if (rank != root) {
/* recv from parent on non-root */
Request::recv(ptmp, rcount * size, rdtype, bmtree->tree_prev, COLL_TAG_SCATTER, comm, &status);
if (rank != root) {
/* recv from parent on non-root */
Request::recv(ptmp, rcount * size, rdtype, bmtree->tree_prev, COLL_TAG_SCATTER, comm, &status);