DAAIP: Deadblock Aware Adaptive Insertion Policy for High Performance Caching

Abstract

The commonly used LRU replacement policy for management of shared last-level cache (LLC) is not efficient as the policy is sharing-oblivious. LRU policy is suitable for applications which show a high-degree of data locality i.e. applications which are cache-friendly. However, applications with working data set greater than the available cache size or poor temporal locality perform poorly with LRU as most of the cache lines inserted by them simply traverse from MRU to LRU position without being re-referenced. Such applications are streaming in their cache behaviour and have very less data reuse. LRU policy makes inefficient use of shared caches for application mixes which are a combination of cache-friendly and streaming applications as the policy treats each cache line independently and doesn't learn from application's past cache reuse behaviour. We show that simple adaptive changes to the insertion policy can significantly improve system's performance. We propose Deadblock Aware Adaptive Insertion Policy (DAAIP) which dynamically adapts to the changing cache behaviour of applications sharing the LLC. DAAIP protects the data of application having high temporal locality from high access rate thrashing/streaming applications. Our proposed mechanism monitors each application at-runtime using cost-effective hardware circuits. The information collected is used to dynamically modify the insertion policy and implicitly partition the cache in favour of application showing more data locality. Our evaluation, with 39 multiprogrammed workloads, shows that DAAIP improves performance of dual-core system by up to 21% and on an average 5.8% over LLC caches managed by SRRIP replacement policy. We show that DAAIP also outperforms state-of-the-art cache replacement policy ABRip by 4.6% on system throughput metric.