NAME¶
MPI_Fetch_and_op - Perform one-sided read-modify-write.
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)
Accumulate one element of type datatype from the origin buffer (origin_addr) to
the buffer at offset target_disp, in the target window specified by
target_rank and win, using the operation op and return in the result buffer
result_addr the content of the target buffer before the accumulation.
- origin_addr
- - initial address of buffer (choice)
- result_addr
- - initial address of result buffer (choice)
- datatype
- - datatype of the entry in origin, result, and target buffers
(handle)
- target_rank
- - rank of target (nonnegative integer)
- target_disp
- - displacement from start of window to beginning of target buffer
(non-negative integer)
- op
- - reduce operation (handle)
- win
- - window object (handle)
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 guarentee 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_ARG
- - Invalid argument. Some argument is invalid and is not identified by a
specific error class (e.g., MPI_ERR_RANK ).
- MPI_ERR_COUNT
- - Invalid count argument. Count arguments must be non-negative; a count of
zero is often valid.
- 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. May be an uncommitted MPI_Datatype (see
MPI_Type_commit ).
- MPI_ERR_WIN
- - Invalid MPI window object
SEE ALSO¶
MPI_Get_accumulate
LOCATION¶
/tmp/gyCYfBi4J6/mpich-3.1/src/mpi/rma/fetch_and_op.c