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Re: [Xen-devel] changeset 8831 gets sockets, cores, and siblings wrong

To: Andrew Theurer <habanero@xxxxxxxxxx>
Subject: Re: [Xen-devel] changeset 8831 gets sockets, cores, and siblings wrong
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 16 Feb 2006 11:45:52 +0000
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On 15 Feb 2006, at 21:21, Andrew Theurer wrote:

FWIW, I noticed that changeset 8831 gets the sockets/cores/siblings incorrect on my system. On 8830 I get 4 sockets per node, 2 cores per socket, and 2 threads per core. On 8831 I get 1 socket per node, 2 cores per socket, and 8 threads per core. Xen boot messages still appear to show four distinct physical cpus (sockets). Just wondering if anyone has noticed this behavior.

This all stems from an incorrect value for smp_num_siblings. This could come from one of two places: 1. Do you get a message 'WARNING: 8 siblings found for CPUx, should be 2' during boot? If so, smpboot.c is screwing up the smp_num_siblings calculation. 2. Otherwise, detect_ht() in arch/x86/cpu/common.c must be the culprit, and you'll need to add some tracing to it to find out where the value '8' is coming from.

 -- Keir

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