Bloom filter-based dynamic wear leveling for phase-change RAM

Phase Change RAM (PCM) is a promising candidate of emerging memory technology to complement or replace existing DRAM and NAND Flash memory. A key drawback of PCMs is limited write endurance. To address this problem, several static wear-leveling methods that change logical to physical address mapping periodically have been proposed. Although these methods have low space overhead, they suffer from unnecessary data migrations thereby failing to exploit the full lifetime potential of PCMs. This paper proposes a new dynamic wear-leveling method that reduces unnecessary data migrations by adopting a hot/cold swapping-based dynamic method. Compared with the conventional hot/cold swapping-based dynamic method, the proposed method requires only a small amount of space overhead by applying Bloom filters to the identification of hot and cold data. We simulate our method using SPEC2000 benchmark traces and compare with previous methods. Simulation results show that the proposed method reduces unnecessary data migrations by 58~92% and extends the memory lifetime by 2.18~2.30 times over previous methods with a negligible area overhead of 0.3%.