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Subject: Re: [OMPI users] MPI_Bcast issue
From: Richard Treumann (treumann_at_[hidden])
Date: 2010-08-11 09:34:17


Randolf

I am confused about using multiple, concurrent mpirun operations. If
there are M uses of mpirun and each starts N tasks (carried out under pvm
or any other way) I would expect you to have M completely independent MPI
jobs with N tasks (processes) each. You could have some root in each of
the M MPI jobs do an MPI_Bcast to the other N-1) in that job but there is
no way in MPI (without using accept.connect) to get tasks of job 0 to give
data to tasks of jobs 1-(m-1).

With M uses of mpirun, you have M worlds that are forever isolated from
the other M-1 worlds (again, unless you do accept/connect)

In what sense are you treating this as an single MxN application? ( I
use M & N to keep them distinct. I assume if M == N, we have your case)

Dick Treumann - MPI Team
IBM Systems & Technology Group
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363