From octave-maintainers-request at bevo dot che dot wisc dot edu Thu Nov 21 11:30:02 2002
Subject: Re: Patching Octave-MPI
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: octave-maintainers mailing list <octave-maintainers at bevo dot che dot wisc dot edu>
Date: Thu, 21 Nov 2002 11:30:00 -0600

On 21-Nov-2002, Paul Kienzle <pkienzle at jazz dot ncnr dot nist dot gov> wrote:

| I don't know anything about the details of distributed matrix libraries.
| In particular, I don't know how they decide if and when to distribute
| data.  
| 
| As a high level language, I would like octave to do the right thing.
| 
| If that means calling the local blas for small matrices and the parallel
| blas for large matrices, then Octave would have to be linked against
| both simultaneously.  If on the other hand the parallel blas are half
| way intelligent and don't distribute small computations across the net,
| there is no reason to link to the local blas.  If the user is really
| concerned, then link two different executables: poctave against the
| parallel blas and octave against the serial blas.

If the distributed matrix libraries don't do the right thing, then I
suppose one could always write a wrapper that does, though it would be
uglier if the distributed library uses the same names as the standard
one.  But in any case, what I was proposing would make it somewhat
easier to experiment.  And also somewhat easier to move an Octave
binary from one machine to another when using ATLAS or other tuned
blas/lapack libraries, because you wouldn't have to rely on dynamic
linker tricks.  You could just set an option saying what version of
the libraries you want to use.  This also makes it easier to
demonstrate the speedup for a given version of the libraries.  So I
think it is worth doing for these reasons, but I wanted to know if
anyone sees something that I'm missing.  Are there any reasons that it
would not be worth the effort?

jwe