Energy-Aware Page Migration in PCM-DRAM Hybrid Memory

Phase Change Memory is an emerging technology for main memory design. It is denser, non-volatile and consumes lower idle energy compared to traditional DRAM. Yet its limited write endurance and inherent greater write latency and energy constrain its replacement of DRAM. Based on these observations, many studies combine DRAM and PCM in main memory system. However, DRAM's idle energy is the bottleneck of energy reduction for the hybrid memory and no previous work paid attention to it. In this paper, we propose a memory power transition policy and two page migration strategies (inner-DRAM and PCM-DRAM) to reduce the DRAM idle energy as well as the overall energy consumption. We experimentally compare our design with other previous hybrid memory systems under cycle-accurate simulation. Experiments of various benchmark workloads show that our system achieves significantly better improvements over other techniques in terms of metrics Energy and Energy-Delay2.