58. 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(const 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(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count, dest, tag
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_ISEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

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(const 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(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count, dest, tag
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_IBSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

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(const 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(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count, dest, tag
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_ISSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

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(const 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(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count, dest, tag
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_IRSEND(BUF, COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, DEST, TAG, COMM, REQUEST, IERROR

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 or MPI_ANY_SOURCE (integer)
IN tagmessage tag or MPI_ANY_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(*), DIMENSION(..), ASYNCHRONOUS :: buf
INTEGER, INTENT(IN) :: count, source, tag
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_IRECV(BUF, COUNT, DATATYPE, SOURCE, TAG, COMM, REQUEST, IERROR)
<type> BUF(*)
INTEGER COUNT, DATATYPE, SOURCE, TAG, COMM, REQUEST, IERROR

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 modify 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 Sections Problems With Fortran Bindings for MPI --Comparison with C . ( End of advice to users.)


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