Selective wordline voltage boosting for caches to manage yield under process variations

Abstract

One of the most important hurdles of technology scaling is process variations, i.e., variations in device characteristics. Process variations cause large fluctuations in performance and power consumption in the manufactured chips. In addition, these fluctuations cause reductions in the chip yields. In this work, we present an analysis of a representative high-performance processor architecture and show that the caches have the highest probability of causing yield losses under process variations. We then propose a novel selective wordline voltage boosting mechanism that aims at reducing the latency of the cache lines that are affected by process variations. We show that our approach can eliminate over 80% of the yield losses under medium level of variations, while incurring less than 1% per-access energy overhead on average and less than 4.5% area overhead.