RE: [Xen-devel] cpufreq status information

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> "Tian, Kevin" <kevin.tian@xxxxxxxxx> 08.09.08 15:50 >>>
>>From: Jan Beulich [mailto:jbeulich@xxxxxxxxxx] 
>>How? I can't see where the current frequency a CPU is running at
>>is being exposed.
>
>common/sysctl.c: XEN_SYSCTL_get_pmstat

Ah, okay, I missed that. But - I can't use this from the kernel anyway,
and tools that track the frequency (i.e. KDE sysguard) would need to
be modified in order to make use of this. I'd really prefer /proc/cpuinfo
to correctly reflect this at least in Dom0. And even beyond that - I can't
seem to find any users of the APIs in tools/libxc/xc_pm.c, so these
really appear to be dead stubs.

>Then you have to pin dom0 vCPU to corresponding pCPU, and have
>dom0 with same number as pCPU. I don't think such limitation
>necessary for just retrieving some pCPU information.
>
>Or if you still enable vcpu migration, you have to fake virtual freq
>change notification within dom0 at vcpu migration as pCPU may 
>scale its own freq individually.

Why? All I care about is a snapshot value. It doesn't matter whether
it's stale by the time I get it, there's nothing going to be calculated
from it, apart from statistics.

Jan


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