ReD: A reuse detector for content selection in exclusive shared last-level caches

Abstract

The reference stream reaching a chip multiprocessor Shared Last-Level Cache (SLLC) shows poor temporal locality, making conventional cache management policies inefficient. Few proposals address this problem for exclusive caches. In this paper, we propose the Reuse Detector (ReD), a new content selection mechanism for exclusive hierarchies that leverages reuse locality at the SLLC, a property that states that blocks referenced more than once are more likely to be accessed in the near future. Being placed between each L2 private cache and the SLLC, ReD prevents the insertion of blocks without reuse into the SLLC. It is designed to overcome problems affecting similar recent mechanisms (low accuracy, reduced visibility window and detector thrashing). ReD improves performance over other state-of-the-art proposals (CHAR, Reuse Cache and EAF cache). Compared with the baseline system with no content selection, it reduces the SLLC miss rate (MPI) by 10.1% and increases harmonic IPC by 9.5%.