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Re: [Xen-devel] Fwd: Re: struct page field arrangement

To: Jan Beulich <jbeulich@xxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Fwd: Re: struct page field arrangement
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Fri, 16 Mar 2007 12:37:44 +0000
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On 16/3/07 11:58, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> Of course we could back out that changeset, but one of the reasons for
> submitting it was to get closer to native.

None of the fixes sound straightforward. :-)

I'd suggest we back out the mm/Kconfig change for 3.0.5 (since that is
close, and I'm not super confident that we'd get any of your proposed fixes
correct first time) and then have a go at supporting split-ptlock in 3.0.6

The situation after all is that our scalability beyond 4 VCPUs is currently
almost certainly bottlenecked by conservative locking in Xen rather than by
per-mm locking in Linux. So we're looking at complicating the Linux code
close to a Xen release for no actual user benefit.

 -- Keir

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