is_commutative    168 ompi/mca/coll/base/coll_base_reduce_scatter_block.c     int is_commutative = ompi_op_is_commute(op);
is_commutative    261 ompi/mca/coll/base/coll_base_reduce_scatter_block.c             if (is_commutative || (remote_tree_root < cur_tree_root)) {