3D NOC for many-core processors

With an increasing number of processors forming many-core chip multiprocessors (CMP), there exists a need for easily scalable, high-performance and low-power intra-chip communication infrastructure for emerging systems. In CMPs with hundreds of processing elements, 3D integration can be utilized to shorten long wires forming communication links. In this paper, we propose a Clos network-on-chip (CNOC) in conjunction with 3D integration as a viable network topology for many core CMPs. The primary benefit of 3D CNOC is scalability and a clear upper bound on power dissipation. We present the architectural and physical design of 3D CNOC and compare its performance with several other topologies. Comparisons are made among several topologies (fat tree, flattened butterfly, mesh and Clos) showing the power consumption of a 3D CNOC increases only minimally as the network size is scaled from 64 to 512 nodes relative to the other topologies. Furthermore, in a 512-node system, 3D CNOC consumes about 15% less average power than any other topology. We also compare 3D partitioning strategies for these topologies and discuss their effect on wire delay and the number of through-silicon vias.