MPI_Win_allocate_shared function

Creates an MPI Window object that allocates memory, allocated memory can be accessed from all processes in the window’s group with direct load/store instructions.

Syntax

int MPIAPI MPI_Win_allocate_shared(
        MPI_Aint size,
        int      disp_unit,
        MPI_Info info,
        MPI_Comm comm,
  _Out_ void     *baseptr,
  _Out_ MPI_Win  *win
);

Parameters

• size
  Size of the memory window in bytes.

• disp_unit
  Local unit size for displacements, in bytes.

• info
  Info argument.

• comm
  Intra-communicator.

• baseptr [out]
  Address of local allocated window segment.

• win [out]
  Window object returned by the call.

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_ALLOCATE_SHARED(SIZE, DISP_UNIT, INFO, COMM, BASEPTR, WIN, IERROR)
        <type> BASEPTR(*)
        INTEGER(KIND=MPI_ADDRESS_KIND) SIZE
        INTEGER DISP_UNIT, INFO, COMM, WIN, IERROR

Remarks

This is a collective call executed by all processes in the group of comm. On each process, it allocates memory of at least size bytes that is shared among all processes in comm, and returns a pointer to the locally allocated segment in baseptr that can be used for load/store accesses on the calling process. The locally allocated memory can be the target of load/store accesses by remote processes; the base pointers for other processes can be queried using the function MPI_Win_shared_query. The call also returns a window object that can be used by all processes in comm to perform RMA operations. The size argument may be different at each process and size = 0 is valid. It is the user’s responsibility to ensure that the communicator comm represents a group of processes that can create a shared memory segment that can be accessed by all processes in the group.

Requirements

See also

MPI One-Sided Communications Functions