NoCAlert: An On-Line and Real-Time Fault Detection Mechanism for Network-on-Chip Architectures

The widespread proliferation of the Chip Multi-Processor (CMP) paradigm has cemented the criticality of the on-chip interconnection fabric. The Network-on-Chip (NoC) is becoming increasingly susceptible to emerging reliability threats. As technology feature sizes diminish into the nanoscale regime, reliability and process variability artifacts within the NoC start to become prominent. The need to detect the occurrence of faults at run-time is steadily becoming imperative. In this work, we propose NoCAlert, a comprehensive on-line and real-time fault detection mechanism that demonstrates 0% false negatives within the interconnect, for the fault model and stimulus set used in this study. Based on the concept of invariance checking, NoCAlert employs a group of lightweight micro-checker modules that collectively implement real-time hardware assertions. The checkers operate seamlessly and concurrently with normal NoC operation, thus eliminating the need for periodic, or triggered-based, self-testing. More importantly, 97% of the faults are detected instantaneously. Extensive cycle-accurate simulations in a 64-node CMP demonstrate the efficacy of the proposed technique. Finally, hardware synthesis results using commercial 65 nm technology libraries indicate minimal area and power overhead of 3% and less than 1%, respectively, and negligible impact on the router's critical path.