SYNTAX¶

#include <mpi.h>
int MPI_Get_accumulate(const void *origin_addr, int origin_count,


    MPI_Datatype origin_datatype, void *result_addr,


    int result_count, MPI_Datatype result_datatype,


    int target_rank, MPI_Aint target_disp, int target_count,


    MPI_Datatype target_datatype, MPI_Op op, MPI_Win win)
int MPI_Rget_accumulate(const void *origin_addr, int origin_count,


    MPI_Datatype origin_datatype, void *result_addr,


    int result_count, MPI_Datatype result_datatype,


    int target_rank, MPI_Aint target_disp, int target_count,


    MPI_Datatype target_datatype, MPI_Op op, MPI_Win win,


    MPI_Request *request)

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_GET_ACCUMULATE(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, RESULT_ADDR,


        RESULT_COUNT, RESULT_DATATYPE, TARGET_RANK, TARGET_DISP, TARGET_COUNT,


        TARGET_DATATYPE, OP, WIN, IERROR)


    <type> ORIGIN_ADDR, RESULT_ADDR(*)


    INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP


    INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_COUNT, TARGET_DATATYPE,


        TARGET_RANK, TARGET_COUNT, TARGET_DATATYPE, OP, WIN, IERROR
MPI_RGET_ACCUMULATE(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, RESULT_ADDR,


        RESULT_COUNT, RESULT_DATATYPE, TARGET_RANK, TARGET_DISP, TARGET_COUNT,


        TARGET_DATATYPE, OP, WIN, REQUEST, IERROR)


    <type> ORIGIN_ADDR, RESULT_ADDR(*)


    INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP


    INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_COUNT, TARGET_DATATYPE,


        TARGET_RANK, TARGET_COUNT, TARGET_DATATYPE, OP, WIN, REQUEST, IERROR

USE mpi_f08
MPI_Get_accumulate(origin_addr, origin_count, origin_datatype, result_addr,


        result_count, result_datatype, target_rank, target_disp,


        target_count, target_datatype, op, win, ierror)


    TYPE(*), DIMENSION(..), INTENT(IN) :: origin_addr


    TYPE(*), DIMENSION(..) :: result_addr


    INTEGER, INTENT(IN) :: origin_count, result_count, target_rank, target_count


    TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype, result_datatype


    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_dist


    TYPE(MPI_Op), INTENT(IN) :: op


    TYPE(MPI_Win), INTENT(IN) :: win


    INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_Rget_accumulate(origin_addr, origin_count, origin_datatype,


        result_addr, result_count, result_datatype, target_rank,


        target_disp, target_count, target_datatype, op, win, request,


        ierror)


    TYPE(*), DIMENSION(..), INTENT(IN) :: origin_addr


    TYPE(*), DIMENSION(..) :: result_addr


    INTEGER, INTENT(IN) :: origin_count, result_count, target_rank, target_count


    TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype, result_datatype


    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_dist


    TYPE(MPI_Op), INTENT(IN) :: op


    TYPE(MPI_Win), INTENT(IN) :: win


    TYPE(MPI_Request), INTENT(OUT) :: request


    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS¶

OUTPUT PARAMETER¶

DESCRIPTION¶

MPI_Get_accumulate is a function used for one-sided MPI communication that adds the contents of the origin buffer (as defined by origin_addr, origin_count, and origin_datatype) to the buffer specified by the arguments target_count and target_datatype, at offset target_disp, in the target window specified by target_rank and win, using the operation op. MPI_Get_accumulate returns in the result buffer result_addr the contents of the target buffer before the accumulation.

Any of the predefined operations for MPI_Reduce, as well as MPI_NO_OP, can be used. User-defined functions cannot be used. For example, if op is MPI_SUM, each element of the origin buffer is added to the corresponding element in the target, replacing the former value in the target.

Each datatype argument must be a predefined data type or a derived data type, where all basic components are of the same predefined data type. Both datatype arguments must be constructed from the same predefined data type. The operation op applies to elements of that predefined type. The target_datatype argument must not specify overlapping entries, and the target buffer must fit in the target window.

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.

MPI_Rget_accumulate is similar to MPI_Get_accumulate, except that it allocates a communication request object and associates it with the request handle (the argument request) that can be used to wait or test for completion. The completion of an MPI_Rget_accumulate operation indicates that the data is available in the result buffer and the origin buffer is free to be updated. It does not indicate that the operation has been completed at the target window.

NOTES¶

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.

MPI_Get is a special case of MPI_Get_accumulate, with the operation MPI_NO_OP. Note, however, that MPI_Get and MPI_Get_accumulate have different constraints on concurrent updates.

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_Get_accumulate function.

ERRORS¶

Almost all MPI routines return an error value; C routines as the return result of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

MPI applications can also implement their own error handlers by calling:

Note that MPI does not guarantee that an MPI program can continue past an error.

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

SEE ALSO:

COPYRIGHT¶

2003-2024, The Open MPI Community