Designing communication strategies for heterogeneous parallel systems

This paper investigates communication strategies for interconnecting heterogeneous parallel systems. As the speed of processors and parallel systems keep on increasing over the years, electronic interconnections like HIPPI and FDDI are reaching their limit to provide heterogeneous parallel computing environment. This paper explores the suitability of the emerging passive star-coupled optical interconnection using wavelength division multiplexing as the system interconnect to provide high bandwidth (Gbits/sec) communication demanded by heterogeneous systems. Several di erent communication strategies (combinations of communication topologies and protocols) over Wavelength Division Multiplexed (WDM) communication media like optic ber are investigated under a representative master-slave computational model. The interplay between system speed, network speed, task granularity, and degree of parallelism is studied using both analytical modeling and simulations. It is shown that a hierarchical ALOHA-based communication strategy between the master and the slaves, implemented on top of the passive star-coupled network, leads to a considerable reduction in channel contention and provides 50% 80% reduction in task completion time for applications with medium to high degrees of coarse grain parallelism. Comparable reduction in channel contention is also shown to be achieved by using tunable acoustooptic lters at master nodes.