WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: AW: [Xen-devel] How to use Px/Cx for power saving?

To: Carsten Schiers <carsten@xxxxxxxxxx>
Subject: Re: AW: [Xen-devel] How to use Px/Cx for power saving?
From: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>
Date: Thu, 15 Jan 2009 09:01:30 +0900
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Yu Ke <ke.yu@xxxxxxxxx>
Delivery-date: Wed, 14 Jan 2009 16:02:05 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <7198961.251231945639314.JavaMail.root@uhura>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <7198961.251231945639314.JavaMail.root@uhura>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.19 (X11/20090105)
Hi, Carsten

Thank you for your infomation.
I didn't check the mail, sorry.
It's helpful. Is FREQCTL_none the default value?
If we use FREQCTL_dom0_kernel, xen/guests don't use cpufreq?

Best Regards,

Akio Takebe

Carsten Schiers wrote:
Hi,

cpufreq support can be either handled by xen or dom0-kernel. You have to 
specify cpufreq=xen or
cpufreq=dom0-kernel as parameters when starting the hypervisor.

Kevin Tian wrote yesterday:

> It's intentional since Xen itself supports cpufreq now. To avoid > dependency on dom0's CONFIG_CPU_FREQ and also intrusive > checks on whether external control is enabled in every linux
  > cpufreq drivers, CPU_FREQ in dom0 is silented by default now.
  > It's not a neat approach, but makes sense since xen controlled
  > cpufreq is sure a better model. You can enable CPU_FREQ in
  > dom0 manually though, by removing below dependency.

    > (drivers/cpufreq/Kconfig)
    > config CPU_FREQ
    >        bool "CPU Frequency scaling"
    > ---->  depends on !PROCESSOR_EXTERNAL_CONTROL

  > However once that dependency is removed, there's no automatic
  > check to avoid confliction when dom0 and xen both want to
  > control freq change, and then you should keep an eye yourself.


For AMD, pre-Family 10 CPUs you are supposed to use dom0-kernel, where you can 
encounter problems
with TSC drifts. For other CPUs, I have no knowledge. Family 10 CPUs will have 
P-State invariant
TSCs and will be should be supported by xen cpufreq. C-State handling is 
switched on by cpuidle as
parameter.
Note: xenpm is used to handle xen cpufreq support. In dom0-kernel, you use the 
dom0 tools.

BR,
Carsten.

----- Originalnachricht -----
Von: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>
Gesendet: Mit, 14.1.2009 15:32
An: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx> ; "Tian, Kevin" <kevin.tian@xxxxxxxxx> 
; Yu Ke <ke.yu@xxxxxxxxx>
Betreff: [Xen-devel] How to use Px/Cx for power saving?

Hi,

If we want to use ACPI power saving(Cx/Px), how do we use them?
I tried to turn CONFIG_xxxx of cpufreq  on with linux-2.6.18-xen.hg,
but I couldn't turn them on.
Also xenpm said the following error.

# xenpm get-cpuidle-states
Xen cpuidle is not enabled!
# xenpm get-cpufreq-states
Xen cpufreq is not enabled!

What should I do?
If there are some good documents, please tell me.

Best Regards,

Akio Takebe

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel