CirKet: A Performance Efficient Hybrid Switching Mechanism for NoC Architectures

Abstract

In this paper, we propose and evaluate a hybrid switching mechanism for Network-on-Chips (NoCs). We propose the use of pseudo circuit-switching along with packet-switching in NoC routers. To do this, packets traversing NoC channels are categorized into high and low priority packets which are routed using pseudo circuit and packet switching respectively. Each output port of NoC routers are equipped with a one-bit flag register indicating that the traversing packet is either of low or high priority packet. Using pseudo circuit switching, high priority packets reserve the intermediate routers till the tail flit passes the router. The proposed switching mechanism offers its highest efficiency for applications in which the traffic is dominated by streams. We have used Booksim2 which is a cycle accurate NoC simulator to evaluate the proposed switching technique. Results show that the proposed switching mechanism 1) offers at least 10% improvement in overall flit latency in all tested scenarios as compared with a packet-switched NoC, 2) reduces the power dissipation in the router logic by at least 4%, and 3) imposes a negligible area overhead to NoC router circuitry.