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From: Steven Rostedt <rostedt@goodmis.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Brown, Len" <len.brown@intel.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
	Adam Belay <abelay@novell.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>, Andi Kleen <ak@suse.de>
Subject: Re: [PATCH] Kick CPUS that might be sleeping in cpus_idle_wait
Date: Thu, 10 Jan 2008 09:43:46 -0500 (EST)	[thread overview]
Message-ID: <Pine.LNX.4.58.0801100936320.6420@gandalf.stny.rr.com> (raw)
In-Reply-To: <20080110134539.GD5886@elte.hu>



On Thu, 10 Jan 2008, Ingo Molnar wrote:
> > 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?

It only triggeres with the switching of the idle governors. And not just
one, you need to switch twice. The first loading of a governor does not
call cpu_idle_wait, but the second one does. NO_HZ must also be enabled,
plus this needs to happen when no events or threads are scheduled to run
on a CPU, which limits this to boot up.

Also, this only seems to happen on my 2x2 (4way) and only once in a while.

I'm surprised that I'm the only one so far to report it. I can boot up the
2.6.23 kernel on this box to see if it also hangs sometimes. But, as I
said, it may take several hundreds of tries to see it.

-- Steve


  reply	other threads:[~2008-01-10 14:44 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-08  2:27 [RFC PATCH] kick sleeping idle CPUS on cpu_idle_wait Steven Rostedt
2008-01-08  3:33 ` Andi Kleen
2008-01-09 20:42   ` [PATCH] Kick CPUS that might be sleeping in cpus_idle_wait Steven Rostedt
2008-01-09 22:12     ` Steven Rostedt
2008-01-10 13:45       ` Ingo Molnar
2008-01-10 14:43         ` Steven Rostedt [this message]
2008-01-10 17:31           ` Pallipadi, Venkatesh
2008-01-10 18:03             ` Steven Rostedt
2008-01-09 23:42     ` Andrew Morton
2008-01-10  0:05       ` Steven Rostedt
2008-01-10  0:12     ` Pallipadi, Venkatesh
     [not found]     ` <B5B0CFF685D7DF46A05CF1678CFB42ED20E00653@orsmsx423.amr.corp.intel.com>
2008-02-08  1:05       ` [PATCH] x86: Simplify cpu_idle_wait Venki Pallipadi
2008-02-08 10:28         ` Andi Kleen
2008-02-08 17:24           ` Venki Pallipadi
2008-02-08 18:45             ` Andi Kleen
2008-02-09  9:33             ` Thomas Gleixner
2008-04-10 16:49               ` Venki Pallipadi

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