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Re: [Xen-users] Xen 3.2 on CentOS calculates AMD cpu frequency incorrect

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Xen 3.2 on CentOS calculates AMD cpu frequency incorrect
From: Kai Schaetzl <maillists@xxxxxxxxxxxxx>
Date: Sun, 03 Aug 2008 20:06:09 +0200
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Kai Schaetzl wrote on Sun, 03 Aug 2008 16:33:22 +0200:

> Is there kernel parameter or something I could use to correct this 
> behavior?

After some more research I have found the correct incantation for this. 
The CentOS/RH kernels seem to have this enabled by default, the kernels 
from xen.org have to be "enabled" with a command-line option to the 
hypervisor-kernel (not the CentOS kernel).
kernel /xen.gz-3.2 cpufreq=dom0-kernel

I'm getting now correct readings of the frequencies. And scaling up on 
demand works. At least in dom0. I'm not so sure if it works for domUs as 
well. A quick test showed no ondemand scaling in dom0 when running a cpu-
intensive task in a domU. Anyone has more experience with this?

Kai

-- 
Kai Schätzl, Berlin, Germany
Get your web at Conactive Internet Services: http://www.conactive.com




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