[libvirt-users] About the change of a VM's vcpu count in runtime?

[Dennis Chen]

On 05/29/2013 04:28 AM, Eric Blake wrote:
> On 05/28/2013 02:24 PM, Eric Blake wrote:
>
>>> So the question is: is there any method I can't find yet to change the
>>> vcpu count of a running vm dynamically?
>> Wait for newer qemu and libvirt, or else pitch in and help write patches.
> You might not have to wait that long - if you could help test these
> patches, it would be appreciated:
>
> https://www.redhat.com/archives/libvir-list/2013-May/msg01857.html
>
Hi,

After apply the patch, I've made a test. The testing environment as:

virsh # version
Compiled against library: libvirt 1.0.5
Using library: libvirt 1.0.5
Using API: QEMU 1.0.5
Running hypervisor: QEMU 1.5.0

The xml piece of the vm domain:
     <channel type='unix'>
         <source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/>
         <target type='virtio' name='org.qemu.guest_agent.0'/>
     </channel>

the network connection between the vm and host is ok.

Also I installed the qemu-guest-agent in the guest os:
[root at localhost ~]#rpm -qa | grep qemu-guest
qemu-guest-agent-0.12.1.2-2.355.el6.i686

An error happened when I try to offline a guest vcpu in virsh:
virsh # setguestvcpu 8  1 --offline
error: Guest agent is not responding: Guest agent not available for now

Is there some step I missed before I invoke the 'setguestvcpu' command 
in virsh or I need to write a program to hot-plug/unplug the vcpu with 
the help of the new API introduced by this patch? Thanks!

BRs,
Dennis