Modified LRU policies for improving second-level cache behavior

Main memory accesses continue to be a significant bottleneck for applications whose working sets do not fit in second-level caches. With the trend of greater associativity in second-level caches, implementing effective replacement algorithms might become more important than reducing conflict misses. After showing that an opportunity exists to close part of the gap between the OPT and the LRU algorithms, we present a replacement algorithm based on the detection of temporal locality in lines residing in the L2 cache. Rather than always replacing the LRU line, the victim is chosen by considering both its priority in the LRU stack and whether it exhibits temporal locality or not. We consider two strategies which use this replacement algorithm: a profile-based scheme where temporal locality is detected by processing a trace from a training set of the application and an on-line scheme, where temporal locality is detected with the assistance of a small locality table. Both schemes improve on the second-level cache miss rate over a pure LRU algorithm, by as much as 12% in the profiling case and 20% in the dynamic case