Rapid estimation of instruction cache hit rates using loop profiling

Abstract

Estimation of the hit rate curve for an application is the first step in application specific cache tuning. Several techniques have been proposed to meet this objective however most of these have dealt with the data cache with little attention to the instruction cache. In this paper, we propose a novel, lightweight and highly scalable technique for rapid estimation of the instruction cache hit rate curve for a given application. Our technique works at the basic block level and relies on a one-time loop profiling of the weighted control flow graph of the application followed by estimation of the hit rate for different cache sizes. It accounts for the spatial and temporal locality separately and is sensitive to the cache size as well as block size. The proposed technique is highly accurate and when compared with results from an actual cache simulator, the mean error in estimation ranged from 1.11% to 2.46% for the benchmarks tested.