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Subject: RE: Problem determining number of CPUs
From: Jesper Juhl <jju@dif.dk>
To: linux-kernel@vger.kernel.org
Cc: nagyt@otpbank.hu, Matt_Domsch@Dell.com
In-Reply-To: <20BF5713E14D5B48AA289F72BD372D6821CBA0@AUSXMPC122.aus.amer.dell.com>
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Date: 21 Aug 2002 16:37:14 +0200
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On Wed, 2002-08-21 at 16:20, Matt_Domsch@Dell.com wrote:
> > Linux kernel versions 2.4.18, 2.4.19, 2.4.20pre4 do not determine
> > correctly the number of CPUs on our system. We see 8 CPUs 
> > instead of 4,
> > however the system works.
> > 
> > Our machine: Dell PowerEdge 6600, 4 Xeon 1400 Mhz, 4GB RAM
> 
> Yes, this is expected behavior due to hyperthreaded processors.
> http://lists.us.dell.com/pipermail/linux-poweredge/2002-July/003465.html
> 

I'm aware that hyperthreading makes each CPU appear as two. But wouldn't
it be possible to determine this fact and report it to the user to avoid
confusion (not everyone knows about hyperthreading) ?

In the case of 4 HT capable CPU's it could be reported like 

8 CPUs (4 physical) 

or something like that to indicate that there is nothing wrong and the
kernel is simply taking advantage of hyperthreading.

Just my two euro-cents...


/Jesper Juhl


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