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

  • To: "Daniel Magenheimer" <dan.magenheimer@xxxxxxxxxx>
  • From: "Todd Deshane" <deshantm@xxxxxxxxx>
  • Date: Wed, 10 Sep 2008 17:42:14 -0400
  • Cc: xen-devel mailing list <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Wed, 10 Sep 2008 14:42:37 -0700
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On Wed, Sep 10, 2008 at 5:37 PM, Daniel Magenheimer
<dan.magenheimer@xxxxxxxxxx> wrote:
> This doesn't answer the HVM question but it appears that
> you are running guests with 1 vCPU but comparing against
> a dual-CPU native.  True?

Yes. The intuition is that we don't want to overcommit virtual CPUs
since then you are stressing the schedulers more.

I ran some tests with 2 vCPUs and all the numbers are a bit higher (as
having two CPUs tackling a compile is faster).

Although overcommit (of CPUs and memory ;) is interesting, we leave a
CPU dedicated to the host system (linux/dom0)
on purpose.


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