Application-Specific Wear Leveling for Extending Lifetime of Phase Change Memory in Embedded Systems

Abstract

Phase change memory (PCM) has been proposed to replace NOR flash and DRAM in embedded systems because of its attractive features. However, the endurance of PCM greatly limits its adoption in embedded systems. As most embedded systems are application-oriented, we can tackle the endurance problem of PCM by exploring application-specific features such as fixed access patterns and update frequencies. In this paper, we propose an application-specific wear leveling technique, called Curling-PCM, to evenly distribute write activities across the whole PCM chip to improve the endurance of PCM in embedded systems. The basic idea is to exploit application-specific features in embedded systems and periodically move the hot region across the whole PCM chip. To reduce the overhead of moving the hot region and improve the performance of PCM-based embedded systems, a fine-grained partial wear leveling policy is proposed for Curling-PCM, by which only part of the hot region is moved during each request handling period. Experimental results show that Curling-PCM can effectively evenly distribute write traffic for a prime application of PCM in embedded systems. We expect this paper can serve as a first step toward the full exploration of application-specific features in PCM-based embedded systems.