|
« Return to documentation listing
Table of Contents
MPI_Fetch_and_op - Combines the contents of the origin buffer
with that of a target buffer and returns the target buffer value.
#include <mpi.h>
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)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_FETCH_AND_OP(ORIGIN_ADDR, RESULT_ADDR, DATATYPE, TARGET_RANK,
TARGET_DISP, OP, WIN, IERROR)
<type> ORIGIN_ADDR, RESULT_ADDR(*)
INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP
INTEGER DATATYPE, TARGET_RANK, OP, WIN, IERROR
USE mpi_f08
MPI_Fetch_and_op(origin_addr, result_addr, datatype, target_rank,
target_disp, op, win, ierror)
TYPE(*), DIMENSION(..), INTENT(IN) :: origin_addr
TYPE(*), DIMENSION(..) :: result_addr
TYPE(MPI_Datatype), INTENT(IN) :: datatype
INTEGER, INTENT(IN) :: target_rank
INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_disp
TYPE(MPI_Op), INTENET(IN) :: op
TYPE(MPI_Win), INTENT(IN) :: win
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- origin_addr
- Initial address of buffer (choice).
- result_addr
- Initial address of result buffer (choice).
- datatype
- Data type 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 (nonnegative integer).
- op
- Reduce operation (handle).
- win
- Window object (handle).
- IERROR
- Fortran only: Error
status (integer).
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 contents of the target
buffer before the accumulation.
The origin and result buffers (origin_addr
and result_addr) must be disjoint. Any of the predefined operations for
MPI_Rreduce, 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. The operation is executed atomically.
A new predefined operation,
MPI_REPLACE, is defined. It corresponds to the associative function f(a,
b) =b; that is, the current value in the target memory is replaced by the
value supplied by the origin.
A new predefined operation, MPI_NO_OP, is
defined. It corresponds to the assiciative function f(a, b) = a; that is
the current value in the target memory is returned in the result buffer
at the origin and no operation is performed on the target buffer.
The MPI standard prescribes portable Fortran syntax for the TARGET_DISP
argument only for Fortran 90. FORTRAN 77 users may use the non-portable
syntax
INTEGER*MPI_ADDRESS_KIND TARGET_DISP
where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length
of the declared integer in bytes.
It is the user’s responsibility to
guarantee that, when using the accumulate functions, the target displacement
argument is such that accesses to the window are properly aligned according
to the data type arguments in the call to the MPI_Fetch_and_op function.
Almost all MPI routines return an error value; C routines as the
value of the function and Fortran routines in the last argument.
Before
the error value is returned, the current MPI error handler is called. By
default, this error handler aborts the MPI job, except for I/O function
errors. The error handler may be changed with MPI_Comm_set_errhandler; 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.
MPI_Get_accumulate
MPI_Reduce
Table of Contents
« Return to documentation listing
|
