Re: Discordant results between UnixBench and nBench

[Avi Kivity <avi@redhat.com>]

On 12/23/2009 02:55 PM, Matthieu Olivier wrote:
>
> I can only see 4 cores in /proc/cpuinfo.
> According the caract page, there is no hyperthreading.
>
> ->  http://ark.intel.com/Product.aspx?id=35130
>
>    

In this case the plateau at 4 guests is perfectly understandable.

> I also wonder why the host can still get more CPU ressources over 4
> threads? I guess the purpose of both benchmarks is to overload the
> CPU, so why they can't reach the max?
>    

Probably a problem with the benchmark itself.

> I suposed that the FPU was able to handle at least 2 operations the
> same time, or maybe hyperthreading was included, but I can't check the
> first part, and the second isn't true.
>
> Or maybe current x86 processors can handel very well these old
> benchmarks. I can't really say :/
>    

No, you should see the same plateau as with kvm.  The processor can't 
run two threads at once.

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