From: Jan Niehusmann <jan@gondor.com>
To: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org
Subject: Re: KVM guest lockup
Date: Sat, 20 Dec 2008 13:15:23 +0100 [thread overview]
Message-ID: <giinkr$lg$1@ger.gmane.org> (raw)
In-Reply-To: <20081219174401.GA2730@squirrel.roonstrasse.net>
Max Kellermann wrote:
> I am running a KVM enabled AMD64 kernel, version 2.6.26 and 2.6.27
> (Debian kernel). The guest has been tested with 2.6.26 up to
> 2.6.28-rc8.
>
> Whenever I put high load on the guest (git-svn is quite good at
> triggering the problem), it becomes unresponsive after a few minutes.
> After a while, a "soft lockup" message appears on serial console, with
> a ridiculously large time span, machine still unresponsive.
You mean something like "BUG: soft lockup - CPU#0 stuck for 1179869794s!"?
I had similar lockups, also on 2.6.26 (amd64).
It turned out to be related to frequency scaling on the host. With
frequency scaling enabled, I was able to lock up the VM within minutes
by periodically switching between full load and idle. (running burnMMX
for a few seconds and then sleeping for a few seconds in a loop)
After setting scaling_min_freq to the same value as scaling_max_freq,
virtual machines became rock solid.
BTW often the lockups were not complete, but the VM resumed work after a
while. (IIRC, ~1/2 hour, for sure much less than 1179869794s :-) )
Jan
next prev parent reply other threads:[~2008-12-20 12:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-19 17:44 KVM guest lockup Max Kellermann
2008-12-20 12:15 ` Jan Niehusmann [this message]
2008-12-21 11:55 ` Jan Niehusmann
2008-12-22 10:57 ` Max Kellermann
2009-01-12 17:09 ` Mark McLoughlin
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