Coupling Routing Algorithm and Data Encoding for Low Power Networks on Chip

Abstract

The routing algorithm used in a Network-on-Chip (NoC) has a strong impact on both the functional and non functional indices of the overall system. Traditionally, routing algorithms have been designed considering performance and cost as the main objectives. In this study we focus on two important non functional metrics, namely, power dissipation and energy consumption. We propose a selection policy that can be coupled with any multi-path routing function and whose primary goal is reducing power dissipation. As technology shrinks, the power dissipated by the network links represents an ever more significant fraction of the total power budget. Based on this, the proposed selection policy tries to reduce link power dissipation by selecting the output port of the router which minimises the switching activity of the output link. A set of experiments carried out on both synthetic and real traffic scenarios is presented. When the proposed selection policy is used in conjunction with a data encoding technique, on average, 31% of energy reduction and 37% of power saving is observed. An architectural implementation of the selection policy is also presented and its impact on cost (silicon area) and power dissipation of the baseline router is discussed.