[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [ovirt-users] Possible sources of cpu steal and countermeasures

From: Nir Soffer
Subject: Re: [ovirt-users] Possible sources of cpu steal and countermeasures
Date: Thu, 5 Dec 2019 02:09:46 +0200

On Wed, Dec 4, 2019 at 6:15 PM <address@hidden> wrote:
> Hi,
> I'm having performance issues with a ovirt installation. It is showing
> high steal (5-10%) for a cpu intensive VM. The hypervisor however has
> more than 65% of his resources idle while the steal is seen inside of
> the VM.
> Even when placing only a single VM on a hypervisor it still receives
> steal (0-2%), even though the hypervisor is not overcommited.
> Hypervisor:
> 2 Socket system in total 2*28(56HT) cores
> VM:
> 30vCPUs (ovirt seems to think its a good idea to make that 15 sockets *
> 2 cores)

I think you can control this in oVirt.

> My questions are:
> a) Could it be that the hypervisor is trying to schedule all 30 cores on
> a single numa node, ie using the HT cores instead of "real" ones and
> this shows up as steal?
> b) Do I need to make VMs this big numa-aware and spread the vm over both
> numa nodes?
> c) Would using the High Performance VM type help in this kind of situation?
> d) General advise: how do I reduce steal in an environment where the
> hypervisor has idle resources
> Any advise would be appreciated.

These questions are mainly about qemu, so adding qemu-discuss.

I think it will help if you share your vm qemu command line, found in:


reply via email to

[Prev in Thread] Current Thread [Next in Thread]