Re: [Xen-devel] Performance difference between Xen versions

[John Weekes <lists.xen@xxxxxxxxxxxxxxxxxx>]

On 5/2/2011 8:04 PM, Tian, Kevin wrote:
> you won't know the exact frequency bumped up in the turbo mode, as it's all 
> handled
> by the CPU itself. what xen can do is just to tell the cpu now I'm OK to enter 
> turbo
> mode, which is 2268000 (1M higher than normal P0). Then CPU will decide whether
> current code can be overclocked based on various conditions, such as TDP, other
> core activities in the same package, ...
>
> One possibility to verify that turbo mode does work is to run a CPU intensive 
> workload
> on one core, while keeping other cores mostly idle. Then choose cpufreq governor
> to be performance, and then compare your benchmark when BIOS turbo mode is
> on/off. This should give you some feeling whether turbo mode works on your 
> platform.
Thanks for the response, Kevin.

It's good to know that I can check turbo by looking to see if it's in 
the 1000hz-higher mode. It's a little strange to me that the true MHz 
level of the turbo wouldn't be known/shown, but I can live with that, as 
the actual performance is what counts. I'll run those benches.
-John

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