NAME

       MPI_Buffer_attach -  Attaches a user-provided buffer for sending

SYNOPSIS

       int MPI_Buffer_attach(void *buffer, int size)

INPUT PARAMETERS

       buffer - initial buffer address (choice)
       size   - buffer size, in bytes (integer)

NOTES

       The size given should be the sum of the sizes of all outstanding Bsends that you intend to
       have, plus MPI_BSEND_OVERHEAD for each Bsend that you do.  For the purposes of calculating
       size, you should use MPI_Pack_size .

       In other words, in the code
       MPI_Buffer_attach( buffer, size );
       MPI_Bsend( ..., count=20, datatype=type1,  ... );
       .
       .
       .
       MPI_Bsend( ..., count=40, datatype=type2, ... );

       the  value of size in the MPI_Buffer_attach call should be greater than the value computed
       by
       MPI_Pack_size( 20, type1, comm, &s1 );
       MPI_Pack_size( 40, type2, comm, &s2 );
       size = s1 + s2 + 2 * MPI_BSEND_OVERHEAD;

       The MPI_BSEND_OVERHEAD gives the maximum amount of space that may be used  in  the  buffer
       for  use  by  the  BSEND routines in using the buffer.  This value is in mpi.h (for C) and
       mpif.h (for Fortran).

THREAD AND INTERRUPT SAFETY

       The user is responsible for ensuring that multiple threads do not try to update  the  same
       MPI  object  from different threads.  This routine should not be used from within a signal
       handler.

       The MPI standard defined a thread-safe interface but this does not mean that all  routines
       may  be  called  without  any  thread locks.  For example, two threads must not attempt to
       change the contents of the same MPI_Info object concurrently.  The user is responsible  in
       this  case  for using some mechanism, such as thread locks, to ensure that only one thread
       at a time makes use of this  routine.   Because  the  buffer  for  buffered  sends  (e.g.,
       MPI_Bsend  )  is  shared by all threads in a process, the user is responsible for ensuring
       that only one thread at a time calls this routine or MPI_Buffer_detach .

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME  and  MPI_WTICK  )  have  an  additional
       argument  ierr  at  the  end  of  the  argument list.  ierr is an integer and has the same
       meaning as the  return  value  of  the  routine  in  C.   In  Fortran,  MPI  routines  are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI  routines  (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as
       the value of the function and Fortran routines in the last argument.  Before the value  is
       returned,  the current MPI error handler is called.  By default, this error handler aborts
       the MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler  (for
       communicators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_errhandler (for RMA
       windows).  The MPI-1 routine MPI_Errhandler_set may be used but  its  use  is  deprecated.
       The  predefined  error  handler  MPI_ERRORS_RETURN may be used to cause error values to be
       returned.  Note that MPI does not guarentee that an  MPI  program  can  continue  past  an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_BUFFER
              - Invalid buffer pointer.  Usually a null buffer where one is not valid.
       MPI_ERR_INTERN
              - An internal error has been detected.  This is fatal.  Please send a bug report to
              mpi-bugs@mcs.anl.gov .

SEE ALSO

       MPI_Buffer_detach, MPI_Bsend

                                            11/12/2016                       MPI_Buffer_attach(3)