MPI_IBSEND, MPI_Ibsend

Purpose

Performs a nonblocking buffered mode send operation.

C synopsis

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

C++ synopsis

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

FORTRAN synopsis

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

Description

MPI_IBSEND starts a buffered mode, nonblocking send. The send buffer may
not be modified until the request has been completed by MPI_WAIT, MPI_TEST,
or one of the other MPI wait or test functions.

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 the destination task in comm (integer) (IN)
tag
     is the message tag (positive integer) (IN)
comm
     is the communicator (handle) (IN)
request
     is the communication request (handle) (OUT)
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_IBSEND_OVERHEAD*number_of_messages) should be
sufficient.

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

Errors

Invalid count
     count < 0

Invalid datatype

Invalid destination

Type not committed
     dest < 0 or dest > = groupsize

Invalid tag
     tag < 0

Invalid comm

MPI not initialized

MPI already finalized

Develop mode error if:

Illegal buffer update

Related information

     MPI_BSEND
     MPI_BSEND_INIT
     MPI_BUFFER_ATTACH
     MPI_WAIT