GLIO_GROUP(3F)					      Last changed: 2-24-98

NAME    [Toc]    [Back]

     glio_group_mpi, glio_group_shmem -	Defines	a group	of processes to	be
     associated	with a global file.

SYNOPSIS    [Toc]    [Back]

     C or C++:

	  #include <ffio.h>
	  #include <mpi.h>
	  void glio_group_mpi(MPI_Comm comm)
	  #include <mpp/shmem.h>
	  void glio_group_shmem(int handle);

     Fortran:

	  include "mpif.h"
	  INTEGER comm
	  CALL GLIO_GROUP_MPI(comm)
	  include "mpp/shmem.fh"
	  INTEGER handle
	  CALL GLIO_GROUP_SHMEM(handle);

IMPLEMENTATION    [Toc]    [Back]

     UNICOS/mk and IRIX	systems

DESCRIPTION    [Toc]    [Back]

     These subroutines identify	the group of processes which will share
     access to any FFIO	files opened with the global FFIO layer.  These
     files, termed global files, must be opened	and closed collectively	by
     all processes that	share access to	them.

     The following is a	list of	valid arguments	for these routines:

     comm      An MPI communicator. The	group of processes associated with
	       this communicator will access the global	file.  This process
	       group must be executing within a	single host machine.

     handle    A SHMEM process group handle returned from the
	       shmem_group_create_strided() function.

     The glio_group_mpi	and glio_group_shmem functions are collective
     across the	set of processes identified by comm or handle.

     If	glio_group_mpi or glio_group_shmem are not called prior	to an open
     of	a global file, all MPI or SHMEM	processes in the application must
     collectively open and close the file.

EXAMPLES    [Toc]    [Back]

     The following Fortran program opens global	file globfile for access
     from SHMEM	processes (PEs)	0 and 1.  PEs 2	and higher will	not access
     the file.

	  program global_subset
	  include "mpp/shmem.fh"
	  integer racom, handle
	  common /racom/ racom(SHMEM_GROUP_COM_SIZE)

	  call start_pes(0)
	  racom	= 0

     c	  Define a SHMEM group and then	open globfile across this group

	  if (my_pe().le.1) then
	    call assign("assign	-F global u:20",ier)
	    handle = shmem_group_create_strided(0, 1, 2, racom,	shmem_null)
	    call glio_group_shmem(handle)
	    open (20,file="globfile",access="direct",recl=64)
	  endif

	  end

SEE ALSO    [Toc]    [Back]

     shmem_group_create_strided(3)

     Application Programmer's Library Reference	Manual,	publication
     SR-2165, for the printed version of this man page.