[libvirt-users] Setting CPU type for a vm

Mauricio Tavares raubvogel at gmail.com
Tue Jul 24 17:11:00 UTC 2012


On Thu, Jul 19, 2012 at 10:01 AM, Daniel P. Berrange
<berrange at redhat.com> wrote:
> On Thu, Jul 19, 2012 at 07:54:49AM -0600, Eric Blake wrote:
>> On 07/18/2012 08:45 PM, Mauricio Tavares wrote:
>> >     I have a Windows XP vm and would like to know how should I set its
>> > cpu so it is seen by the vm as a proper 32bit one. In its xml file, I have
>> >
>> >   <os>
>> >     <type arch='i686' machine='rhel6.2.0'>hvm</type>
>>
>> That's the correct way.
>>
>> > and this is what virsh thinks my vm has:
>> >
>> > [root at vmhost ~]# virsh vcpuinfo xp
>> > VCPU:           0
>>
>> This looks like a bug - a guest cannot exist without at least one vcpu.
>>
>> > CPU:            2
>>
>> That only says your host has 2 cpus that the guest can utilize; it says
>> nothing about what type of cpu the guest will see.
>
> You're mis-interpreting the data here.  'vpucinfo' info repeats these
> four lines of data per VCPU.
>
> So this is saying that the first vCPU, #0, is running running on host
> CPU #2.
>
> The total number of guest CPUs is shown by 'virsh dominfo'
>
> The total number of host CPUs is shown by 'virsh nodeinfo'
>
      Cool. I do take I can specify which cpu I want to use, right?
later on I need to read up on how to scale up the number of CPUs given
to a vm based on its load.

> Daniel
> --
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