56. Communication Initiation


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We use the same naming conventions as for blocking communication: a prefix of B, S, or R is used for buffered, synchronous or ready mode. In addition a prefix of I (for immediate) indicates that the call is nonblocking.

MPI_ISEND(buf, count, datatype, dest, tag, comm, request)
IN bufinitial address of send buffer (choice)
IN countnumber of elements in send buffer (non-negative integer)
IN datatypedatatype of each send buffer element (handle)
IN destrank of destination (integer)
IN tagmessage tag (integer)
IN commcommunicator (handle)
OUT requestcommunication request (handle)

int MPI_Isend(void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm, MPI_Request *request)

MPI_ISEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR
MPI::Request MPI::Comm::Isend(const void* buf, int count, const MPI::Datatype& datatype, int dest, int tag) const
Start a standard mode, nonblocking send.

MPI_IBSEND(buf, count, datatype, dest, tag, comm, request)
IN bufinitial address of send buffer (choice)
IN countnumber of elements in send buffer (non-negative integer)
IN datatypedatatype of each send buffer element (handle)
IN destrank of destination (integer)
IN tagmessage tag (integer)
IN commcommunicator (handle)
OUT requestcommunication request (handle)

int MPI_Ibsend(void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm, MPI_Request *request)

MPI_IBSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR
MPI::Request MPI::Comm::Ibsend(const void* buf, int count, const MPI::Datatype& datatype, int dest, int tag) const
Start a buffered mode, nonblocking send.

MPI_ISSEND(buf, count, datatype, dest, tag, comm, request)
IN bufinitial address of send buffer (choice)
IN countnumber of elements in send buffer (non-negative integer)
IN datatypedatatype of each send buffer element (handle)
IN destrank of destination (integer)
IN tagmessage tag (integer)
IN commcommunicator (handle)
OUT requestcommunication request (handle)

int MPI_Issend(void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm, MPI_Request *request)

MPI_ISSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR
MPI::Request MPI::Comm::Issend(const void* buf, int count, const MPI::Datatype& datatype, int dest, int tag) const
Start a synchronous mode, nonblocking send.

MPI_IRSEND(buf, count, datatype, dest, tag, comm, request)
IN bufinitial address of send buffer (choice)
IN countnumber of elements in send buffer (non-negative integer)
IN datatypedatatype of each send buffer element (handle)
IN destrank of destination (integer)
IN tagmessage tag (integer)
IN commcommunicator (handle)
OUT requestcommunication request (handle)

int MPI_Irsend(void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm, MPI_Request *request)

MPI_IRSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR
MPI::Request MPI::Comm::Irsend(const void* buf, int count, const MPI::Datatype& datatype, int dest, int tag) const
Start a ready mode nonblocking send.

MPI_IRECV (buf, count, datatype, source, tag, comm, request)
OUT bufinitial address of receive buffer (choice)
IN countnumber of elements in receive buffer (non-negative integer)
IN datatypedatatype of each receive buffer element (handle)
IN sourcerank of source (integer)
IN tagmessage tag (integer)
IN commcommunicator (handle)
OUT requestcommunication request (handle)

int MPI_Irecv(void* buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm, MPI_Request *request)

MPI_IRECV(BUF, COUNT, DATATYPE, SOURCE, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, SOURCE, TAG, COMM, REQUEST, IERROR
MPI::Request MPI::Comm::Irecv(void* buf, int count, const MPI::Datatype& datatype, int source, int tag) const
Start a nonblocking receive.

These calls allocate a communication request object and associate it with the request handle (the argument request). The request can be used later to query the status of the communication or wait for its completion.

A nonblocking send call indicates that the system may start copying data out of the send buffer. The sender should not access any part of the send buffer after a nonblocking send operation is called, until the send completes.

A nonblocking receive call indicates that the system may start writing data into the receive buffer. The receiver should not access any part of the receive buffer after a nonblocking receive operation is called, until the receive completes.


Advice to users.

To prevent problems with the argument copying and register optimization done by Fortran compilers, please note the hints in subsections ``Problems Due to Data Copying and Sequence Association,'' and ``A Problem with Register Optimization'' in Section Problems With Fortran Bindings for MPI on pages Problems Due to Data Copying and Sequence Association and A Problem with Register Optimization . ( End of advice to users.)



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