Steven Rostedt <rostedt@...dmis.org> 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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