From mboxrd@z Thu Jan  1 00:00:00 1970
From: Martin Wawro <martin.wawro@gmail.com>
Subject: Re: [User Question] Repeated severe performance problems on guest
Date: Thu, 18 Apr 2013 15:27:45 +0200
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Cc: kvm <kvm@vger.kernel.org>, Marcelo Tosatti <mtosatti@redhat.com>,
	Gleb Natapov <gleb@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
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On 04/18/2013 03:14 PM, Stefan Hajnoczi wrote:

Dear Stefan,

> No answer but some more questions.
>
> Regarding the kvm_stat output, the exits are caused by 68,000
> pagefaults/second (pf_fixed).  Perhaps someone can explain what this
> means?
>
> The host has 8 cores, the guest has 7.  Host pidstat shows qemu-kvm
> consuming 263.9% CPU:
>
> 11:25:27         4017   11.13   34.65  218.12  263.90     7  qemu-kvm
>
> Why is the guest not getting more than 3 CPUs since the host is otherwise idle?

If one waits a little longer, top shows all 7 cores under utilization
(700%). Unfortunately
we have to be quick with the reboots during daytime, because the system
is in
production use and we have not decided yet to completely replace it.


>
> You may want to disable ksmd on the host since you only have 1 guest,
> but I doubt that will fix the main problem:
>
> 11:25:27          100    0.00    7.89    0.00    7.89     7  ksmd

We did that earlier today. No difference.



>
> For details, see https://www.kernel.org/doc/Documentation/vm/ksm.txt.
>
> What is the python process on the host doing?  Is it poking libvirt?
>
> 11:25:27         4558    4.66    3.55    0.00    8.21     7  python
> 11:25:27         3659    3.99    4.55    0.00    8.54     7  libvirtd

That is virt-manager.py, exactly doing that.


Best regards,

Martin

> Stefan