Performance evaluation of fully adaptive wormhole routing including selection function choice

Many adaptive routing algorithms have been proposed for wormhole-routed interconnection networks. Comparatively little work, however, has been done on determining how the selection function affects the performance of an adaptive routing algorithm. In this paper, we present a detailed simulation study of various selection functions for four different fully adaptive wormhole routing algorithms for 2D meshes. The simulation results show that the choice of selection function has a significant effect on the average message latency and saturation behavior. In fact, it appears that changing the selection function can have a greater effect than changing the routing algorithm. In addition, the best selection function for one adaptive routing algorithm may not be the best choice for another adaptive routing algorithm. An explanation and interpretation of the results is provided.