A tag-based cache replacement

Abstract

Conventional cache replacement policies use access information of each cache block for replacement decisions. We observe that there are many identical tags across different cache sets because programs exhibit spatial locality. The number of different tags in cache memory is significantly less than the total number of cache blocks in a cache. We propose a tag-based replacement that uses access frequency and recency of tags instead of cache blocks for the replacement decision. The tag-based replacement reduces the average miss rate of the baseline 1MB L2 cache by 15% over conventional LRU with 95% status bits reduction over conventional LRU. The performance improvement of a processor using the tag-based replacement is up to 40% with an average of 4.5% over LRU.