[libvirt-users] Hard limit for the cpu usage of a VM

[Eric Blake]

On 10/24/2011 02:54 PM, sethuraman subbiah wrote:

> [root at sbc11 ssubbiah]# virsh schedinfo rubis_ws --set vcpu_quota=50
> Scheduler      : posix
> error: invalid scheduler option: vcpu_quota=50
>
> I get the same error for "virsh schedinfo rubies_ws --set vcpu_quota 50" .
>
> I find that my version is 0.9.4.
>
> [root at sbc11 ssubbiah]# virsh --version
> 0.9.4
>
> Should I do some modifications,enable options or add some patch to get the capability to set cap ? Thanks for all your help.

I found this comment in the code:

     /* If we does not know VCPU<->PID mapping or all vcpu runs in the same
      * thread, we cannot control each vcpu. So we only modify cpu bandwidth
      * when each vcpu has a separated thread.
	
I think that means that in order to use CPU caps, you have to also use 
<vcpupin> to call out the host CPU pinning to be used by the guest VCPUS.

The original implementation was here, although I don't see much 
documentation in that patch series. 
https://www.redhat.com/archives/libvir-list/2011-July/msg01389.html

Wen, can you help out here?

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org