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MPI_Buffer_attach(3) man page (version 1.2.9)

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NAME

       MPI_Buffer_attach - Attaches a user-defined buffer for sending.

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Buffer_attach(void *buf, int size)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_BUFFER_ATTACH(BUF, SIZE, IERROR)
            <type>    BUF(*)
            INTEGER   SIZE, IERROR

C++ Syntax

       #include <mpi.h>
       void Attach_buffer(void* buffer, int size)

INPUT PARAMETERS

       buf       Initial buffer address (choice).

       size      Buffer size, in bytes (integer).

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       Provides  to MPI a buffer in the user's memory to be used for buffering
       outgoing messages. The buffer is used only by messages sent in buffered
       mode. Only one buffer can be attached to a process at a time.

NOTES

       The size given should be the sum of the sizes of all outstanding Bsends
       that you intend to have, plus MPI_BSEND_OVERHEAD bytes 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( buf, 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;

       MPI_BSEND_OVERHEAD gives the maximum amount of buffer space that may be
       used by the Bsend routines. This value is in mpi.h for C and mpif.h for
       will be used to throw an MPI:Exception object.

       Before  the  error  value is returned, the current MPI error handler is
       called. By default, this error handler aborts the MPI job,  except  for
       I/O   function   errors.   The   error  handler  may  be  changed  with
       MPI_Comm_set_errhandler; 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.

SEE ALSO

       MPI_Buffer_detach

Open MPI 1.2                    September 2006     MPI_Buffer_attach(3OpenMPI)

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