Dynamic pseudo cache association for energy reduction of L2 caches

Abstract

Mobile systems are typically operated on batteries and, thus, energy consumption is the first class citizen in them. L2 caches help improve performance but increase energy consumption due to their large sizes. An effective solution to this problem is to selectively shut down some L2 cache ways, which, however, reduces L2 cache associativity and performance, and, thus, limits effectiveness in reducing energy consumption. To overcome this limitation, we re-invent the conventional pseudo cache association scheme to logically increase associativity of way-shut downed L2 caches. To reduce energy consumption in tag ways, a partial tag-based pseudo way prediction scheme is developed. Our pseudo cache association scheme is made to be dynamic to remove the need of static profiling for finding an energy-optimal cache configuration. Experimental results show that our proposed dynamic scheme reduces energy consumptions of L2 caches by 20% over the best performing conventional static cache configuration.