AW: Re: AW: [Xen-users] cpu frequency scaling in xen 3.3.1

["Carsten Schiers" <carsten@xxxxxxxxxx>]

Latest 3.3 Xen docs will explain the parameters, but don't give the 
background information. It's
barried deep in the Xen-Devel list. I don't think <Fam10h families will 
be ever supported diretctly
in the hypervisor, but there is no necessity to do so. The modified 
ondemand governor uses a hypercall
to get idle times and follow the policy. 

Building cpufreq management and the necessary drivers (e.g. powernow-k8, 
cpufreq_ondemand,...) is a
bit tricky. Follow the link. Eventualy you also need to patcht he 
Kconfig file a bit...

BR,
Carsten.

-----Ursprüngliche Nachricht-----
Von: Florian Gleixner [mailto:flo@xxxxxxxxx] 
Gesendet: Sonntag, 29. März 2009 18:19
An: Carsten Schiers
Cc: xen-users
Betreff: Re: AW: [Xen-users] cpu frequency scaling in xen 3.3.1

Thanks!

Is there a document that i have overseen? Or is the documentation 
missing?
Cpu frequency scaling inside the hypervisor would be great. Where can i 
vote for that my CPU model will be included?
I'll try to get the powernow-k8.ko build now. Opensuse 11.1 has it for 
the non-xen kernel but did not include it in the xen enabled kernel.

Florian

Carsten Schiers wrote:
> Florian,
> 
> handling of P-States for AMD CPUs is only possible in xen hypervisor 
> from CPU Fam 10h on.
> The 5050e is family 0Fh.
> 
> The alternative is using frequency handling in dom0, by specifying 
> cpufreq=dom0-kernel in the hypervisor start line. You need 
> powernow-k8.ko then in dom0 and can use e.g. the dom0 ondemand 
> governor (by calling cpufreq-set -g ondemand).
> 
> Assuming you are German, please see
> http://www.ctserver.org/ftopic2437.html for some details.
> It is a bit tricky and still not working 100% without log warnings for 

> me and my 4050e.
> 
> BR,
> Carsten.
> 
> -----Ursprüngliche Nachricht-----
> Von: Florian Gleixner [mailto:flo@xxxxxxxxx]
> Gesendet: Sonntag, 29. März 2009 12:03
> An: xen-users@xxxxxxxxxxxxxxxxxxx
> Betreff: [Xen-users] cpu frequency scaling in xen 3.3.1
> 
> Hi,
> 
> i read the xenpm wiki page, but i cannot use the "p-states". xenpm
> shows:
> 
> xenpm
> cpu id               : 0
> total C-states       : 2
> idle time(ms)        : 1776034
> C0                   : transition [00000000000000000000]
>                        residency  [00000000000000000000 ms]
> C1                   : transition [00000000000000260278]
>                        residency  [00000000000000000000 ms]
> 
> cpu id               : 1
> total C-states       : 0
> idle time(ms)        : 1771123
> 
> [CPU0] failed to get P-states statistics information [CPU1] failed to 
> get P-states statistics information
> 
> /proc/cpuinfo shows:
> model name      : AMD Athlon(tm) Dual Core Processor 5050e
> 
> without xen i can scale the frequency perfectly. Are p-states for this 

> CPU model unsupported? My grub line is:
>     kernel /xen.gz cpufreq=xen cpuidle ...
> 
> Thanks for the help!
> 
> Florian
> 
> 
> 
> 




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