From octave-maintainers-request at bevo dot che dot wisc dot edu Thu Nov 21 00:56:26 2002
Subject: Re: Patching Octave-MPI
From: Paul Kienzle <pkienzle at jazz dot ncnr dot nist dot gov>
To: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
Cc: JD Cole <jdcole at san dot rr dot com>, octave-maintainers@bevo.che.wisc.edu
Date: Thu, 21 Nov 2002 01:55:44 -0500

There are a variety of approaches to parallelism which have been done
in matlab m-files and mex-files.  E.g.,

	http://supertech.lcs.mit.edu/~cly/survey.html

I'm a little surprised that you would need to patch octave itself to
do the same.

If you want fast parallel matrix operations, wouldn't you be better off
having an interface to scalapack or something similar?  Or are you
designing new parallel algorithms?  

Paul Kienzle
pkienzle at users dot sf dot net

On Wed, Nov 20, 2002 at 09:12:07PM -0600, John W. Eaton wrote:
> On 20-Nov-2002, JD Cole <jdcole at san dot rr dot com> wrote:
> 
> |    In the process of patching Andy's MPI support into octave, I have 
> | come across the following dilemma: Should I add additional make targets 
> | to config files such as Makeconf.in, like this:
> | + mpi%.o : mpi%.cc
> | +     $(CXX) -c $(CPPFLAGS) $(MPI_DEFS) $(MPI_CPPFLAGS) $(ALL_CXXFLAGS) 
> | $< -o $ at 
> | 
> | %.o : %.cc
> |     $(CXX) -c $(CPPFLAGS) $(ALL_CXXFLAGS) $< -o $ at 
> | 
> | or
> | 
> | keep with the original:
> | 
> | %.o : %.cc
> |     $(CXX) -c $(CPPFLAGS) $(ALL_CXXFLAGS) $< -o $ at 
> | 
> | and add MPI_CPPFLAGS to ALL_CXXFLAGS somewhere inbetween configure.in 
> | and Makeconf.in (I'm wondering if appending XTRA_CXXFLAGS would be 
> | appropriate for this?)
> 
> What are these MPI_* variables defined to be?  Are special things
> needed because of the way the MPI headers and libraries are installed
> on your system, or is it something that is always needed?
> 
> | I am partial to the latter solution because it reduces the amount of 
> | code duplication in the makefiles. As far as I could see adding MPI 
> | includes to the global includes with which octave is compiled shouldn't 
> | effect the end result. The situation may be slightly different if I were 
> | to add the MPI_LDFLAGS to ALL_LDFLAGS.
> 
> What would go in MPI_LDFLAGS?
> 
> | Any thoughts?
> 
> I've been assuming that we would add a configure option to enable
> MPI.  That would add whatever is necessary to the normal INCFLAGS,
> etc.
> 
> jwe
>