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

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Date:	Wed, 14 Jul 2010 10:31:12 +0200
From:	Damien Wyart <damien.wyart@...e.fr>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Zeno Davatz <zdavatz@...il.com>, linux-kernel@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: kmemleak, cpu usage jump out of nowhere

Hi,

> 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.

-- 
Damien
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