In-Reply-To: <200509211653.17999.vda@ilport.com.ua>
To: Denis Vlasenko <vda@ilport.com.ua>
Cc: linux-kernel@vger.kernel.org, linux-kernel-owner@vger.kernel.org
Subject: Re: Bogomips on AMD X2 (was Re:)
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From: Robert.Boermans@uk.telex.com
Message-ID: <OFB4729D93.721C31AE-ON80257083.004CBAE1-80257083.004D28F3@telex.com>
Date: Wed, 21 Sep 2005 15:02:51 +0100
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Sender: linux-kernel-owner@vger.kernel.org
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> > I noticed that the bogomips results for the two cores on my machine 
are 
> > consistently not the same, the second one is always reported slightly 
> > faster, it's a small difference and I saw the same in a posted dmesg 
> from 
> > somebody else on the list. Which made me wonder: 
> 
> I guess it's a cache warming effect. Please show the numbers.
>
> Probably not, got this one from a web site, and on this one the first 
core 
> seems to be faster (can't check my own machine it's off and at home and 
> I'm at work.) The difference I get is similar, but always with the 
second 
> one faster. It's the same when using cat on /proc/cpuinfo. Oh and I saw 
it 
> on 2.6.11 and 2.6.12 as supplied with fedora core 4 myself.
> 
> Calibrating delay using timer specific routine.. 4014.73 BogoMIPS 
> (lpj=8029470)
...
> Initializing CPU#1
> Calibrating delay using timer specific routine.. 4005.37 BogoMIPS 
> (lpj=8010751)

Why do you think it cannot be a cache warming effect?
--
vda

----------
Because with this one the first case was the faster one, that would need 
cache cooling :)
But besides that, as far as I remember the actual loop is about 3 
instructions long and will be cache hot in a time that you'd never notice 
in the end result.

Sorry about the formatting, but it's lotus notes :/
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