Re: [Xen-devel] Benchmark in the VM

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Tue, May 22, 2012 at 7:51 AM, suixiufeng <suixiufeng@xxxxxxxxx> wrote:
> Hi,
>    When I run some workloads from SPECCPU2006. I found that the retired
> instruction number vary significantly between VM and PM according to
> xenoprof. For example:
>
>    Workload                                            Insts
>                            Platform
>    435.gromacs (CPU intensive)                4458151
>                 PM
>    435.gromacs                                       151265683
>                     VM
>    450.soplex   (Memory intensive)            760142
>                PM
>     450.soplex                                          23311208
>                        VM
>
> What is the reason? Does Xen use interpret? Thank you!

I take you to mean, "Does Xen emulate guest instructions"?  The answer
is "No", with one exception: for HVM guests, Xen will emulate accesses
to devices, including MMIO and PIO.

There's not really enough information here to even make a guess as to
what might be causing your numbers here; it's not even really clear
what the numbers you're reporting are, as they seem to be instructions
rather than the performance.  If you could give a bit more information
about what kind of guest OS you're running, your setup, how you're
collecting data, and what it means, we might be able to be more
helpful.

 -George

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