WearMon: Reliability monitoring using adaptive critical path testing

As processor reliability becomes a first order design constraint, this research argues for a need to provide continuous reliability monitoring. We present WearMon, an adaptive critical path monitoring architecture which provides accurate and real-time measure of the processor's timing margin degradation. Special test patterns check a set of critical paths in the circuit-under-test. By activating the actual devices and signal paths used in normal operation of the chip, each test will capture up-to-date timing margin of these paths. The monitoring architecture dynamically adapts testing interval and complexity based on analysis of prior test results, which increases efficiency and accuracy of monitoring. Experimental results based on FPGA implementation show that the proposed monitoring unit can be easily integrated into existing designs. Monitoring overhead can be reduced to zero by scheduling tests only when a unit is idle.