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Re: multi-threaded octave?

From: Paul Kienzle
Subject: Re: multi-threaded octave?
Date: Tue, 14 Jan 2003 22:10:28 -0500
User-agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.2.1) Gecko/20021130

Shahbaz Chaudhary wrote:

Hi, I just installed Octave and it works great.  But as I was running a
particularly long computation, I noticed that it was only using one of
my cpus (my computer has two).  Apparently it is single
there a multi-threaded version of the program?


Actually I installed octave (and every thing it depended on) using
redhat RPMs (for my RH 7.3) system.  Later I found out about
ATLAS...while I was installing that it asked my about multiple threads.
Once I had configured and installed atlas, I ran my octave session
again, but didn't see any difference...I'm not sure if that is because
my pre-existing octave didn't even pickup the newly installed atlas.

If you are not seeing any performance gain on matrix multiplication for larger matrices (e.g., x=rand(100); tic; y=x*x; toc) then you aren't linking against atlas. You may need
to reconfigure and recompile octave from sources.

Any way, if there is something I can do to improve performance
(especially since one of my cpus is going to waste), I'll appreciate it.

Serial code will be slow. Try to get rid of for loops whereever they occur. Make sure you preallocate matrices rather than extending them. Once you have your algorithm developed,
convert the remaining for loops into C++.

BTW, if I run octave on Apple's g4...will their vector technology
significantly speed up octave?  Thanks.

If you have vendor blas which can make use of it then it may. Altas is competitive with
vendor blas in a lot of cases, so you may see no gain.

Paul Kienzle

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