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Abstract
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Nonuniform traffic patterns can severely degrade the performance of wormhole-routing mesh networks in multiprocessor systems. For example, under a temporary hot-spot traffic, a saturation tree might build up temporarily within the network resulting in a temporary network overload that will delay messages substantially. To the knowledge of the authors, no mechanisms were proposed in the open literature so far that are able to control (rather than just route) the traffic flow under those traffic scenarios. This paper introduces and studies several channel assignment strategies for wormhole routers using virtual channels. It is shown that one assignment strategy (empty-first, variable assignment; EV), is able to effectively control the degrading effects of saturation trees on the uniform background traffic under nonuniform traffic patterns that are known a priori. It can minimize the length of the hot-spot phase, or, alternatively, suppress any saturation trees and network overloads under temporary nonuniform traffic scenarios, while it does not degrade performance under pure uniform traffic patterns. Performance characteristics in-between those two extreme cases can be achieved as well. Also, the EV router outperforms conventional wormhole routers in almost all cases. To account for different application needs, an adaptive assignment strategy is introduced as well.
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Reference entry
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Keck, D.O.; Jurczyk, M.
Traffic Control in Wormhole Routing Meshes under Non-Uniform Traffic Patterns
Proceedings of the 11th IASTED International Conference on Parallel and Distributed Computing and Systems, Cambridge, MA, November 1999, pp. 302-133-1-302-133-6
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