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Date: Sat, 5 Sep 1998 09:39:04 -0400 (EDT)
From: "D. Sen" <dsen AT research DOT att DOT com>
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To: Michael Hanke <hanke AT nada DOT kth DOT se>
cc: Vincent Diepeveen <diep AT xs4all DOT nl>,
        Krzysztof Strasburger <strasbur AT chkw386 DOT ch DOT pwr DOT wroc DOT pl>,
        beastium-list AT Desk DOT nl
Subject: Re: pgcc and your remarks
In-Reply-To: <Pine.GSO.3.95.980905151126.11076A-100000@c2m2-17.nada.kth.se>
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Sender: Marc Lehmann <pcg AT goof DOT com>
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This seems highly interesting. Could you post some example
code to show how you get the 200-300% improvement. Are
you talking inline assembler code? Also, do
you refer to the Intel documentation to take advantage of
the hardware structure or is this documented somewhere else?

DS
> Maybe, my point of view is a little bit different. I am on this
> mailing list not for the long time. So I apologize...
> 
> As far as I noticed, the improvement in speed is something like 10%.
> Maybe, it's impressive, but not so much. I found out that the real
> thing is to take advantage of the  c o m p l e t e  hardware
> structure (Regs, L1, L2, latency etc). By using these dependencies
> carefully
> an improvement by 200-300% is possible. Since I am using my PC (AMD
> K5 based) for number crunching, the heart of all efforts is careful
> optimization of the whole system for carefully selected routines
> (kernels of routines).
> 
> But this does not concern the compiler...
> 
> Krzystof, maybe, you can speed up your computations by using
> hand-optimized blas etc for Pentium. Or have a look at atlas or
> phipac.
> 
> Yours,
> Michael
> 
> 
> +---------------------------------------------------------------+
> |  Michael Hanke                Royal Institute of Technology   |
> |                               NADA                            |
> |                               S-10044 Stockholm               |
> |                               Sweden                          |
> +---------------------------------------------------------------+
> |  Visiting address:            Lindstedtsvaegen 3              |
> |  Phone:                       + (46) (8) 790 6278             |
> |  Fax:                         + (46) (8) 790 0930             |
> |  Email:                       hanke AT nada DOT kth DOT se               |
> |                               na DOT mhanke AT na-net DOT ornl DOT gov       |
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>