A novel distributed congestion control for bufferless network-on-chip

Abstract

Bufferless Network-on-Chip (NoC) emerges as an interesting option for NoC design in recent years, which can save considerable router power and area. However, bufferless NoC only works well under low-to-medium load because it becomes more easily congested as message injection rate increases. In this paper, we propose a novel distributed source-throttling congestion control mechanism that relieves the effect of congestion in bufferless NoC under high load, called Cbufferless. The proposed strategy uses a novel congestion detection and control mechanism, computing average deflection rate of routing flit and distributed throttling message injection. Utilizing the new mechanism, the congestion information can be directly obtained inside node, which allows the mechanism to be fully distributed without requiring any transmission of global congestion information among neighbor routers and within a router. Simulation results show that the proposed mechanism improves system throughput by up to $$\sim $$ ~ 30 and $$\sim $$ ~ 15.5 %, saves energy consumption by up to $$\sim $$ ~ 40 and $$\sim $$ ~ 19 % than that of baseline and injection rate throttling bufferless NoCs, respectively, and keeps lower message latency under congested load when compared.