SRS-Mig: Selection and Run-time Scheduling of page Migration for improved response time in hybrid PCM-DRAM memories

Hybrid memory systems with a combination of DRAM and Non-Volatile Memory (NVM) types can make use of scalability and performance of both NVM and DRAM. Random placement of pages in Phase Change Memory (PCM) with more write accesses incurs higher write latencies. So, migrating write intensive pages from PCM to DRAM helps to reduce execution time and memory response time for applications. Existing techniques mainly focus on selecting the page migration candidate and migrate it immediately when it becomes eligible. This direct migration approach can hamper the response time of regular memory accesses. So, in our paper, we identify migration candidates and in addition, schedule when they can be migrated to DRAM. To realize this, we have used Selection and Run-time Scheduling of page Migration (SRS-Mig), a frame-based scheduling approach for migrations and read/write requests. SRS-Mig reduces migration overhead and guarantees future accesses to migrated pages to yield an improved execution time and memory response time for the applications. Experimental evaluation shows 30% improvement in execution time; 26% improvement memory response time, and considerable energy savings with the existing baseline techniques.