Turn grouping for multicast in wormhole-routed mesh networks supporting the turn model

Multicast is an important collective communication in scalable parallel computers. One efficient scheme to perform multicast is multidestination messaging[8]. In multidestination messaging, destination nodes of a multicast are partitioned into disjoint groups. Nodes in each group are reached with a multidestination message that conforms to the base routing algorithm of the system. A systematic way of partitioning the nodes is critical to the efficiency of multidestination messaging. In this paper we propose a node grouping method, called turn grouping, for partitioning the destination nodes in a multicast. Turn grouping is general in the sense that it supports any base routing algorithm derivable from the turn model [5]. Given such a base routing algorithm and the corresponding prohibited turns, turn grouping can systematically produce a proper schedule for multicasting the message. We evaluated the performance of turn grouping using three typical turn model-based routing algorithms. The simulation results show that our approach performs better than the Umesh [12] and the Hamiltonian-path [8] algorithms.