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Network-on-Chip (NoC) has been made the communication infrastructure for many-core architecture. NoC are subject to congestion, which is claimed to be avoided by many researchers. However, there is no completely understanding of congestion in literature, which hinders its solution. Toward this direction, we firstly carry out study on congestion in this paper. We find that congestion usually occurs at a portion of nodes in a local network region. Moreover, local congestion will significantly decrease system performance and mostly impact some particular communication pairs. Then we attempt to solve local congestion by addressing different local region size, based on Divide-Conquer approach and routing pressure. It avoids congestion in every local region by keeping routing pressure of every local region minimum. Using different local region size will create different routings. Our study shows that the local region size is closely related with the routing performance. When local region size is 5 × 5 the optimal routing performance of large size network could be achieved. [ABSTRACT FROM AUTHOR]

How to precisely measure performance of routing algorithm is an important issue when studying routing algorithm of network-on-chip (NoC). The degree of adaptiveness is the most widely used metric in the literature. However, our study shows that the degree of adaptiveness cannot precisely measure performance of routing algorithm. It cannot account for why routing algorithm with high degree of adaptiveness may have poor performance. Simulation has to be carried out to evaluate performance of routing algorithm. In this paper, we propose a new metric of routing pressure for measuring performance of routing algorithm. It has higher precision of measuring routing algorithm performance than the degree of adaptiveness. Performance of routing algorithm can be evaluated through routing pressure without simulation. It can explain why congestion takes place in network. In addition, where and when congestion takes place can be pointed out without simulation. [ABSTRACT FROM AUTHOR]