EFFICIENT MULTICAST ON WORMHOLE SWITCH-BASED NOWP

High bandwidth and low latency switches are commercially available. Us ing these switches, it becomes possible to build a system area network to interconnect workstations and processor clusters together to provi de a cost-effective parallel computing platform. A processor cluster m ay be a shared-memory multiprocessor or a mesh-connected multicomputer , etc. The interconnection topology on this kind of platform, called s witch-based NOWP, is usually irregular. On such systems, multicast is an important collective communication operation. Two steps are involve d in a multicast: (1) the source node sends the multicast message to t he destinations which are connected to a switch directly or are the le ader of a processor cluster, and (2) the leader node of each cluster s ends the message to other destinations in the same cluster. In this pa per, we propose two unicast-based multicast algorithms. Algorithm Mult icast_1 performs those two steps sequentially; while Algorithm Multica st_2 overlaps them. Performance of the two algorithms will be evaluate d and compared.