Message: 4
Date: Mon, 27 Jul 2009 17:13:23 -0400
From: George Bosilca <bosilca@eecs.utk.edu>
Subject: Re: [OMPI users] MPI_IN_PLACE in Fortran with MPI_REDUCE /
MPI_ALLREDUCE
To: Open MPI Users <users@open-mpi.org>
Message-ID: <966A51C3-A15F-425B-A6B0-81221033CCF1@eecs.utk.edu>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes

Ricardo,

I can't reproduce your problem with the latest version (trunk r21734).  
If I run the provided program on two nodes I get the following answer.
[***]$ mpif77 inplace.f -o inplace -g
[***]$ mpirun -bynode -np 2 ./inplace
 Result:
   3.0000000       3.0000000       3.0000000       3.0000000

This seems correct and in sync with the C answer.

  george.


On Jul 27, 2009, at 09:42 , Ricardo Fonseca wrote:

program inplace

 use mpi

 implicit none

 integer :: ierr, rank, rsize, bsize

 real, dimension( 2, 2 ) :: buffer, out

 integer :: rc

 call MPI_INIT(ierr)

 call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)

 call MPI_COMM_SIZE(MPI_COMM_WORLD, rsize, ierr)

 buffer = rank + 1

 bsize = size(buffer,1) * size(buffer,2)

 if ( rank == 0 ) then

   call mpi_reduce( MPI_IN_PLACE, buffer, bsize, MPI_REAL, MPI_SUM,  

0, MPI_COMM_WORLD, ierr )

 else

   call mpi_reduce( buffer,       0,      bsize, MPI_REAL, MPI_SUM,  

0, MPI_COMM_WORLD, ierr )

 endif

 ! use allreduce instead

 ! call mpi_allreduce( MPI_IN_PLACE, buffer, bsize, MPI_REAL,  

MPI_SUM, MPI_COMM_WORLD, ierr )

 if ( rank == 0 ) then

   print *, 'Result:'

   print *, buffer

 endif

 rc = 0

 call mpi_finalize( rc )

end program