Soft lockups and cpu frequency scaling

[Martin Schmitt <mas@scsy.de>]

All,

I'm running a manually compiled KVM on CentOS 5.4. The KVM installation
has been carried over from CentOS 5.3, when KVM wasn't distributed with
the OS. (I tried to migrate to CentOS 5.4 native KVM support, but wasn't
able to get along with RedHat's interpretation of KVM.)

The KVM version used is 88, on Kernel 2.6.18-128.7.1.el5, as KVM doesn't
seem to compile on CentOS' current 2.6.18-164.9.1.el5.

Only on CentOS guests, I see very frequent "soft lockup" messages and
excessively hanging KVM instances. Long-term stability is fine (several
months uptime), but disturbed by the hangs. The problem already was
there on CentOS 5.3 as well. With the Debian guests on the same host, I
have never had any apparent problems.

A number of google results suggest that I should work with CPU scaling
on the CentOS guest systems, but unfortunately, CPU scaling is not
available in my guests. So, here's my question: How do I enable CPU
scaling in KVM guests? Or is there any other measure against these soft
lockups that you can recommend?

Thanks everyone,

-martin

-- 
Martin Schmitt / Schmitt Systemberatung / www.scsy.de
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