-------- Message original -------- Sujet: Re: question: java Date : Wed, 02 Dec 2009 14:30:51 +0100 De : Tina ODAKA <Tina.Odaka@ifremer.fr> Organisation : IFREMER Pour : Eric Chatellier <chatellier@codelutin.com>, Benjamin Poussin <poussin@codelutin.com>, Jean Couteau <couteau@codelutin.com> Copie à : bpre@ifremer.fr <bpre@ifremer.fr>, Marc Simon <smarc@sgi.com>, COTTY <Pierre.Cotty@ifremer.fr>, aboudot@sgi.com, MAHEVAS <Stephanie.Mahevas@ifremer.fr> p.s. for your problem of that you can only use '2G'. i started to talk with colleagues from sgi so that you can 'write' on memory space, by using '/tmpfs' we did not do enough test yet on this subject, but once the tests are done, i will let you know where you can 'write' your matrix data you need but which exeed 2G so that you have to write on 'disk' regards, tina Tina ODAKA a écrit :
hello.
I went to see the people from intel what they think about your idia that C is faster on intel machine than java code.
they say, 10 years ago, may be it was true. but with their new SSE4.2 system and icc compiler (for 'c', or ifort compiler for fortran) now it is not true anymore, since with SSE you can for example multiple 4 values at a time, but with java compiler that is not possible.
regards, tina
Eric Chatellier a écrit :
Le 12/11/2009 09:49, Tina ODAKA a écrit :
hello eric jean benjamin, Hi,
Sorry for the long response delay :-(
i was talking with sgi about that your code is slow. they asked me one thing
JAVA : Ce language se base sur une machine virtuelle qui fait la génération des instruction à la volée. Les langages interprétés ne sont pas performant par définition. Il doit être possible de générer une version "compilée" du code Java qui doit apporter de meilleurs performances. i guess your code is 'version "compilée"', isn't it? IsisFish code is "pre-compiled" into java bytecode [1]. This bytecode is interpreted by the Java virtual machine at runtime.
Next, Java use JIT compilation [2], to improve runtime performance.
So, Java isn't slow, and run as fast as native compiled programs, or maybe even faster ;-)
tina [1] : http://en.wikipedia.org/wiki/Bytecode [2] : http://en.wikipedia.org/wiki/Just-in-time_compilation
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