Synopsis

int MPI_Fetch_and_op(const void *origin_addr, void *result_addr,
                     MPI_Datatype datatype, int target_rank,
                     MPI_Aint target_disp, MPI_Op op, MPI_Win win)

Input Parameters

origin_addr

initial address of buffer (choice)

datatype

datatype of the entry in origin, result, and target buffers (handle)

target_rank

rank of target (non-negative integer)

target_disp

displacement from start of window to beginning of target buffer (non-negative integer)

op

reduce operation (handle)

win

window object (handle)

Output Parameters

result_addr

initial address of result buffer (choice)

Notes

This operations is atomic with respect to other "accumulate" operations.

The generic functionality of MPI_Get_accumulate might limit the performance of fetch-and-increment or fetch-and-add calls that might be supported by special hardware operations. MPI_Fetch_and_op thus allows for a fast implementation of a commonly used subset of the functionality of MPI_Get_accumulate.

The origin and result buffers (origin_addr and result_addr) must be disjoint. Any of the predefined operations for MPI_Reduce, as well as MPI_NO_OP or MPI_REPLACE, can be specified as op; user-defined functions cannot be used. The datatype argument must be a predefined datatype.

Notes for Fortran

All MPI routines in Fortran (except for 'MPI_WTIME' and 'MPI_WTICK') have an additional argument 'ierr' at the end of the argument list. 'ierr' is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the 'call' statement.

All MPI objects (e.g., 'MPI_Datatype', 'MPI_Comm') are of type 'INTEGER' in Fortran.

Errors

All MPI routines (except 'MPI_Wtime' and 'MPI_Wtick') return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with 'MPI_Comm_set_errhandler' (for communicators), 'MPI_File_set_errhandler' (for files), and 'MPI_Win_set_errhandler' (for RMA windows). The MPI-1 routine 'MPI_Errhandler_set' may be used but its use is deprecated. The predefined error handler 'MPI_ERRORS_RETURN' may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

  • MPI_SUCCESS - No error; MPI routine completed successfully.

  • MPI_ERR_DISP - Invalid displacement argument

  • MPI_ERR_OP - Invalid operation. MPI operations (objects of type 'MPI_Op') must either be one of the predefined operations (e.g., 'MPI_SUM') or created with 'MPI_Op_create'.

  • MPI_ERR_RANK - Invalid source or destination rank. Ranks must be between zero and the size of the communicator minus one; ranks in a receive ('MPI_Recv', 'MPI_Irecv', 'MPI_Sendrecv', etc.) may also be 'MPI_ANY_SOURCE'.

  • MPI_ERR_TYPE - Invalid datatype argument. Additionally, this error can occur if an uncommitted MPI_Datatype (see 'MPI_Type_commit') is used in a communication call.

  • MPI_ERR_WIN - Invalid MPI window object

  • MPI_ERR_OTHER - Other error; use 'MPI_Error_string' to get more information about this error code.

See also

MPI_Get_accumulate(3)