CACHE MANAGEMENT ON MULTI-CORE SYSTEMS

Abstract

The impact of various cache replacement policies act as the main deciding factor of system performance and efficiency in Chip Multi-core Processors. It is imperative for any level of cache memory in a multi-core architecture to have a well-defined, dynamic replacement algorithm in place to ensure consistent superlative performance. Many existing cache replacement policies such as Least Recently Used (LRU) policy have proved to work well in the shared Level 2 (L2) cache for most of the data set patterns generated by single threaded applications. When it comes to parallel multi- threaded applications that generate differing patterns of workload at different intervals, the conventional replacement policies can prove sub-optimal, as they generally do not abide by the spatial and temporal locality theories and do not acquaint dynamically to the changes in the workload. This thesis therefore proposes Logical Cache Partitioning technique which logically partitions the cache elements into four zones based on their “likeliness‟ to be referenced by the processor in the near future. Replacement candidates are chosen from the zones in the ascending order of their likeliness factor to minimize the number of cache misses and increase cache hits. The proposed technique was implemented on a four core system and is effective at improving cache performance and offer an improvement of up to 9% in overall hits at the L2 cache level and an IPC (Instructions Per Cycle) speedup of up to 1.048 times that of Least Recently Used (LRU) technique for a wide range of multithreaded benchmarks.