Introducing OVP awareness to achieve an efficient permanent defect locating

Fault-tolerance now plays an important role in covering the increasing soft/hard error rates in electronic devices that accompany the advances in process technologies. Research shows that wear-out faults have a gradual onset, starting with a timing fault and then eventually leading to a permanent fault. Error detection is thus a required function to maintain execution correctness. Currently, however, many highly dependable methods to cover permanent faults are commonly over-designed for very frequent checking, due to the lack of the awareness of the potential fault rate in the near future. In this research, we propose a method to lower the cost of locating the permanent defects by introducing an operation vulnerable probability (OVP). Specifically, this method segments a long data-path by means of check instructions which tag the segment with their check results and thus allow the later permanent error locating to be carried out inside the segmented zone. We find that our approach saves 64% energy per 10M executions by setting the OVP threshold at 20%.