Fully Exploiting PCM Write Capacity Within Near Zero Cost Through Segment-Based Page Allocation

Improving the endurance of phase change memory (PCM) is a fundamental issue when PCM technology is considered as an alternative to main memory usage. Existing wear-leveling techniques overcome this challenge through constantly remapping hot virtual pages, thus engendering a fair amount of extra write operations to PCM and imposing considerable performance and energy overhead. Our observation is that it is unnecessary to fully balance the accesses to different physical page frames during the execution of each process. Instead, since endurance is a lifetime factor, the hot virtual pages of different processes can be mapped to different physical pages in the PCM. Leveraging this property, we develop a wear-resistant page allocation algorithm, which exploits the diverse write characteristics of different program segments to improve PCM write endurance within almost no extra remapping cost in terms of energy and performance. The results of experiments conducted based on SPEC benchmarks show that the proposed technique can prolong PCM lifetime by hundreds of times within nearly zero searching and remapping overhead.