High CPU load on target host after migration

High CPU load on target host after migration

[Thomas Beinicke]

Hi,

I have been toying around with kvm / libvirt / virt-manager and it's migration 
feature.
Both host machines are running a 2.6.33 Kernel.

One host is a Dual Quad Core Intel Xeon E5520  @ 2.27GHz and the other is a 
Dual Quad Core Intel E5420  @ 2.50GHz.

Migrating Linux machines works great but Windows XP SP3 is giving me a 
headache.
The migration process finishes without any crash/error but the CPU load on the 
target host is ~50% on two cores. There is no CPU intensive task running 
inside the VM though.
"Removing" the network card from the VM and migrating it between the two 
machines doesn't seem to trigger the high CPU load.
As network driver I tried the realtek and Red Hat virtio driver but it doesn't 
seem to make a difference.

Any insights on what could cause this situation and how to best debug it?

Cheers,

Thomas

Re: High CPU load on target host after migration

[Thomas Beinicke]

I forgot to mention that I am using qemu-kvm-0.12.3 on all of my machines.
I am also using bridged networking on all hosts.
Is anyone else on the list doing life migration and is facing the same 
problems I mentioned below?

I would really like to debug this further but I need some assistance on how to 
proceed.

Thanks,

Thomas


On Wednesday 28 April 2010 23:14:40 you wrote:
> Hi,
> 
> I have been toying around with kvm / libvirt / virt-manager and it's
> migration feature.
> Both host machines are running a 2.6.33 Kernel.
> 
> One host is a Dual Quad Core Intel Xeon E5520  @ 2.27GHz and the other is a
> Dual Quad Core Intel E5420  @ 2.50GHz.
> 
> Migrating Linux machines works great but Windows XP SP3 is giving me a
> headache.
> The migration process finishes without any crash/error but the CPU load on
> the target host is ~50% on two cores. There is no CPU intensive task
> running inside the VM though.
> "Removing" the network card from the VM and migrating it between the two
> machines doesn't seem to trigger the high CPU load.
> As network driver I tried the realtek and Red Hat virtio driver but it
> doesn't seem to make a difference.
> 
> Any insights on what could cause this situation and how to best debug it?
> 
> Cheers,
> 
> Thomas
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Re: High CPU load on target host after migration

[Avi Kivity]

On 04/29/2010 12:14 AM, Thomas Beinicke wrote:
> Hi,
>
> I have been toying around with kvm / libvirt / virt-manager and it's migration
> feature.
> Both host machines are running a 2.6.33 Kernel.
>
> One host is a Dual Quad Core Intel Xeon E5520  @ 2.27GHz and the other is a
> Dual Quad Core Intel E5420  @ 2.50GHz.
>
> Migrating Linux machines works great but Windows XP SP3 is giving me a
> headache.
> The migration process finishes without any crash/error but the CPU load on the
> target host is ~50% on two cores. There is no CPU intensive task running
> inside the VM though.
> "Removing" the network card from the VM and migrating it between the two
> machines doesn't seem to trigger the high CPU load.
> As network driver I tried the realtek and Red Hat virtio driver but it doesn't
> seem to make a difference.
>
> Any insights on what could cause this situation and how to best debug it?
>
>    

Can you run a profiler and see where qemu (or kvm) is spending its time?

-- 
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