HW-PCM:A Novel Heat-aware PCM Caching Mechanism

Phase Change Memory(PCM),one of the most promising alternatives for DRAMs,attracts intensive attentions from both academic and industry communities,as it provides appealing characteristics such as the non-volatility,low static power,good scalability,high storage density,and good read latency.However,PCM suffers from long write latencies and therefore one of the methods is to use it as the read cache.Even though PCM functions as the read cache,lengthy write latencies of PCM still affect the overall cache read throughput.In order to solve this problem under the limited write throughput,we propose a novel Heat-aWare PCM caching mechanism(HW-PCM),which improves the cache read throughput utilizations by minimizing data page in and out times and maximizing read/write ratios of the PCM cache.Specifically,HW-PCM optimizes existing LRU algorithms to effectively filter hot data(high access frequencies)and caches them in the PCM cache,and less frequently accessed data is assigned to other places.We implement and evaluate our design under real-world workload traces.Experiment results show that the proposed Heat-aWare PCM caching mechanism improves the read throughput by up to 32.6%.