PROGRAM main
use mpi
integer FILESIZE, MAX_BUFSIZE, INTSIZE
parameter (FILESIZE=1048576, MAX_BUFSIZE=1048576, INTSIZE=4)
integer buf(MAX_BUFSIZE), rank, ierr, fh, nprocs, nints
integer status(MPI_STATUS_SIZE), count
integer (kind=MPI_OFFSET_KIND) offset
call MPI_INIT(ierr)
call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
call MPI_COMM_SIZE(MPI_COMM_WORLD, nprocs, ierr)
call MPI_FILE_OPEN(MPI_COMM_WORLD, '/pfs/datafile', &
MPI_MODE_RDONLY, MPI_INFO_NULL, fh, ierr)
nints = FILESIZE/(nprocs*INTSIZE)
offset = rank * nints * INTSIZE
call MPI_FILE_READ_AT(fh, offset, buf, nints, MPI_INTEGER, &
status, ierr)
call MPI_GET_COUNT(status, MPI_INTEGER, count, ierr)
print *, 'process ', rank, 'read ', count, 'integers'
call MPI_FILE_CLOSE(fh, ierr)
call MPI_FINALIZE(ierr)
END PROGRAM main