Torus Ring: improving performance of interconnection network by modifying hierarchical ring

Abstract

In multiprocessor systems, interconnection network design is critical for overall system performance. Among the popular interconnection networks, unidirectional ring-based networks have been one of popular choices for high performance large-scale shared memory multiprocessor systems. In this paper, we propose “Torus Ring”, which is a modified version of two-level hierarchical ring. The Torus Ring has the same complexity as the hierarchical rings, and the only difference is the way it connects the local rings. Compared to hierarchical rings, the Torus Ring helps exploit the memory access locality of application programs more efficiently. It has an advantage over the hierarchical ring when the destination of a packet is the adjacent local ring, especially the backward adjacent local ring. Although we assume that the destination of a network packet is uniformly distributed across the processing nodes, the average number of hops in Torus Ring is equal to that of the hierarchical ring. However, the performance gain of the Torus Ring is expected to increase, due to the memory access locality of the application programs in the real parallel programming environment. In the simulation results, the latency of the interconnection network is reduced by up to 19% and the execution time is reduced by up to 10%, with the moderate ring utilization ratio.