[mpich-discuss] gfortran and mpich2 interaction

[jdelia at intec.unl.edu.ar]

Dear developers,

 From the first distributions of the GFORTRAN compiler (experimental  
or not), I had noticed a little execution problem (of low impact) when  
the attached test program runs in parallel using MPICH2. I ignore if  
it is a problem of GFORTRAN or MPICH2 but it does not happen neither   
with G95 nor with IFORT.

As a  simple test (please, see at the end of this message), the  
processor 0 must read a variable "n" that is entered by console.  
During the execution (including the case with a single  process), it  
does not print any message until a value is entered for the required  
variable.

In the present test I used the current 1.0.7 stable version of MPICH2  
(http://www.mcs.anl.gov/research/projects/mpich2/downloads/index.php?s=downloads)

$ which mpif90
/usr/local/mpich2-exp/1.0.7/bin/mpif90

$ mpif90 --version
GNU Fortran (GCC) 4.4.0 20080302 (experimental) [trunk revision 132813]
Copyright (C) 2007 Free Software Foundation, Inc.

GNU Fortran comes with NO WARRANTY, to the extent permitted by law.
You may redistribute copies of GNU Fortran
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING

$ mpif90 -Wall -std=f2003 -fPIC -o testinputmpi.exe testinputmpi.f90

$ mpiexec -machinefile ~/machi.dat -np 1 testinputmpi.exe
100
100
100
    matrix rank ; n : ?
    matrix rank ; n =          100
    matrix rank ; n : ?
    matrix rank ; n =          100
    matrix rank ; n : ?
    matrix rank ; n =          100

$ cat /proc/version
Linux version 2.6.9-22.0.1.ELsmp (root at yort.fnal.gov) (gcc version  
3.4.3 20050227 (Red Hat 3.4.3-22.1)) #1 SMP Thu Oct 27 10:53:36 CDT 2005

The nodes of our Beowulf cluster are 32-bit processors (i386, Intel  
Pentium 4).

Perhaps, if this problem is in the way that the program is compiled or  
the MPICH2 was built (please, see config.log.gz attached file), is  
there some compilation or building flag for fix this little trouble ?

Thanks in advance,

Regards,
Jorge.

! -----------------------------------------------------------------
! MPICH2
!  which mpif90
!  mpif90 --version
!  mpif90 -Wall -std=f2003 -fPIC -o testinputmpi.exe testinputmpi.f90
!  mpdboot -n 5 -f ~/mpd.hosts
!  mpdtrace
!  mpdringtest
!  mpiexec -machinefile ~/machi.dat -np 2 testinputmpi.exe
!  mpdallexit
!
! -----------------------------------------------------------------
program testinputmpi
    use mpi
    implicit none
    integer :: myid, siza, ierr, master=0, n
    !
    call MPI_Init (ierr)
    call MPI_Comm_size (MPI_COMM_WORLD, siza, ierr) ! number of processes
    call MPI_Comm_rank (MPI_COMM_WORLD, myid, ierr) ! my rank
    !
    if (myid == master) then
      ! alternative 1
      write (*,*)
      write (*,*) " matrix rank ; n : ? "
      read  (*,*) n
      write (*,*) " matrix rank ; n = ", n
      ! alternative 2
      write (6,*)
      write (6,*) " matrix rank ; n : ? "
      read  (5,*) n
      write (6,*) " matrix rank ; n = ", n
      ! alternative 3
      print  *
      print  *,   " matrix rank ; n : ? "
      read  (*,*) n
      print  *,   " matrix rank ; n = ", n
    else
      write (*,*) "hellow from ", myid, " of ", siza, "processes"
    end if
    !
    call MPI_Finalize (ierr)
    !
end program
! -------------------------------------------------------------------

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