Re: kvm linux guest hanging for minutes at a time

Philipp Hahn
2011-08-10T15:03:50Z

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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
also. He's able to reproduce this problem every time. For me it manifests on
the serial console hanging after reboot, for him it is after the reboot when
a process does a sleep().
The problem occurrs with clocksource=kvm-clock.
After the reboot tsc is disabled with the message "Clocksource tsc unstable
(delta = 137303562 ns)" and is no longer shown in available_clocksource.
When booting with clocksouce=hpet, the system does not hang.

Our trace-cmd data is available from
<http://download.univention.de/download/temp/kvm-clock/kvm-clock.tar.bz2>
including the trace.dat. show-task-states_portmap.txt and
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. The
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
<https://forge.univention.org/bugzilla/show_bug.cgi?id=23258>
--
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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