Novel Metric for Load Balance and Congestion Reducing in Network on-Chip

The Network-on-Chip (NoC) is an alternative pattern that is considered as an emerging technology for distributed embedded systems. The traditional use of multi-cores in computing increase the calculation performance; but affect the network communication causing congestion on nodes which therefore decrease the global performance of the NoC. To alleviate this problematic phenomenon, several strategies were implemented, to reduce or prevent the occurrence of congestion, such as network status metrics, new routing algorithm, packets injection control, and switching strategies. In this paper, we carried out a study on congestion in a 2D mesh network, through various detailed simulations. Our focus was on the most used congestion metrics in NoC. According to our experiments and performed simulations under different traffic scenarios, we found that these metrics are less representative, less significant and yet they do not give a true overview of reading within the NoC nodes at a given cycle. Our study shows that the use of other complementary information regarding the state of nodes and network traffic flow in the design of a novel metric, can really improve the results. In this paper, we put forward a novel metric that takes into account the overall operating state of a router in the design of adaptive XY routing algorithm, aiming to improve routing decisions and network performance. We compare the throughput, latency, resource utilization, and congestion occurrence of proposed metric to three published metrics on two specific traffic patterns in a varied packets injection rate. Our results indicate that our novel metric-based adaptive XY routing has overcome congestion and significantly improve resource utilization through load balancing; achieving an average improvement rate up to 40 % compared to adaptive XY routing based on the previous congestion metrics.