Floodgate: application-driven flow control in network-on-chip for many-core architectures

With the prevalence of multi- and many-core architecture, network-on-chip (NoC) is becoming the main paradigm for on-chip interconnection. However, the performance of NoCs can be degraded significantly if the network flow is not controlled properly. Most previous solutions have tried to detect network congestion by monitoring the hardware status of the network switches or links. Unfortunately, such strategies rely on the backpressure of the traffic flows for congestion detection and may be too slow to respond. This paper proposes a proactive strategy which predicts the global, end-to-end traffic patterns of the running application and takes preventive flow control actions to avoid congestions. The proposed system entails an application-level prediction table for accurate traffic prediction and a packet injection scheduler for congestion avoidance. The proposed scheme is evaluated by a trace-driven simulator with synthetic traffic traces as well as a real application trace of an instance in the SPLASH-2 benchmark. The results show the superior performance of the proposed scheme with negligible execution overhead.