[nova]Bug #1829696: qemu-kvm process takes 100% CPU usage when running redhat/centos 7.6 guest OS

Kashyap Chamarthy kchamart at redhat.com
Thu Jun 20 16:32:09 UTC 2019

On Thu, Jun 20, 2019 at 10:06:11PM +0800, 钱熙 wrote:
> Hi there,


> I am struggling with qemu-kvm 100% CPU usage problem.
> When running redhat or centos 7.6 guest os on vm,
> the cpu usage is very low on vm(almost 100% idle when no tasks run), but on the host,
> qemu-kvm reports 100% cpu busy usage.
> https://bugs.launchpad.net/nova/+bug/1829696
> I opened the bug above, however it did not find some interest.
> After searching some related bugs report,
> I suspect that it is due to the clock settings in vm's domain xml.
> My settings are as follows:
>     <clock offset='utc'>
>       <timer name='rtc' tickpolicy='catchup'/>
>       <timer name='pit' tickpolicy='delay'/>
>       <timer name='hpet' present='no'/>
>     </clock>
> And details about the bug, please see https://bugs.launchpad.net/nova/+bug/1829696

I don't think it is related to clock settings at all.

> It shows that only the version 7.6 of redhat or centos affected by this bug behavior.
> In my cluster, it is OK for versions from redhat or centos 6.8 to 7.5.
> Any clue or suggestion?

Please see DanPB's response in comment#2; I agree with it.  (Note that
I've changed the bug component from 'openstack-nova' --> 'qemu')



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