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Re: [Xen-devel] Why is cpu-to-node mapping different between Xen 4.0.2-r

To: Dante Cinco <dantecinco@xxxxxxxxx>
Subject: Re: [Xen-devel] Why is cpu-to-node mapping different between Xen 4.0.2-rc1-pre and Xen 4.1-unstable?
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Thu, 28 Oct 2010 10:25:08 +0100
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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At 21:58 +0100 on 27 Oct (1288216729), Dante Cinco wrote:
> My system is a dual Xeon E5540 (Nehalem) HP Proliant DL380G6. When
> switching between Xen 4.0.2-rc1-pre and Xen 4.1-unstable I noticed
> that the NUMA info as shown by the Xen 'u' debug-key is different.
> More specifically, the CPU to node mapping is alternating for 4.0.2
> and grouped sequentially for 4.1. This difference affects the
> allocation (wrt node/socket) of pinned VCPUs to the guest domain.

Yes; this change was deliberate.  The mapping of pcpu numbers to
core/socket/node used to depend on the BIOS of the particular machine;
now it's a consistent order on all machines. 



Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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