[libvirt-users] CPU Resource Reservation using KVM

[Kashyap Chamarthy]

On Mon, Apr 13, 2015 at 01:41:59PM +0530, Jatin Davey wrote:
> On 4/13/2015 1:18 PM, Kashyap Chamarthy wrote:
> >On Mon, Apr 13, 2015 at 12:14:12PM +0530, Jatin Davey wrote:
> >>Hi All
> >>
> >>I am new to KVM world. I have been using VMware for about a year.
> >>
> >>In VMware world we can reserve cpu resources for a VM. Say for instance if
> >>we need 4 vCPUs with a total of 8000 GHz then we can mention this
> >>configuration in vCenter while creating a VM. This guarantees 8000 GHz of
> >>cpu resources for the deployed VM.
> >>
> >>How can i achieve the same thing using KVM ?
> >If you are comfortable with command line, you can look at `virsh` manual
> >page for
> >
> >     setvcpus - change number of virtual CPUs
> >
> >to control how many vCPUs you can allocate.
> >
> >If you're using `virt-manager`, you should be able to control it via UI
> >for a guest under its "Show virtual hardware details" and look for
> >"Processor".
> >
> >
> I have looked at virsh and more specifically "setvcpus".

You mention that info only now.

> We can assign virtual CPUs using it but my question is different. I am
> looking at reserving cpu speed to the virtual cpu's. I know we can
> allocate and modify the amount vcpu's using setvcpus command but how
> can i ask kvm to reserve a particular amount of cpu speed of the host
> core's to the virtual cpus.

Okay. I don't notice an option to regulate CPU freq. But the closest I
see is the 'quota' XML attribute (as part of 'cputune' element) that
will "ensure that all vcpus run at the same speed."

    https://libvirt.org/formatdomain.html#elementsCPUTuning


-- 
/kashyap