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Re: [Xen-devel] [PATCH] initialize some more cpuinfo fields

To: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] initialize some more cpuinfo fields
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 8 May 2006 14:46:23 +0100
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On 8 May 2006, at 14:10, Jan Beulich wrote:

Namely preventing systems to look like single-socket ones with many cores (because all CPUs show physical ID being

Is it a problem to look like a many-core processor? Given that VCPUS can get moved around between physical CPUs to load-balance, it doesn't make much sense to take the physical IDs of CPUs that VCPUs happen to run on when they boot.

If the many-core appearance is a problem then we could synthesise different physical IDs for VCPUs (probably by forcing physical ID to VCPU number).

The only exception to this 'lie' could perhaps be domain0 in some situations, if we guarantee to run a dom0 VCPU on every physical CPU and never change the pinning. Then calling identify_cpu() for each VCPU makes sense, as does parsing SRAT data or otherwise obtaining NUMA info via a Xen hypercall.

 -- Keir

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