I figured it out. In the real application, I also did not have the 'use' statement, and there was an IMPLICIT statement causing the omp_get_max_threads() function to be automatically compiled as a real function instead of as integer, and the integers were automatically promoted to 8-byte using -i8.
Once I added the 'use omp_lib' statement, the compiler caught the mis-match. Just to verify, I did add the 'use omp_lib' statement and ran the test program by itself. I do get '4' as expected regardless of whether or not I run the program under MPI. So there is no OpenMPI-related issue. I thought it was OpenMPI-related because, after commenting out the MPI calls, I got the right answer. But this was probably just a coincidence. Thanks, Ed I did not have the 'use' statement. -----Original Message----- From: users-boun...@open-mpi.org [mailto:users-boun...@open-mpi.org] On Behalf Of Reuti Sent: Thursday, April 04, 2013 7:13 AM To: Open MPI Users Subject: Re: [OMPI users] Confused on simple MPI/OpenMP program Hi, Am 04.04.2013 um 04:35 schrieb Ed Blosch: > Consider this Fortran program snippet: > > program test use omp_lib include 'mpif.h' might be missing. > ! everybody except rank=0 exits. > call mpi_init(ierr) > call mpi_comm_rank(MPI_COMM_WORLD,irank,ierr) > if (irank /= 0) then > call mpi_finalize(ierr) > stop > endif > > ! rank 0 tries to set number of OpenMP threads to 4 call > omp_set_num_threads(4) nthreads = omp_get_max_threads() print*, > "nthreads = ", nthreads > > call mpi_finalize(ierr) > > end program test > > It is compiled like this: 'mpif90 -o test -O2 -openmp test.f90' > (Intel > 11.x) > > When I run it like this: mpirun -np 2 ./test > > The output is: "nthreads = 0" > > Does that make sense? I was expecting 4. > > If I comment out the MPI lines and run the program serially (but still > compiled with mpif90), then I get the expected output value 4. Nope, for me it's still 0 then. -- Reuti > I'm sure I must be overlooking something basic here. Please enlighten me. > Does this have anything to do with how I've configured OpenMPI? > > Thanks, > > Ed > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users
