xen 3.3.0 cpufreq usage

Hi,

I want to use cpufreq feature provided by xen 3.3.0 with PV domUs.

My system is a Dell PE1950 with Intel(R) Xeon(R) CPU E5345 with power on demand activated in bios.

I use hypervisor and dom0 kernel from xen-3.3.0.tar.gz compilated with make world.

With cpufreq=xen option in grub kernel line i've this xm dmesg output :
(XEN) xen_pminfo: @acpi_cpufreq_cpu_init,HARDWARE addr space

but cat /proc/cpuinfo  doesn't  show lower CPU MHz and stepping is always at his maximum.

I don't know how to use cpufreq=dom0_kernel  because with xen 3.3.0 i can't compile my own dom0 kernel with cpufreq support:
In menuconfig if i select Privileged Guest (domain 0)  then Cpu frequency scaling is disabled in Power maangement support.

in anyway i can't acces through /sys/devices/system/cpu/cpu0/ to cpufreq.

So how works cpufreq with xen 3.3.0  ?
Is cpufreq=xen only limited to amd processor ?


thanks for answers


Cédric L.

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[Tian, Kevin]

cpufreq=xen is enough to activate cpufreq support on Intel processors with EIST feature. However you can't retrieve run-time information by existing dom0 sysfs interface, as dom0 is also virtualized and there's no direct relationship between dom0's vcpus and underlying physical cpus. By far hypercall interface is created for such purpose (tools/libxc/xc_pm.c) and you then can write a small utility to use it. :-)

 

Thanks,

Kevin

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From: xen-users-bounces@... [mailto:xen-users-bounces@...] On Behalf Of lagneau@...
Sent: 2008年9月8日 16:58
To: xen-users@...
Subject: [Xen-users] xen 3.3.0 cpufreq usage

Hi,

I want to use cpufreq feature provided by xen 3.3.0 with PV domUs.

My system is a Dell PE1950 with Intel(R) Xeon(R) CPU E5345 with power on demand activated in bios.

I use hypervisor and dom0 kernel from xen-3.3.0.tar.gz compilated with make world.

With cpufreq=xen option in grub kernel line i've this xm dmesg output :
(XEN) xen_pminfo: @acpi_cpufreq_cpu_init,HARDWARE addr space

but cat /proc/cpuinfo  doesn't  show lower CPU MHz and stepping is always at his maximum.

I don't know how to use cpufreq=dom0_kernel  because with xen 3.3.0 i can't compile my own dom0 kernel with cpufreq support:
In menuconfig if i select Privileged Guest (domain 0)  then Cpu frequency scaling is disabled in Power maangement support.

in anyway i can't acces through /sys/devices/system/cpu/cpu0/ to cpufreq.

So how works cpufreq with xen 3.3.0  ?
Is cpufreq=xen only limited to amd processor ?


thanks for answers


Cédric L.

---

My...o ? You...quoi ? Face...qui ?... Vous ne savez plus comment tre vous-mme ?
Pour Crer, Partager et enfin Gagner ... Dcouvrez iDOO en vido

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