A hybrid cache replacement policy for heterogeneous multi-cores

Abstract

Future generation computer architectures are en deavoring to achieve high performance without compromise on energy efficiency. In a multiprocessor system, cache miss degrades the performance as the miss penalty scales by an exponential factor across a shared memory system when com pared to general purpose processors. This instigates the need for an efficient cache replacement scheme to cater to the data needs of underlying functional units in case of a cache miss.Minimal cache miss improves resource utilization and reduces data movement across the core which in turn contributes to a high performance and lesser power dissipation. Existing replacement policies has several issues when implemented in a heterogeneous multi-core system. The commonly used LRU replacement policy does not offer optimal performance for applications with high dependencies. Motivated by the limitations of the existing algorithms, we propose a hybrid cache replacement policy which combines Least Recently Used (LRU) and Least Frequently Used (LFU) replacement policies.Each cache block has two weighing values corresponding to LRU and LFU policies and a cumulative weight is calculated using these two values. Conducting simulations over wide range of cache sizes and associativity, we show that our proposed approach has shown increased cache hit to miss ratio when compared with LRU and other conventional cache replacement policies.

A Computationally Efficient P-LRU based Optimal Cache Heap Object Replacement Policy

“…The drawbacks of existing cache replacement algorithms motivated the authors in [16] to put forward a policy called Recency Frequency Replacement (RFR) that combines recency of a cache block with frequency i.e., a hybrid of LRU and LFU. Two weighing values are associated to every cache block that corresponds to LRU and LFU thereby maintaining a balance between them and then cumulative weight is also computed from the two values.…”