An Evaluation of Planar - Adaptive Routing ( PAR ) 1

Network performance can be improved by allowing adaptive routing, but doing so introduces new possibilities of deadlock which can overwhelm the exibility advantages. Planar-adaptive routing (PAR) resolves this tension by limiting adaptive routing to a series of two-dimensional planes, reducing hardware requirements for deadlock prevention. We explore the performance of planar-adaptive routers for two, three, and four-dimensional networks. Under non-uniform traac loads, the planar-adaptive router signiicantly outperforms the dimension-order router, while giving comparable performance under uniform loads. With equal resources, the planar-adaptive router provides superior performance to fully-adaptive routers because it requires less resources for deadlock prevention, freeing resources to increase the number of virtual lanes.