Buffering of frequent accesses for reduced cache aging

Abstract

Previous works have shown that typical power management knobs such as voltage scaling or power gating can also be exploited to reduce aging phenomena caused by Negative Bias Temperature Instability (NBTI). We propose a scheme for power-managed caches that allows to significantly improving the aging of the cache thanks to the use of a small buffer that stores a copy of the lines that are most critical for aging, that is, the ones with the least opportunity of being power-managed; by using the buffer instead of the cache when accessing these critical lines, the original cache is preserved and its lifetime is significantly prolonged. As a side effect, this scheme improves total power since the less energy-hungry buffer is accessed most of the time. Experimental analysis shows this scheme allows to achieve significant (>3x on average) lifetime extensions for the cache, with a concurrent energy saving between 18 and 24%, depending on cache size.