Effect of Hot Spot on the Performance of Multistage Interconnection Networks

Hot spot in multistage interconnection networks (MSIN) results in performance degradation of the network. This paper develops an analytical model for the performance evaluation of unbuffered MSINs under a single hot spot, followed by a performance comparison with buffered MSINs. A hybrid network is proposed for optimum performance. 1 Introduction An interconnection network connects processors to memory modules in a shared-memory multiprocessor system. Because of modularity, simplicity, and faulttolerant capabilities of crossbar and multiple-bus interconnections, such interconnections requiring O(N 2 ) switches have been widely investigated. MSIN reduces the number of switches required to O(N log N ). Buffers may be used at the switches to increase the throughput and avoid internal loss of data. However, in the case of a hot spot, the throughput of a buffered system is significantly reduced due to a phenomenon called tree saturation [1]. Most of the previous work have dealt with unif..