MPI_Win_start function

Starts an RMA access epoch for MPI window.

Syntax

int MPIAPI MPI_Win_start(
   MPI_Group group,
   int       assert,
   MPI_Win   win
);

Parameters

• group
  Group of target processes.

• assert
  Used to optimize this call; zero may be used as a default.

• win
  Window object.

Return value

Returns MPI_SUCCESS on success. Otherwise, the return value is an error code.

In Fortran, the return value is stored in the IERROR parameter.

Fortran

    MPI_WIN_START(GROUP, ASSERT, WIN, IERROR)
        INTEGER GROUP, ASSERT, WIN, IERROR

Remarks

The assert argument is used to indicate special conditions for the fence that an implementation may use to optimize the MPI_Win_start operation. The value zero is always correct. Other assertion values may be or''ed together. Assertions tha are valid for MPI_Win_start are:

• MPI_MODE_NOCHECK - the matching calls to MPI_Win_post have already completed on all target processes when the call to MPI_Win_start is made. The nocheck option can be specified in a start call if and only if it is specified in each matching post call. This is similar to the optimization of ready-send that may save a handshake when the handshake is implicit in the code. (However, ready-send is matched by a regular receive, whereas both start and post must specify the nocheck option.)

Requirements

See also

MPI One-Sided Communications Functions