linux-kernel - Re: Not all logical processors activated on Dual Core Xeon (== no Hyperthreading)

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Message-ID: <p73odbvowap.fsf@bingen.suse.de>
Date:	Wed, 09 Jan 2008 16:25:50 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	VUB Stefan Seidel <sseidel@....de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Not all logical processors activated on Dual Core Xeon (== no Hyperthreading)

VUB Stefan Seidel <sseidel@....de> writes:

> I have the following system here: two dual-core Xeon 5130 on an Intel
> S5000V-SA motherboard. The kernel detects 4 CPUs, from what I learn
> through /proc/cpuinfo, these are the 4 cores (two per
> package). However, I think it should be 8 logical processors, because
> the Xeons should be able to do Hyperthreading (or

Core2 Duo based Xeons do not support Hyper Threading.

> ===========================
> but acpidump shows 8 CPUs in multiple locations:

That's likely because the BIOS supports Quad Core CPUs, but does
not disable the excessive objects if you only plug in Dual Core

-Andi
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