MPI_BSEND, MPI_Bsend

Purpose

Performs a blocking buffered mode send operation.

C synopsis

#include <mpi.h>
int MPI_Bsend(void* buf,int count,MPI_Datatype datatype,
              int dest,int tag,MPI_Comm comm);

C++ synopsis

#include mpi.h
void MPI::Comm::Bsend(const void* buf, int count, const MPI::Datatype& datatype,
                      int dest, int tag) const;

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_BSEND(CHOICE BUF,INTEGER COUNT,INTEGER DATATYPE,INTEGER DEST,
          INTEGER TAG,INTEGER COMM,INTEGER IERROR)

Description

This subroutine is a blocking buffered mode send operation. It is a local
operation. It does not depend on the occurrence of a matching receive in
order to complete. If a send operation is started and no matching receive
is posted, the outgoing message is buffered to allow the send call to
complete.

Return from an MPI_BSEND does not guarantee the message was sent. It may
remain in the buffer until a matching receive is posted. MPI_BUFFER_DETACH
will block until all messages are received.

Parameters

buf
     is the initial address of the send buffer (choice) (IN)
count
     is the number of elements in the send buffer (integer) (IN)
datatype
     is the datatype of each send buffer element (handle) (IN)
dest
     is the rank of destination (integer) (IN)
tag
     is the message tag (positive integer) (IN)
comm
     is the communicator (handle) (IN)
IERROR
     is the FORTRAN return code. It is always the last argument.

Notes

Make sure you have enough buffer space available. An error occurs if the
message must be buffered and there is there is not enough buffer space. The
amount of buffer space needed to be safe depends on the expected peak of
pending messages. The sum of the sizes of all of the pending messages at
that point plus (MPI_BSEND_OVERHEAD*number_of_messages) should be
sufficient.

Avoid using MPI_BSEND if possible. It adds overhead because it requires an
extra memory-to-memory copy of the outgoing data. If MPI_BSEND is used, the
associated receive operations may perform better with MPI_CSS_INTERRUPT
enabled.

Errors

Invalid count
     count < 0

Invalid datatype

Type not committed

Invalid destination
     dest < 0 or dest > = groupsize

Invalid tag
     tag < 0

Invalid comm

Insufficient buffer space

MPI not initialized

MPI already finalized

Related information

     MPI_BUFFER_ATTACH
     MPI_BUFFER_DETACH
     MPI_IBSEND
     MPI_SEND