Re: [libvirt-users] setvcpus libvirt 1.2.9

Thomas Stein
Wed, 05 Nov 2014 13:56:45 -0000

Am 05.11.14 14:48, schrieb Eric Blake:
> On 11/05/2014 01:20 PM, Thomas Stein wrote:
>> Am 05.11.14 11:48, schrieb Martin Kletzander:
>>> On Wed, Nov 05, 2014 at 11:35:37AM +0100, Thomas Stein wrote:
>>>> Hello.
>>>>
>>>> I'm struggeling a little bit with the setvcpus command.
I'm trying now
>>>> to get this running for a linux VM. Here is what i have:
>>>>
>>>> <vcpu placement='auto'
current='2'>4</vcpu>
>
> This is one case where xen may be a bit more powerful than current qemu
> support.  Xen supports booting a guest with a promise of a maximum cpu
> larger than what it boots with; but I don't know that qemu does that
> well yet.  For now, with qemu, you pretty much have to boot with all
> cpus enabled, then after the guest is up and running, disable the cpus
> you don't plan to use right away.  CPU hotplug/hot-unplug is still a
> work in progress in qemu (for example, some versions of qemu support
> hotplug but not hot-unplug).  I haven't played much with it myself to
> know what minimum version of libvirt and qemu will do what you want, so
> you may have to do some experimentation.

Thanks. I let you know if my experiments lead to some discoveries.

cheers
t.