[fedora-virt] Virtualization: qemu-kvm: Excessive CPU usage on host

[Justin M. Forbes]

On Tue, 2009-12-15 at 19:31 +0100, Dario Lesca wrote:
> Il giorno mar, 15/12/2009 alle 11.28 -0600, Justin M. Forbes ha scritto:
> > 
> > > Is this normal? 
> > KSM has a penalty in that it requires CPU cycles to scan for usable
> > pages.
> 
> > This should be mitigated by the ksm service turning the scanner off
> > when it is not needed.
> > Do you have any more information on the hardware profile? Is there a
> > smolt profile for this system?
> 
> Yes :
>         http://www.smolts.org/client/show_all/pub_9da3c016-41da-42f1-b2c3-05f31ffb88f5
> 
> > > It's possible do something to improve the situation? 
> > Is the ksmtuned service running? 
> Yes:
>         [root at lesca ~]# /etc/init.d/ksmtuned status
>         ksmtuned (pid  1522) in esecuzione...
> 
> 
> > If not, please turn it on.  Optionally you can also turn off ksm and
> > ksmtuned.
> 
> I have turn off ksm and ksmtuned but the qemu use always 15% cpu... none
> is changed.

This is most likely an manifestation of
https://bugzilla.redhat.com/show_bug.cgi?id=478317 and hopefully we will
have a fix soon.

thanks
Justin