Xen devel - Jun 2008 - Support for CPU frequency scaling in Xen

Hi,

Does Xen provide support for CPU frequency scaling?
If there exists such support, from which version they support it?
Otherwise what problems do exist in support frequency scaling in Xen?

Thanks,
Vahid


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On Tue, Jun 3, 2008 at 9:24 PM, Vahid Kazempour <kazempour@gmail.com>
wrote:
> Hi,
>
> Does Xen provide support for CPU frequency scaling?
> If there exists such support, from which version they support it?
In short, yes but YMMV. I saw a few patches on the list that added
frequency scaling to the hypervisor itself but I don''t know the
current status for that. They should be in xen-unstable.

Another option is to set ''cpufreq=dom0-kernel'' as an option
for xen
and run cpufreqd in dom0. I have tested this on Intel''s Core2 Duo and
AMD''s Opterons. Xen 3.2.1 should have what you need but it is quite
possible that a previous version will also work.

Cheers,
Niraj
> Otherwise what problems do exist in support frequency scaling in Xen?
>
> Thanks,
> Vahid
>
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>
>


-- 
http://www.hpl.hp.com/personal/Niraj_Tolia/

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> > Does Xen provide support for CPU frequency scaling?
> > If there exists such support, from which version they support it?
> 
> In short, yes but YMMV. I saw a few patches on the list that added
> frequency scaling to the hypervisor itself but I don''t know the
> current status for that. They should be in xen-unstable.
Currently, only Intel is supported in xen-unstable.  
There''s a patch under development for AMD Phenom and
3rd generation Operton (the Barcelona quad-cores) but I
haven''t sent it upstream.

Anyone who has a quad-core AMD processor and who is
interested in testing is welcome to email me for the
patch.

-Mark Langsdorf
Operating System Research Center
AMD


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>From:Niraj Tolia
>Sent: 2008年6月4日 14:04
>
>On Tue, Jun 3, 2008 at 9:24 PM, Vahid Kazempour 
><kazempour@gmail.com> wrote:
>> Hi,
>>
>> Does Xen provide support for CPU frequency scaling?
>> If there exists such support, from which version they support it?
>
>In short, yes but YMMV. I saw a few patches on the list that added
>frequency scaling to the hypervisor itself but I don''t know the
>current status for that. They should be in xen-unstable.
You can try this feature with Xen-17650 and dom0-548. Currently
this feature is by default disabled, and you need still enable
CONFIG_CPU_FREQ in dom0''s config file and add a "cpufreq=xen"
in xen''s cmdline to activate this feature. We plan to enable dom0
config option by default a bit later, after making more test. So if
you''d like to try it on your platform, it''s also appreciated.

Thanks,
Kevin

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