Matching cache access behavior and bit error pattern for high performance low Vcc L1 cache

Young-Geun Choi, Sungjoo Yoo, Sunggu Lee, Jung Ho Ahn

Abstract: Cache is a roadblock towards low supply voltage (Vcc). It is mainly because low Vcc incurs process variation-induced bit errors in large SRAM in cache. Existing approaches for low Vcc cache suffer from low performance due to reduced effective capacity, long latency to correct errors, and increased misses due to accesses to faulty words. In our work, we propose a word-level sub-block disable-based method which increases the utilization of available cache capacity. Our key idea is to minimize accesses to faulty words. To do that, we propose utilizing access behavior history in allocating cache resource with faulty words. In addition, we propose remapping cache words inside of cache line in order to better match both access and error patterns. Experimental results show that the proposed method gives average 21.8% (up to 34.0%) performance improvement with a small area overhead in L1 and L2 caches.