Re: Limiting per vCPU Usage

[Daniel P . Berrangé]

On Sun, Sep 20, 2020 at 10:24:41PM +0200, Peter Lieven wrote:
> Hi Qemu folks,
> 
> 
> is there a BCP to limit just the maximum usage of a virtual (KVM) cpu?
> 
> I know that there are many approaches, but as far as I know they all limit 
> the complete qemu process which is far more
> 
> than just the virtual CPUs.
> 
> Is it possible to limit just the vCPU threads and leave threads that
> handle the monitor, vnc, qmp, iothreads, storage backend etc.

Libvirt uses cgroups to achieve what you describe. A cgroup for the
QEMU process as a whole, then create child cgroups, one for each
vCPUs, and a further one for non-vCPU threads. CPU limits are then
applied on the child cgroups.

Regards,
Daniel
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