Preprocessing of Scenarios for Fast and Efficient Routing Reconfiguration in Fault-Tolerant NoCs

Newest processes of CMOS manufacturing allow integrating billions of transistors in a single chip. This huge integration enables to perform complex circuits, which require an energy efficient communication architecture with high scalability and parallelism degree, such as a Network-on-Chip (NoC). However, these technologies are very close to physical limitations implying the susceptibility increase of faults on manufacture and at runtime. Therefore, it is essential to provide a method for efficient fault recovery, enabling the NoC operation even in the presence of faults on routers or links, and still ensure deadlock-free routing even for irregular topologies. A preprocessing approach of the most probable fault scenarios enables to anticipate the computation of deadlock-free routings, reducing the time necessary to interrupt the system operation in a fault event. This work describes a preprocessing technique of fault scenarios based on forecasting fault tendency, which employs a fault threshold circuit and a high-level software that identifies the most relevant fault scenarios. We propose methods for dissimilarity analysis of scenarios based on measurements of cross-correlation of link fault matrices. At runtime, the preprocessing technique employs analytic metrics of average distance routing and links load for fast search of sound fault scenarios. Finally, we use RTL simulation with synthetic traffic to prove the quality of our approach.