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[Xen-devel] Re: TSC scaling and softtsc reprise, and PROPOSAL

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>, "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: TSC scaling and softtsc reprise, and PROPOSAL
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 27 Jul 2009 23:39:46 +0100
Cc: "Dong, Eddie" <eddie.dong@xxxxxxxxx>, John Levon <levon@xxxxxxxxxxxxxxxxx>
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On 27/07/2009 23:14, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

>> Yes, then it sounds like they virtualise it for apps too.
>> Also there is an
>> option to virtualise the TSC at a specified frequency -- that would be
>> pretty weird if it applied only to guest-OS RDTSCs but not
>> guest-app RDTSCs.
>> Interesting...
> And further, the frequency is "sticky" across migration, with
> the frequency set to whatever machine the VM originated on.
> I'd be inclined to just use Xen system time and thus
> the TSC frequency would be always 1GHz on all systems.

Well that is what softtsc does already, albeit only for HVM guests so far.

 -- Keir

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