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Paper   IPM / Computer Science / 10922
School of Computer Science
  Title:   A new general method to compute virtual channels occupancy probabilities in wormhole networks
  Author(s): 
1.  N. Alzeidi
2.  M. Ould-Khaoua
3.  A. Khonsari
  Status:   Published
  Journal: Journal of Computer and System Sciences
  No.:  6
  Vol.:  74
  Year:  2007
  Pages:   1033-1042
  Publisher(s):   Academic Press
  Supported by:  IPM
  Abstract:
Virtual channels have been proposed to develop deadlock free routing algorithms and to overcome the performance degradation due to chains of blocked messages in wormhole switched networks. Hence, capturing the effect of virtual channels has always been an important issue in developing analytical performance models for these interconnection networks. Almost all previous models relayed on a method proposed by Dally to compute the probability of the number of busy virtual channels per physical channel. Dallys method is based on a Markov chain and after extensive investigation our results reveal that its accuracy degrades as traffic increases. In this study we propose and validate a new general method to compute this probability. The new general method is based on an M/G/1 queue and it exhibits a good degree of accuracy at different traffic conditions. We further showed that Dallys method can be deduced as a special case of the general method. Predictions from both, Dallys method and the new general method are validated against results obtained from an event-driven simulator that mimics the behaviour of wormhole-switch networks.

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