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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)

       int MPI_Buffer_attach_c(void *buffer, MPI_Count size)

INPUT PARAMETERS
       buffer -	initial	buffer address (choice)
       size   -	buffer size, in	bytes (non-negative 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 guarantee 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_ARG
	      -	Invalid	argument.  Some	argument is invalid and	is not identi-
	      fied by a	specific error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_OTHER
	      -	 Other	error;	use  MPI_Error_string  to get more information
	      about this error code.

SEE ALSO
       MPI_Buffer_detach, MPI_Bsend

				   2/3/2025		  MPI_Buffer_attach(3)

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