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MPI_Buffer_attach(3)		      MPI		  MPI_Buffer_attach(3)

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 com-
       municators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_er-
       rhandler	(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	 when-
       ever 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

LOCATION
       src/mpi/pt2pt/bufattach.c

				   9/20/2012		  MPI_Buffer_attach(3)

NAME | SYNOPSIS | INPUT PARAMETERS | NOTES | THREAD AND INTERRUPT SAFETY | NOTES FOR FORTRAN | ERRORS | SEE ALSO | LOCATION

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