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Re: [Xen-devel] Re: Poor performance on HVM (kernbench)

  • To: "Gianluca Guida" <gianluca.guida@xxxxxxxxxxxxx>
  • From: "Todd Deshane" <deshantm@xxxxxxxxx>
  • Date: Thu, 11 Sep 2008 11:35:30 -0400
  • Cc: Muli Ben-Yehuda <MULI@xxxxxxxxxx>, Anthony Liguori <aliguori@xxxxxxxxxx>, xen-devel mailing list <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Thu, 11 Sep 2008 08:39:10 -0700
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On Thu, Sep 11, 2008 at 11:17 AM, Gianluca Guida
<gianluca.guida@xxxxxxxxxxxxx> wrote:
> Hi,
> Gianluca Guida wrote:
>> Todd Deshane wrote:
>>> Xen 3.3 should be an improvement with shadow3 right?
> I made a few test, in an amd64 kernel, with shadow2 and shadow 3.
> Results attached. What you can see is that in 1 vcpu environment the two
> system compare very well (with shadow3 being 1.5% faster that shadow2,
> system time being much lower). It's disturbing that in 2 vcpus, instead, the
> shadow2 is about 11% faster. I'll try to look at that and make the shadow3
> algorithm a bit more linux-friendly but, in general, I don't think that the
> slow down was due *only* to shadow3.
> Was it a 32bit guest? PAE?

The guest is 64 bit

Can you also run kernbench on native for comparison?

We have a fairly similar setup, mine is
Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
4 GB of Ram

How much RAM do you have (native and guest)?

Are all your tests on Xen unstable with the code changes on and off as
you suggested?

What is the backend disk type for your HVM guest?
What is the kernel in your HVM guest?

I will make the same changes to the xen unstable code and re-run
kernbench with shadow3 disabled
on my system.


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