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Re: [Xen-devel] RFC: large system support - 128 CPUs

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] RFC: large system support - 128 CPUs
From: Bill Burns <bburns@xxxxxxxxxx>
Date: Wed, 13 Aug 2008 06:23:13 -0400
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxx>
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Keir Fraser wrote:
> On 13/8/08 09:22, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:
>> At 09:21 +0100 on 13 Aug (1218619274), Jan Beulich wrote:
>>> Both seem to be hacks to get to 128 CPUs, without consideration of how
>>> to go beyond that
>> I think the shadow_page_info one is a general fix for my implicit
>> assumption that sizeof(cpumask_t) == sizeof (long).
> Do some fields after the cpumask need to line up in both structures? Placing
> a dummy cpumask in the shadow_page structure might make most sense.

Yes, there is a check that a field of page_info and a
field of the shadow_page_info are at the same offset.
Both compile time checks are in private.h

> For the other one I'll have to think a bit. The need for GDT entries per CPU
> currently obviously means scaling much past a few hundred CPUs is going to
> be difficult.

Yes, would like something better here. And as I said, we
don't know yet that just adding the additional page solves


>  -- Keir

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