Communication Delay in Wormhole-Switched Tori Networks under Bursty Workloads

Workloads generated by the real-world parallel applications that are executed on a multicomputer have a strong effect on the performance of its interconnection network—the hardware fabric supporting communication among individual processors. Existing multicomputer networks have been primarily designed and analysed under the assumption that the workload follows the non-bursty Poisson arrival process. As a step towards obtaining a clear understanding of network performance under various workloads, this paper presents a new analytical model for computing message latency in wormhole switched torus networks in the presence of bursty traffic, based on the well-known Markov-Modulated Poisson Process (MMPP). In order to derive the model, the approach for accurately capturing the properties of the composite MMPPs is applied to characterize traffic on network channels. Moreover, a general method has been proposed for calculating the probability of virtual channel occupancy when the traffic on network channels follows a multi-state MMPP process. Simulation experiments reveal that the model exhibits a good degree of accuracy.