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From: Christophe TROESTLER <debian00@tiscali.be>
To: "O'Caml Mailing List" <caml-list@inria.fr>
Subject: NBody (one more question)
Date: Thu, 24 Feb 2005 23:18:55 +0100 (CET)	[thread overview]
Message-ID: <20050224.231855.40627447.debian00@tiscali.be> (raw)
In-Reply-To: <20050208104312.GA10035@yquem.inria.fr>

Hi,

I'd like to come back to the nbody mini-benchmark with one more
question (I apologize if I bother some people but I think there are
competent people here who can clarify the situation for me).

When I compile the C code with -O0 (with gcc -o nbody.gcc -Wall
--fast-math nbody.c -lm), I get a time of 1.513s which is comparable
to OCaml (1.607s).  But as soon as I turn on -O options (as with gcc
-o nbody.gcc -Wall -O1 --fast-math nbody.c -lm), the running time
drops down to 0.871s (0.58%).  Can somebody tell me what is the
optimization that has such an effect and whether it could be applied
to OCaml ?  (I am not saying or asking it to be done -- it is not up
to me to decide -- I just want to understand -- and I am not versed
enough in assembly to do it myself unfortunately :( ).

Regards,
ChriS


  parent reply	other threads:[~2005-02-25 13:01 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-07 18:57 [Benchmark] NBody Christophe TROESTLER
2005-02-07 19:16 ` [Caml-list] " Will M. Farr
2005-02-07 19:36   ` Christophe TROESTLER
2005-02-07 19:55     ` Will M. Farr
2005-02-08 10:34       ` Olivier Andrieu
2005-02-08 10:52         ` Micha
2005-02-07 20:16     ` Markus Mottl
2005-02-07 19:37 ` Martin Jambon
2005-02-07 19:46   ` Christophe TROESTLER
2005-02-07 20:22     ` Martin Jambon
2005-02-07 20:04   ` sejourne_kevin
2005-02-07 20:32     ` Robert Roessler
2005-02-07 22:57     ` Oliver Bandel
2005-02-08  1:29 ` skaller
2005-02-08  1:48   ` Will M. Farr
2005-02-08  9:01     ` Ville-Pertti Keinonen
2005-02-08  9:37     ` skaller
2005-02-08 10:10       ` Ville-Pertti Keinonen
2005-02-08 16:36         ` skaller
2005-02-08 12:04       ` Marcin 'Qrczak' Kowalczyk
2005-02-08 17:06         ` skaller
2005-02-08 10:25   ` Xavier Leroy
2005-02-08 18:34     ` skaller
2005-02-08 10:43 ` Xavier Leroy
2005-02-08 11:26   ` Ville-Pertti Keinonen
2005-02-08 15:59   ` Florian Hars
2005-02-13 16:40   ` Christoph Bauer
2005-02-13 18:13   ` Christophe TROESTLER
2005-02-24 22:18   ` Christophe TROESTLER [this message]
2005-02-25 17:06     ` [Caml-list] NBody (one more question) John Carr
2005-02-25 17:17       ` Christophe TROESTLER
2005-02-26 16:08         ` John Carr
2005-02-25 17:24     ` Ken Rose
2005-02-25 17:42       ` Oliver Bandel
2005-02-25 17:57     ` Xavier Leroy

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