Adaptive Page Packing and Storing Method for PCM-Flash Hybrid Memory Structure

This paper presents an advanced PCM-Flash hybrid memory structure for the integrated memory-disk (IMD) structure merging the conventional main memory and disk storage into a single memory layer. The proposed structure can enhance overall write access latency of PCM (phase change memory)-Flash hybrid array and the amount of sequentially allocated data onto physical Flash memory area by applying PCM preference write policy and also designing additional page packing module. Thus, these two modules can maximize the use of PCM memory space to achieve both fast access latency and high Flash endurance by aggressively bounding adjacent pages. Thus, our advanced PCM-Flash hybrid memory structure can provide optimal performance by considering intrinsic characteristics of PCM and Flash memory devices and overcome PCM and Flash asymmetric access latency gap via PCM preference write policy. Our experimental results show that energy consumption of our advanced PCM-Flash hybrid memory structure can be improved by around 39%, and access latency can be reduced by 45%, compared to the basic model.