Newsgroups: comp.parallel.mpi,comp.parallel.pvm
From: Erlend.Helmersen@math.sintef.no
Subject: Use MPI and PVM simultaneously, possible?
Keywords: pvm, mpi, simultaneous, heterogeneous
Organization: University of Tromsoe, Norway
Date: 21 Oct 1996 17:52:45 GMT
Message-ID: <54gd9d$jsp@news.uit.no>

-- 

Hi, all!

This may seem like a strange question to some of you, but bare with me.
My question is based on the following problem:

Given: a running simulator code that run on some machine (eg. IBM SP2,
       or maybe just a cluster of workstations). This code use MPI for
       message passing. I cannot (will not) change this code.

Need:  To be able to (dynamically) connect and disconnect to
       this simulator from another (arbitrary) machine, and
       preferably be able to communicate with each node
       directly. I cannot assume that this other process is able to run
       and stay connected trough the whole run of the simulator (it can be
       a week or more). This other process is supposed to monitor and possibly
       change parameters in the simulator. The communication takes place
       trough a library that currently use TCP for message transfer. Given
       that many parallel machines does not have TCP on all nodes we need
       something else.

Problem: In MPI one cannot dynamically add and delete tasks after MPI_INIT
         is called. I cannot use MPI for my problem.

Solution?: Use PVM in additon to MPI and in this way be able to dynamically
           add new processes to the program.

Finally the question: Can one use PVM *AND* MPI in the same program? MPI
        Will only be used between the nodes in the parallel machine, while
        PVM will be used to communicate with one machine outside the 
        machine (or group of machines) that MPI originally ran on.
        I just dont know if there will be any problems, or if I test
        it for machines X and Y and find that it works OK, does this
        meen that it will always work or are there implementation specific
        problems that lurk in the background?

        Anybody has some experience with something similar?

When MPI 2 comes everything will be *SO* much easier......


Erlend

--
Erlend.Helmersen@math.sintef.no (PGP) // Research Scientist // 73596843/96623451

