基于动态注入率的片上网络拥塞避免方法

片上网络的拥塞现象极大地限制了路由器的有效性能，拥塞问题将直接影响到整个处理器芯片的性能.本文首先分析了片上网络中虚通道路由器通信流量的特性．提出设定不同的阈值将网络拥塞状态进行划分，将拥塞避免问题划分为拥塞预防和拥塞解除两个阶段．提出使用一种动态注入率策略，根据实时检测网络的拥塞状态，动态调整网络报文的注入率，将网络中的通信流量控制在一个合理水平内，减轻网络的负载压力，避免NoC完全陷入拥塞而出现瘫痪状态．仿真模拟结果表明，拥塞预防时NoC性能约在“最大负载点”，拥塞解除时性能约在“膝点”，注入率可以达到0.05，在避免拥塞的同时有效兼顾了网络性能.

Dynamic Injecting Strategy for Congestion Avoidance for NoC

Network-on-chip congestion greatly limits the effective performance of the router, and directly affects the performance of the processor chip. This paper divided the network's congestion state by using different threshold, and set the congestion avoidance apart into two distinct phases: congestion prevention and congestion relieving. Then a dynamic injection strategy was proposed. According to the congestion state in real-time, packet injection rate was adjusted dynamically, and communication traffic was controlled in reasonable level to decrease load press, avoiding congestion effectively. The simulation result shows that the performance of congestion prevention is almost at "Cliff" point, while congestion relieving is almost at "Knee" point, the injection rate can reach 0.05, and network performance is tradeoff with congestion avoidance.