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

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, "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: Tue, 28 Jul 2009 16:58:57 +0100
Cc: "Dong, Eddie" <eddie.dong@xxxxxxxxx>, John Levon <levon@xxxxxxxxxxxxxxxxx>
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On 28/07/2009 16:46, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> Savvy system admins (who know every app in their
> data center and/or are willing to take the risk
> for better performance) should be able to easily
> disable softtsc though on all servers with a xen boot
> option, or on a per VM basis.
> We could quibble about details (maybe softtsc
> should only be automatically enabled on SMP guests
> or on 64-bit SMP guests or ?? ) but I suspect
> that just creates a mess and IMHO we should just
> bite the bullet.

I can live with that, if it is driven from the xend toolstack. It will have
to default off in the hypervisor for compatibility with old saved images.

 -- Keir

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