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Re: [libvirt] [PATCHv3 4/8] qemu: bulk stats: implement VCPU group



----- Original Message -----
> From: "Peter Krempa" <pkrempa redhat com>
> To: "Francesco Romani" <fromani redhat com>, libvir-list redhat com
> Sent: Tuesday, September 9, 2014 1:56:09 PM
> Subject: Re: [libvirt] [PATCHv3 4/8] qemu: bulk stats: implement VCPU group

> > + * VIR_DOMAIN_STATS_VCPU: Return virtual CPU statistics.
> > + * Due to VCPU hotplug, the vcpu.<num>.* array could be sparse.
> > + * The actual size of the array correspond to "vcpu.current".
> > + * The array size will never exceed "vcpu.maximum".
> > + * The typed parameter keys are in this format:
> > + * "vcpu.current" - current number of online virtual CPUs as unsigned int.
> > + * "vcpu.maximum" - maximum number of online virtual CPUs as unsigned int.
> > + * "vcpu.<num>.state" - state of the virtual CPU <num>, as int
> > + *                      from virVcpuState enum.
> > + * "vcpu.<num>.time" - virtual cpu time spent by virtual CPU <num>
> > + *                     as unsigned long long.
> > + * "vcpu.<num>.cpu" - physical CPU pinned to virtual CPU <num> as int.
> 
> This is not the CPU number the vCPU is pinned to but rather the current
> CPU number where the vCPU is actually running. If you pin it to multiple
> CPUs this may change in the range of the host CPUs the vCPU is pinned
> to. Said this I don't think this is an useful stat.

Right, my bad, I overlooked the docs (started to suspect when saw it changing too often
in my tests..).

I agree this is not very useful, I'll drop it.

> Rather than this I'd like to see the mask of the host CPUs where this
> vCPU is pinned to. (returned as a human readable bitmask string).
> 
> Any thoughts?

Is that the data provided by http://libvirt.org/html/libvirt-libvirt.html#virDomainGetVcpuPinInfo
it isn't? (I'm asking because docs aren't crystal clear for me).

I like this, but I'd also need to do a cross-check on my our code in oVirt.

Will be acceptable to drop the misleading vcpu.<num>.cpu info and to add
the pin info in a new followup patch, in this stats group?

Bests,

-- 
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani


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