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Re: [Xen-devel] Latest unstable detects cpu speed incorrectly

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Subject: Re: [Xen-devel] Latest unstable detects cpu speed incorrectly
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Tue, 27 Oct 2009 15:31:45 -0700
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Valtteri Kiviniemi <valtteri.kiviniemi@xxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
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On 10/27/09 15:15, Dan Magenheimer wrote:
> The downside is
> of course is that the extra multiply would need to be
> done on every emulated TSC (unless maybe it could be folded
> into the other required scaling?)
>   

Given the speed of multipliers compared to everything else on the
emulation path, I don't think it would be measurable let alone
noticeable (my measurements show that multiply is trivial compared to a
native rdtsc).

The nice thing about a fixed 1GHz emulated tsc is that it makes it clear
that it is emulated.

    J

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