Re: [ovirt-users] Ovirt VM Performance abd CPU times

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(a)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 >