Split ways: An efficient replacement policy for larger sized cache memory

Abstract

As the data requirement of today’s application is increasing the size of the cache memory in a multicore processor is also increasing. A multicore processor has many levels of cache memory. The Last Level Cache (LLC) is normally shared by all the cores and its size must be large enough to handle today’s data intensive applications. Such larger sized set-associative LLC facing major challenges to efficiently implement the replacement policy of its sets. As the number of ways are increasing in the LLC, the replacement policy becomes a bottleneck of the system. To improve the performance of the system and to reduce the hardware overhead, in this paper we propose a simple but hardware efficient replacement policy for the larger sized LLCs. We call the techniques as SplitWays as it divides (splits) the ways of a set into multiple groups called wayGroups. Each wayGroup maintains its own replacement policy. Experimental analysis using full-system simulator found that the proposed technique reduces the hardware overhead by up to 66% without any performance degradation.