Rout3D: A lightweight adaptive routing algorithm for tolerating faulty vertical links in 3D-NoCs

Abstract

3D integration opens up new opportunities for future multiprocessor chips by enabling fast and highly scalable 3D Network-on-Chip (NoC) topologies. However, in an aim to reduce the cost of Through-silicon via (TSV), partially vertically connected NoCs, in which only a few vertical TSV links are available, have been gaining relevance. In addition, the number of vertical paths can be expected to be further reduced due to defects and runtime failures. To reliably route packets under such conditions, we introduce a lightweight, efficient and highly resilient adaptive routing algorithm targeting partially vertically connected 3D-NoCs named “Rout3D”. It requires a very low number of virtual channels (VCs) to achieve deadlock-freedom (2 VCs in the East and North directions and 1 VC in all other directions), and guarantees packet delivery as long as one healthy TSV connecting all layers is available anywhere in the network. We combine our algorithm with a novel offline reconfiguration method requiring only 4 bits per router to maintain connectivity upon the occurrence of faults while minimizing the implementation cost. Simulation results reveal that our algorithm is capable of sustaining a very good level of performance compared to related works, in spite of using less virtual channels.