Design of Bandwidth Aware and Congestion Avoiding Efficient Routing Algorithms for Networks-on-Chip Platforms

In this paper we demonstrate that it is possible to design highly efficient application specific routing algorithms which distribute traffic more uniformly by using information regarding applications communication behavior (communication topology and communication bandwidth). We use off-line analysis to estimate expected load on various links in the network. The result of this analysis is used along with the available routing adaptivity in each router to distribute less traffic to links and paths which are expected to be congested. The methodology for Application Specific Routing Algorithms (APSRA) is extended to incorporate these features to design highly adaptive deadlock free routing algorithms which also distribute traffic more uniformly and reduce network congestion. We show that the number of congested links (links exceeding threshold bandwidth) is reduced by up to 100% with this extension. Significant reduction in average delay is also obtained for both synthetic (up to 25%) as well as a real application (12.5%) communication traffic with this extension to APSRA. We discuss architectural implications and area overhead of our approach on the design of a table based NoC router.