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RE: [Xen-devel] Cpufreq on k8 with xen dom0

To: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>
Subject: RE: [Xen-devel] Cpufreq on k8 with xen dom0
From: geaaru <geaaru@xxxxxxxxx>
Date: Fri, 28 Sep 2007 12:37:13 +0200
Cc: Xen-Devel ML <xen-devel@xxxxxxxxxxxxxxxxxxx>, Goswin von Brederlow <brederlo@xxxxxxxxxxxxxxxxxxxxxxxxxxx>, Bhavana Nagendra <bnagendr@xxxxxxxxxx>
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Hi, i try to use xen-unstable.hg version but doesn't work.

>From dmesg i have this error:

powernow-k8: Found 1 AMD Turion(tm) 64 Mobile Technology ML-30
processors (version 2.00.00)
powernow-k8: BIOS error - no PSB or ACPI _PSS objects
ACPI: (supports S0 S3 S4 S5)

While, if i try to call cpufreq-info i have this output:

cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@xxxxxxxx, please.
analyzing CPU 0:
  no or unknown cpufreq driver is active on this CPU

any idea how can i resolve this problem?


On Thu, 2007-09-27 at 10:04 -0500, Langsdorf, Mark wrote:
> > >  >  is there a patch for xen-source-2.6.20-r3 for use cpufreq on 
> > >> turion64?
> > >> I'm using xen-sources of gentoo portage.
> > >> Thanks in advance.
> > >
> > > It's still in development; there's a version available
> > > that will let you userspace tools in dom0 to monitor 
> > > and control frequency changes but true ondemand dynamic
> > > scaling still needs some work.
> > >
> > > Email me privately if you're interested in helping and
> > > willing to be a test subject.  Thanks.
> > 
> > I'm verry interested. I have xen on my laptop and when on battery mode
> > that totaly drains power. So when traveling I have to boot non XEN
> > limiting me to dom0.
> > 
> > It shouldn't be too hard to write a little application that will scale
> > frequency depending on the sum of cpu usage of all domains. The info
> > is shown in xentop so it should be simple of sampling that once every
> > X second and sclaing for it.
> > 
> > But even a simple "make it slow" option would be just fine.
> The current version of xen-unstable.hg has Keir's rewrite of
> most of Rik's and my code for support PowerNow!.  A dom0 with
> cpufreq support enabled can use the performance, powersave,
> and userspace governors to change frequency. 
> You'll need to build the latest repository of xen-unstable.hg
> and linux-2.6.18.hg with the cpufreq build config options
> enabled, and pass "cpufreq" on the Xen command line.  
> Power management should come up normally, and running
> `echo "powersave" >
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor`
> should force the system to minimum power.  The same command
> with "performance" should set it to maximum power.  The
> same command with "userspace" will create a 
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed file,
> and writing a frequency value to that will cause the system
> to move to the nearest supported frequency to that value.
> A usermode daemon like cpuspeed
> (http://carlthompson.net/Software/CPUSpeed)
> can be modified to use the Xen getcpuinfo sysctl to read
> the Xen usage values and write to the scaling_setspeed file,
> though I haven't had time to do that yet.
> The ondemand governor won't be supported unless getcpuinfo
> becomes a platform op hypercall.  Rik, what's the status
> on that?
> -Mark Langsdorf
> Operating System Research Center

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