#include "mpi.h" int MPI_Buffer_attach( buffer, size ) void *buffer; int size;
the value of size in the MPI_Buffer_attach call should be greater than the value computed by
MPI_Buffer_attach( buffer, size ); MPI_Bsend( ..., count=20, datatype=type1, ... ); ... MPI_Bsend( ..., count=40, datatype=type2, ... );
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).
MPI_Pack_size( 20, type1, comm, &s1 ); MPI_Pack_size( 40, type2, comm, &s2 ); size = s1 + s2 + 2 * MPI_BSEND_OVERHEAD;
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran.
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_Errhandler_set; 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.