Congestion-Controlled Best-Effort Communication for Networks-on-Chip

Congestion has negative effects on network performance. In this paper, a novel congestion control strategy is presented for networks-on-chip (NoC). For this purpose we introduce a new communication service, congestion-controlled best-effort (CCBE). The load offered to a CCBE connection is controlled based on congestion measurements in the NoC. Link utilization is monitored as a congestion measure, and transported to a model predictive controller (MPC). Guaranteed bandwidth and latency connections in the NoC are used for this, to assure progress of link utilization data in a congested NoC. We also present a simple but effective model for link utilization for the model-based predictions. Experimental results show that the presented strategy is effective and has reaction speeds of several microseconds which is considered acceptable for realtime embedded systems