|buf||Initial buffer address (choice).|
Buffer size, in bytes (integer).
IERROR Fortran only: Error status (integer).
Provides to MPI a buffer in the users 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.
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 Fortran.
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, 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 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.
|1.10.2||MPI_BUFFER_ATTACH (3)||Jan 21, 2016|