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Date:      Sun, 5 Jan 2003 14:25:56 -0500
From:      Rahul Siddharthan <rsidd@online.fr>
To:        Brett Glass <brett@lariat.org>
Cc:        Terry Lambert <tlambert2@mindspring.com>, Greg 'groggy' Lehey <grog@FreeBSD.org>, chat@FreeBSD.org
Subject:   Re: Bystander shot by a spam filter
Message-ID:  <20030105192556.GA526@papagena.rockefeller.edu>
In-Reply-To: <4.3.2.7.2.20030105120224.029377d0@localhost>
References:  <3E18073C.68182FE4@mindspring.com> <4.3.2.7.2.20030104201251.029387d0@localhost> <4.3.2.7.2.20030104112015.026a5530@localhost> <4.3.2.7.2.20030104201251.029387d0@localhost> <4.3.2.7.2.20030104202908.03c3b100@localhost> <20030105073804.GA72674@wantadilla.lemis.com> <20030105074923.GA4956@papagena.rockefeller.edu> <3E18073C.68182FE4@mindspring.com> <4.3.2.7.2.20030105120224.029377d0@localhost>

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Brett Glass said on Jan  5, 2003 at 12:03:36:
> At 06:34 AM 1/5/2003, Rahul Siddharthan wrote:
> 
> >The point is, sparse matrix operations and LU decomposition are
> >exactly the cases Brett is talking about.
> 
> Our primary interest wasn't sparse matrix operations. 

You did say you were interested in heavily nested loops and floating
point arithmetic.  Sparse matrix operations qualify.

It is interesting, in fact, that gcc does well in all such problems.
It doesn't do very well in Gauss-Siedel relaxation (which is a fairly
straightforward iterative method) and does quite badly in a
monte-carlo integration (which is basically just one long loop with
calls to a random number generator and the function evaluator).  

Again, gcc does well on the mazebench and Stepanov benchmarks,
and badly on the rather meaningless Whetstone benchmark.

Perhaps Intel produces better "straight" code than gcc -- not
surprising if it's their chip -- but gcc actually does better
optimization, and therefore catches up on more complex code?

- Rahul

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