From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akio Takebe Subject: Re: AW: How to use Px/Cx for power saving? Date: Thu, 15 Jan 2009 09:01:30 +0900 Message-ID: <496E7CDA.7010308@jp.fujitsu.com> References: <7198961.251231945639314.JavaMail.root@uhura> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <7198961.251231945639314.JavaMail.root@uhura> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Carsten Schiers Cc: "Tian, Kevin" , xen-devel , Yu Ke List-Id: xen-devel@lists.xenproject.org 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 > Gesendet: Mit, 14.1.2009 15:32 > An: xen-devel ; "Tian, Kevin" ; Yu Ke > 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@lists.xensource.com > http://lists.xensource.com/xen-devel >