MPIBufferattach(3OpenMPI) MPIBufferattach(3OpenMPI)

NAME
       MMPPIIBBuuffffeerraattttaacchh - Attaches a user-defined buffer for sending.


SSYYNNTTAAXX
CC SSyynnttaaxx
       #include 
       int MPIBufferattach(void *buf, int size)


FFoorrttrraann SSyynnttaaxx
       INCLUDE 'mpif.h'
       MPIBUFFERATTACH(BUF, SIZE, IERROR)
                BUF(*)
            INTEGER   SIZE, IERROR


CC++++ SSyynnttaaxx
       #include 
       void Attachbuffer(void* buffer, int size)


IINNPPUUTT PPAARRAAMMEETTEERRSS
       buf       Initial buffer address (choice).

       size      Buffer size, in bytes (integer).


OOUUTTPPUUTT PPAARRAAMMEETTEERR
       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.


NNOOTTEESS
       The size given should be the sum of the sizes of all outstanding Bsends
       that you intend to have, plus MPIBSENDOVERHEAD bytes for  each  Bsend
       that  you  do.  For  the  purposes  of calculating size, you should use
       MPIPacksize. In other words, in the code

           MPIBufferattach( buf, size );
           MPIBsend( ..., count=20, datatype=type1, ... );
           ...
           MPIBsend( ..., count=40, datatype=type2, ... );

       the value of size in the MPIBufferattach call should be greater  than
       the value computed by

           MPIPacksize( 20, type1, comm, &s1 );
           MPIPacksize( 40, type2, comm, &s2 );
           size = s1 + s2 + 2 * MPIBSENDOVERHEAD;

       MPIBSENDOVERHEAD 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
       Fortran.


EERRRROORRSS
       Almost  all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last  argument.  C++  func-
       tions  do  not  return  errors.  If the default error handler is set to
       MPI::ERRORSTHROWEXCEPTIONS, then on error the C++ exception mechanism
       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
       MPICommseterrhandler; the predefined error handler MPIERRORSRETURN
       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
       MPIBufferdetach




Open MPI 1.2                    September 2006     MPIBufferattach(3OpenMPI)