From mboxrd@z Thu Jan  1 00:00:00 1970
From: Philipp Hahn <hahn@univention.de>
Subject: Re: kvm linux guest hanging for minutes at a time
Date: Wed, 10 Aug 2011 17:03:36 +0200
Message-ID: <201108101703.46761.hahn@univention.de>
References: <201108070806.59194.thomas@fjellstrom.ca> <4E414615.8030201@redhat.com> <201108090846.14525.thomas@fjellstrom.ca>
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To: Avi Kivity <avi@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
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Hi,

> > > On August 9, 2011, Avi Kivity wrote:
> > > >  Yikes.  Please trace such a hang according to
> > > >  http://www.linux-kvm.org/page/Tracing.

I have observed the same problem multiple times now and a college of mine=20
also. He's able to reproduce this problem every time. For me it manifests o=
n=20
the serial console hanging after reboot, for him it is after the reboot whe=
n=20
a process does a sleep().
The problem occurrs with clocksource=3Dkvm-clock.
After the reboot tsc is disabled with the message "Clocksource tsc unstable=
=20
(delta =3D 137303562 ns)" and is no longer shown in available_clocksource.
When booting with clocksouce=3Dhpet, the system does not hang.

Our trace-cmd data is available from=20
<http://download.univention.de/download/temp/kvm-clock/kvm-clock.tar.bz2>
including the trace.dat. show-task-states_portmap.txt and=20
show-task-states_syslogd.txt contain the captures output of Alt-SysRq-t.

Both host and guest are running an 2.6.32.x amd64 kernel, qemu is 0.14.1. T=
he=20
system is currently not in production and can be used for experiments.

Sincerely
Philipp Hahn

PS: This issue is tracked in out German bugtracker at=20
<https://forge.univention.org/bugzilla/show_bug.cgi?id=3D23258>
=2D-=20
Philipp Hahn           Open Source Software Engineer      hahn@univention.de
Univention GmbH        Linux for Your Business        fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/

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