mp_sum_rm3 Subroutine

      SUBROUTINE mp_sum_rm3(msg, gid)
      !! Element-wise sum of a rank-3 array on all processes.
      !! @note see mp_sum_r

         REAL(kind=real_4), CONTIGUOUS, INTENT(INOUT)     :: msg(:, :, :)
         !! Array to sum and result
         TYPE(mp_comm_type), INTENT(IN)                      :: gid

         CHARACTER(LEN=*), PARAMETER :: routineN = 'mp_sum_rm3'

         INTEGER                                  :: handle, ierr, &
                                                     msglen
         ierr = 0
         CALL timeset(routineN, handle)

         msglen = SIZE(msg)
#if defined(__parallel)
         IF (msglen > 0) THEN
            CALL mpi_allreduce(MPI_IN_PLACE, msg, msglen, MPI_REAL, MPI_SUM, gid%handle, ierr)
            IF (ierr /= 0) CALL mp_stop(ierr, "mpi_allreduce @ "//routineN)
         END IF
         CALL add_perf(perf_id=3, msg_size=msglen*real_4_size)
#else
         MARK_USED(gid)
#endif
         CALL timestop(handle)
      END SUBROUTINE mp_sum_rm3