Dynamic associativity management using utility based way-sharing

Abstract

The non-uniform distribution of memory accesses of todays applications affect the performance of cache memories. Due to such non-uniform accesses some sets of large sized caches are used heavily while some other sets are used lightly. This paper presents a technique WS-DAM, to dynamically increase the associativity of the heavily used sets without increasing the cache size. The heavily used sets can use the idle ways of the lightly used sets to distribute the load. A limited number of ways from every lightly used set are reserved for the heavily used sets. To search a block in a heavily used set, both: the set and the entire reserve area is searched. To reduce the cost of searching the entire reserve storage an additional tag-array is used. During execution the sets are re-categorized at intervals. The proposed technique needs much lesser storage, area and power overhead as compared to the other similar techniques. It improves both miss rate and CPI by 14.46% and 6.63% respectively as compared to an existing technique called V-Way. WS-DAM is also compared with another existing proposal called CMP-VR and it improves the performance by 9% and 4.20% in terms of miss-rate and CPI respectively.