[ovirt-users] Ovirt VM Performance abd CPU times

[Daniel Helgenberger]

On 29.10.2014 11:48, Xavier Naveira wrote:
> On 10/29/2014 11:47 AM, Xavier Naveira wrote:
>> On 10/29/2014 11:40 AM, Daniel Helgenberger wrote:
>>>
>>>
>>> On 29.10.2014 10:21, Xavier Naveira wrote:
>>>> Hi,
>>>>
>>>> We are migrating our ifrastructure from kvm+libvirt hypervisors to
>>>> ovirt.
>>>>
>>>> Everything is working fine but we're noticing that all the qemu-kvm
>>>> processes in the hypervisors take a lot of CPU.
>>> Without further details of the workload this is hard tell. One Reason I
>>> can think of might be KSM [1]. Is it enabled on your cluster(s)? What is
>>> your mem over-commitment setting?
>>>
>>> Note, IIRC the KSM policy is currently hard coded; it will start at 80%
>>> host mem usage.
>>>
>>> [1] http://www.ovirt.org/Sla/host-mom-policy
>>>>
>>>> The typical example is an idle machine, running top from the machine
>>>> itself it reports cpu use percentages below 10% and loads (with 2
>>>> processors) of 0.0x. The process running that machine in the hypervisor
>>>> rports cpu uses in the order of the 80-100%.
>>>>
>>>> Should the values look like this? Why are the idle machines eating up so
>>>> much CPU time?
>>>>
>>>> Thank you.
>>>> Xavier
>>>>
>>>> _______________________________________________
>>>> Users mailing list
>>>> Users at ovirt.org
>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>>
>>>
>>
> Hi, thank you for the answer.
>
> I've been trying to work out some pattern and realized that the VMs
> using that much cpu all are Redhat 5.x, the Readhat 6.x doesn't exhibit
> this kind of high cpu use. (we run only redhat/centos 5.x/6.x on the
> cluster)
What OS are the hosts running? In case of EL6, make sure you have
tuned-0.2.19-13.el6.noarch installed [1].

To further investigate please post Engine, VDSM, libvirt and kernel
versions from the hosts.

[1] https://access.redhat.com/solutions/358033
>
> I'll take a look to the KSM config.
>
> Cheers,
>
> Xavier
>

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Daniel Helgenberger
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