MPI_Buffer_attach - Attaches a user-defined buffer for sending
int MPI_Buffer_attach(void *buf, int size)
buf - initial buffer address (choice)
size - buffer size, in bytes (integer)
The size given should be the sum of the sizes of all outstanding Bsends
that you intend to have, plus a few hundred 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( 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;
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).
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
If an error occurs in an MPI function, the current MPI error handler is
called to handle it. 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 (in C and Fortran; this error handler is less
useful in with the C++ MPI bindings. The predefined error handler
MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
needs to be recovered). Note that MPI does not guarantee that an MPI
program can continue past an error.
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. The C++ bindings for MPI do not return error
values; instead, error values are communicated by throwing exceptions
of type MPI::Exception (but not by default). Exceptions are only
thrown if the error value is not MPI::SUCCESS .
Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
functions will return upon an error, there will be no way to recover
what the actual error value was.
- No error; MPI routine completed successfully.
- Invalid buffer pointer. Usually a null buffer where one is
- An internal error has been detected. This is fatal. Please
send a bug report to the LAM mailing list (see http://www.lam-
For more information, please see the official MPI Forum web site, which
contains the text of both the MPI-1 and MPI-2 standards. These
documents contain detailed information about each MPI function (most of
which is not duplicated in these man pages).
The LAM Team would like the thank the MPICH Team for the handy program
to generate man pages ("doctext" from
ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz ), the initial
formatting, and some initial text for most of the MPI-1 man pages.