Hi, I''ve recently installed xen-3.2.1 on my AMD Sempron(tm) machine. It runs gentoo 2.6.21 as dom0 and cpu frequency scaling works in dom0. But inside a domU, cpu frequency scaling is not working. By checking the boot log in domU I found that domU is unable to load the powernow driver: "powernow-k8: BIOS error - no PSB or ACPI _PSS objects" I wonder if it is possible to have cpu frequency scaling support inside domUs? -- Vahid _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
If domU means PV domain in your mail, there''s even no ACPI table exposed to PV domain. HVM domain has one faked by Qemu. Also the value to expose a virtual cpufreq feature is still unclear. Some papers discuss usage as scheduler hint or help real power, but none gets into real product yet. Thanks Kevin ________________________________ From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Vahid Kazempour Sent: 2008年7月25日 8:42 To: xen-users@lists.xensource.com Subject: [Xen-users] cpu frequency scaling in domUs Hi, I''ve recently installed xen-3.2.1 on my AMD Sempron(tm) machine. It runs gentoo 2.6.21 as dom0 and cpu frequency scaling works in dom0. But inside a domU, cpu frequency scaling is not working. By checking the boot log in domU I found that domU is unable to load the powernow driver: "powernow-k8: BIOS error - no PSB or ACPI _PSS objects" I wonder if it is possible to have cpu frequency scaling support inside domUs? -- Vahid _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Is it possible to fake ACPI table in PV domain too? I'm going to use it as a scheduler hint. So, I need it to work in domUs (both PV and HVM domains). Is it possible to create a frontend driver which provides this feature in domUs? Thanks -- Vahid 2008/7/24 Tian, Kevin <kevin.tian@intel.com> If domU means PV domain in your mail, there's even no ACPI table exposed> to PV domain. HVM domain has one faked by Qemu. Also the value to expose > a virtual cpufreq feature is still unclear. Some papers discuss usage as > scheduler hint or help real power, but none gets into real product yet. > > Thanks > Kevin > > ------------------------------ > *From:* xen-users-bounces@lists.xensource.com [mailto: > xen-users-bounces@lists.xensource.com] *On Behalf Of *Vahid Kazempour > *Sent:* 2008年7月25日 8:42 > *To:* xen-users@lists.xensource.com > *Subject:* [Xen-users] cpu frequency scaling in domUs > > Hi, > > I've recently installed xen-3.2.1 on my AMD Sempron(tm) machine. > It runs gentoo 2.6.21 as dom0 and cpu frequency scaling works in dom0. > But inside a domU, cpu frequency scaling is not working. > By checking the boot log in domU I found that domU is unable to load the > powernow driver: > "powernow-k8: BIOS error - no PSB or ACPI _PSS objects" > I wonder if it is possible to have cpu frequency scaling support inside > domUs? > > -- > Vahid > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Yeah, I think it is doable with a tiny driver. Thanks for your email. -- Vahid, On Sun, Jul 27, 2008 at 6:43 PM, Tian, Kevin <kevin.tian@intel.com> wrote:> Do you want to add this feature to upstream as a clean feature, or > only target for some in-house experiment? If the latter, I don't think > that fake ACPI table is necessary, which involves more effort. > Actually you can just write a tiny cpufreq driver in domU, which > simply uses hypercall to communicate with HV directly and is > simply straightforward. > > Thanks, > Kevin > > ------------------------------ > *From:* Vahid Kazempour [mailto:kazempour@gmail.com] > *Sent:* 2008年7月27日 4:13 > *To:* Tian, Kevin > *Subject:* Re: [Xen-users] cpu frequency scaling in domUs > > > Is it possible to fake ACPI table in PV domain too? > I'm going to use it as a scheduler hint. So, I need it to work in domUs > (both PV and HVM domains). > Is it possible to create a frontend driver which provides this feature in > domUs? > > Thanks > -- > Vahid > > 2008/7/24 Tian, Kevin <kevin.tian@intel.com> > >> If domU means PV domain in your mail, there's even no ACPI table exposed >> to PV domain. HVM domain has one faked by Qemu. Also the value to expose >> a virtual cpufreq feature is still unclear. Some papers discuss usage as >> scheduler hint or help real power, but none gets into real product yet. >> >> Thanks >> Kevin >> >> ------------------------------ >> *From:* xen-users-bounces@lists.xensource.com [mailto: >> xen-users-bounces@lists.xensource.com] *On Behalf Of *Vahid Kazempour >> *Sent:* 2008年7月25日 8:42 >> *To:* xen-users@lists.xensource.com >> *Subject:* [Xen-users] cpu frequency scaling in domUs >> >> Hi, >> >> I've recently installed xen-3.2.1 on my AMD Sempron(tm) machine. >> It runs gentoo 2.6.21 as dom0 and cpu frequency scaling works in dom0. >> But inside a domU, cpu frequency scaling is not working. >> By checking the boot log in domU I found that domU is unable to load the >> powernow driver: >> "powernow-k8: BIOS error - no PSB or ACPI _PSS objects" >> I wonder if it is possible to have cpu frequency scaling support inside >> domUs? >> >> -- >> Vahid >> >>_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users