linux-kernel - Re: kmemleak, cpu usage jump out of nowhere

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Message-ID: <4C3D777F.8090702@cs.helsinki.fi>
Date:	Wed, 14 Jul 2010 11:38:23 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Zeno Davatz <zdavatz@...il.com>, Mike Galbraith <efault@....de>
CC:	Damien Wyart <damien.wyart@...e.fr>, linux-kernel@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>, mingo@...e.hu,
	a.p.zijlstra@...llo.nl
Subject: Re: kmemleak, cpu usage jump out of nowhere

Zeno Davatz wrote:
> On Wed, Jul 14, 2010 at 10:31 AM, Damien Wyart <damien.wyart@...e.fr> wrote:
> 
>>> On Wed, Jul 14, 2010 at 9:12 AM, Zeno Davatz <zdavatz@...il.com> wrote:
>>>> I got a new Intel core-8 i7 processor.
>>>> I am on kernel uname -a
>>>> Linux zenogentoo 2.6.35-rc5 #97 SMP Tue Jul 13 16:13:25 CEST 2010 i686
>>>> Intel(R) Core(TM) i7 CPU 960 @ 3.20GHz GenuineIntel GNU/Linux
>>>> Sometimes in the middle of nowhere all of a sudden all of my 8-cores
>>>> are at 100% CPU usage and my machine really lags and hangs and is not
>>>> useable anymore. Some random process just grabs a bunch CPUs according
>>>> to htop.
>> * Pekka Enberg <penberg@...helsinki.fi> [2010-07-14 11:05]:
>>> Why did you enable CONFIG_DEBUG_KMEMLEAK? Memory leak scanning is
>>> likely the source of these pauses.
>> I am seeing the same problem with a Core i7 920 and 2.6.35-rc5, and I do
>> not have CONFIG_DEBUG_KMEMLEAK enabled, so I think this is not related.
>>
>> I do not see anything special in the logs, just the load becoming mad
>> and almost preventing ssh access. I've been seeing that since the first
>> 2.6.35 rc I tested (-rc2 or -rc3, I don't remember) and I did not have
>> time to report it before but I was surprised nobody else did. No problem
>> with 2.6.34 and 2.6.34.1.
> 
> same with me. My last build I tested was 2.6.34-rc7. No problems
> there. No CPU jumps out of nowhere.
> 
> It is like any application all of a sudden use 400% CPU i.e. htop.

Interesting. Lets CC some scheduler folks for help.

			Pekka
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