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Subject: Re: Hyperthreading
To: Martin.Bligh@us.ibm.com (Martin J. Bligh)
Date: Wed, 17 Apr 2002 23:12:00 +0100 (BST)
Cc: jbourne@MtRoyal.AB.CA (James Bourne), mingo@elte.hu (Ingo Molnar),
        linux-kernel@vger.kernel.org
In-Reply-To: <1833210000.1019077852@flay> from "Martin J. Bligh" at Apr 17, 2002 02:10:52 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> > And, you've gotta like this line:
> > Total of 4 processors activated (14299.95 BogoMIPS).
> 
> Before you get too excited about that, how much performance boost do 
> you actually get by turning on Hyperthreading? ;-)

10-30% typically. I've actually seen code where you can't measure the
improvement because the main cpu code path is precision tuned to the 
cache...
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