Unfortunately, this is a known issue.  :-\

I have not found a reliable way to deduce that MPI_IN_PLACE has been passed as 
the parameter to MPI_REDUCE (and friends) on OS X.  There's something very 
strange going on with regards to the Fortran compiler and common block 
variables (which is where we have MPI_IN_PLACE and other sentinel-value MPI 
constants defined).

We have a very old ticket open on this issue:

    https://svn.open-mpi.org/trac/ompi/ticket/1982

Any suggestions would be welcome.  :-\


On Nov 23, 2011, at 1:20 PM, Arjen van Elteren wrote:

> Dear All,
> 
> I'm running a complex program with a number of MPI_REDUCE calls, every call 
> uses MPI_IN_PLACE as the first parameter (the send buffer).
> 
> I'm currently testing this program on Mac 10.6 with macports installed.
> 
> Unfortunately all MPI_REDUCE calls with MPI_IN_PLACE, seem to fail. 
> 
> I've pinpointed the problem to the MPI_IN_PLACE parameter location, it seems 
> to matter if it is the first or the second parameter to the MPI_REDUCE call.
> 
> This is specific for fortran, in C the sequence does not matter!
> 
> A simple program to test this:
> 
> PROGRAM MAIN
>   implicit none
>   include 'mpif.h'
>   integer :: x(10)
>   integer :: provided,ioerror
>   call MPI_INIT(ioerror)
>   x = 1
> 
>   print *, x
>   call MPI_REDUCE(x, MPI_IN_PLACE,10, MPI_INTEGER, MPI_SUM, 0,MPI_COMM_WORLD, 
>  ioerror)
>   print *, x
>   call MPI_REDUCE(MPI_IN_PLACE, x,10, MPI_INTEGER, MPI_SUM, 0,MPI_COMM_WORLD, 
>  ioerror)
>   print *, x
> 
>   call MPI_FINALIZE(ioerror)
> END PROGRAM
> 
> I run this on one process (mpiexec ./a.out)
> 
> I'm running with openmpi version 1.5.4 (macports)
> 
> The openmpi is compiled with gfortran 4.4.6
> 
> Is this a bug in openmpi or is my understanding of MPI_REDUCE wrong?
> 
> Best regards,
> 
> Arjen
> _______________________________________________
> users mailing list
> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users


-- 
Jeff Squyres
jsquy...@cisco.com
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