APP-LRU: A new page replacement method for PCM/DRAM-based hybrid memory systems

Phase change memory (PCM) has become one of the most promising storage media particularly for memory systems, due to its byte addressability, high access speed, and low energy consumption. In addition, hybrid memory systems involving both PCM and DRAM can utilize the merits of both media and overcome some typical drawbacks of PCM such as high write latency and limited lifecycle. In this paper, we present a novel page replacement algorithm called APP-LRU (Access-Pattern-prediction-based LRU) for PCM/DRAM-based hybrid memory systems. APP-LRU aims to reduce writes to PCM while maintaining stable time performance. Particularly, we detect read/write intensity for each page in the memory, and put read-intensive pages into PCM while placing write-intensive pages in DRAM. We conduct trace-driven experiments on six synthetic traces and one real OLTP trace. The results show that our proposal is able to reduce up to 5 times of migrations more than its competitors.