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Subject: Re: [OMPI users] GCC extendability to OpenMPI Specification
From: Joe Landman (landman_at_[hidden])
Date: 2008-06-04 03:58:17

Mukesh K Srivastava wrote:
> Hi OMPI Community.
> Is there any thought process to extend GCC support to OpenMPI or
> implementation of OpenMPI specification in GCC for C, C++ & Fortran and
> making it generally available for platforms which supports POSIX.

Hi Mukesh:

   Open MPI is already written in C, and compiles correctly under
several different GCC flavors. It works with C, C++, and Fortran90
currently, on multiple POSIX platforms.

   Are you asking about including this natively with GCC? As OpenMP is
integrated into the compiler?

   Please remember that MPI is generally a set of function/method calls
that implement particular operations. Even with a system as "simple" as
OpenMP (not Open MPI), automatic parallelization in the general quite
hard (and you don't get great performance). MPI does force you to think
about communication topology as well as many other issues. It would be
great if the compiler could handle this for you, but unfortunately, it
is far more than a "simple matter of programming". This is a genuinely
hard problem.

> Can GCC community think extending a support library for OpenMPI in it's
> releases.

   You can build the lib*.so for each compiler, but please remember that
the builds can be different (just look at all those nice options in
configure!). The API should be the same, so as long as you build
against the same version (Jeff and others, please correct me if this
assumption is not correct), you should be able to move your runtime
linked binaries around.

> BR
> Mukesh


Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman_at_[hidden]
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