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Re: [Xen-devel] CAP and performance problem

On 06/06/13 11:39, Juergen Gross wrote:
On 06.06.2013 10:57, Massimo Canonico wrote:

On 06/06/2013 10:37 AM, Dario Faggioli wrote:
On mer, 2013-06-05 at 19:05 +0200, Massimo Canonico wrote:
Hi Dario,
and thanks for these test.

I forgot to ask you which xen version has beed used for your experiments.

Yeah, me too! :-)

I'm using xen-unstable, pulled yesterday (commit id
e430510e5cbbfcdc1077739292def633e70fedea), compiled and installed on a
Debian unstable system. Dom0 kernel is a bit old, as it's a 3.6.

What about you?
xen 4.2.2
kernel dom0: 3.8.11-200.fc18.x86_64

Just had an idea: is there any other load on the system during your test (other domains, dom0 load)? If not, it could be that the power management is reducing the cpu speed during idle (when the cap applies). This could lead to reduced
performance overall.

You can test this by setting the xen hypervisor boot option


and run your test again (with and without cap).

Ah, genius Juergen!  That would make total sense.


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