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Re: [xen-devel] System time monotonicity

To: "dan.magenheimer@xxxxxxxxxx" <dan.magenheimer@xxxxxxxxxx>, Dave Winchell <dwinchell@xxxxxxxxxxxxxxx>
Subject: Re: [xen-devel] System time monotonicity
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 21 Apr 2008 20:31:06 +0100
Cc: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Tian, Kevin" <kevin.tian@xxxxxxxxx>
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On 21/4/08 20:26, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> Since my system is 3.0 Ghz, HPET read averages on the order of
> 3 usec, which is what my previous measure showed.
> I suspect that Dave's measurements and mine are "both right"
> and that read overhead of HPET varies on different systems.

That would make sense. HPET accesses have to go all the way to the
southbridge, and that's bound to vary a lot between chipsets let alone
across the very different interconnect topologies of AMD vs Intel.

 -- Keir

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