Re: [libvirt-users] Hard limit for the cpu usage of a VM
At 10/25/2011 05:13 AM, Eric Blake Write:
On 10/24/2011 02:54 PM, sethuraman subbiah wrote:
> [root@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@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.
VCPU<->PID mapping is the thread id for each vcpu. qemu-kvm supports this
feature. We use monitor command query-cpus to get VCPU<->PID mapping in
libvirt(the function is: qemuProcessDetectVcpuPIDs()).
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?
It seems that the kernel does not support it. The cfs bandwidth was merged into
kernel tree about some months ago.
Thanks
Wen Congyang