Hi, I have a question: Is the following combination of accumulate operations allowed and is this the "same operation" ? Process A and Process B perform a MPI_SUM operation on the same address in the same window with same predefined datatype but using different RMA function calls: Process A: MPI_Get_accumulate (..., target_rank, 0, 1, MPI_LONG_LONG_INT, MPI_SUM, win) Process B: MPI_Fetch_and_op(..., MPI_LONG_LONG_INT, target_rank, 0, MPI_SUM, win) If the answer is yes, I can't see the advantage of MPI_Fetch_and_op ("might support special hardware operations which use is limited by the generic functionality of MPI_Get_accumulate") since these special hardware operations have to be used by all accumulate functions in the same way (also for very large counts and derived datatypes). Many thanks in advance Hubert