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Subject: [OMPI users] MPI_Allreduce on local machine
From: Hugo Gagnon (sourceforge.openmpi_at_[hidden])
Date: 2010-07-26 23:06:02


Hello,

When I compile and run this code snippet:

  1 program test
  2
  3 use mpi
  4
  5 implicit none
  6
  7 integer :: ierr, nproc, myrank
  8 integer, parameter :: dp = kind(1.d0)
  9 real(kind=dp) :: inside(5), outside(5)
 10
 11 call mpi_init(ierr)
 12 call mpi_comm_size(mpi_comm_world, nproc, ierr)
 13 call mpi_comm_rank(mpi_comm_world, myrank, ierr)
 14
 15 inside = (/ 1, 2, 3, 4, 5 /)
 16 call mpi_allreduce(inside, outside, 5, mpi_double_precision,
 mpi_sum, mpi_comm_world, ierr)
 17
 18 print*, myrank, inside
 19 print*, outside
 20
 21 call mpi_finalize(ierr)
 22
 23 end program test

I get the following error, with say 2 processors:

forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image PC Routine Line
Source
libmpi.0.dylib 00000001001BB4B7 Unknown Unknown
Unknown
libmpi_f77.0.dyli 00000001000AF046 Unknown Unknown
Unknown
a.out 0000000100000CE2 _MAIN__ 16
test.f90
a.out 0000000100000BDC Unknown Unknown
Unknown
a.out 0000000100000B74 Unknown Unknown
Unknown
forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image PC Routine Line
Source
libmpi.0.dylib 00000001001BB4B7 Unknown Unknown
Unknown
libmpi_f77.0.dyli 00000001000AF046 Unknown Unknown
Unknown
a.out 0000000100000CE2 _MAIN__ 16
test.f90
a.out 0000000100000BDC Unknown Unknown
Unknown
a.out 0000000100000B74 Unknown Unknown
Unknown

on my iMac having compiled OpenMPI with ifort according to:
http://software.intel.com/en-us/articles/performance-tools-for-software-developers-building-open-mpi-with-the-intel-compilers/

Note that the above code snippet runs fine on my school parallel cluster
where ifort+intelmpi is installed.
Is there something special about OpenMPI's MPI_Allreduce function call
that I should be aware of?

Thanks,

-- 
  Hugo Gagnon