NAME¶
MPI_Buffer_attach - Attaches a user-defined buffer for sending
SYNOPSIS¶
#include <mpi.h>
int MPI_Buffer_attach(void *buf, int size)
- buf
- - initial buffer address (choice)
- size
- - buffer size, in bytes (integer)
NOTES¶
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 Fortran.
ERRORS¶
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.
- MPI_SUCCESS
- - No error; MPI routine completed successfully.
- MPI_ERR_BUFFER
- - Invalid buffer pointer. Usually a null buffer where one is not
valid.
- MPI_ERR_INTERN
- - An internal error has been detected. This is fatal. Please send a bug
report to the LAM mailing list (see
http://www.lam-mpi.org/contact.php ).
SEE ALSO¶
MPI_Buffer_detach, MPI_Bsend
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).
http://www.mpi-forum.org/
ACKNOWLEDGEMENTS¶
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.
LOCATION¶
bufattach.c