Power-aware buddy system and task group scheduler

Memory is responsible for a large and increasing fraction of the energy consumed by computers. To address this challenge, memory manufacturers have developed memory devices with different power states. In order to more effectively manage the power states in the operating system, in this paper, we propose a rank-sensitive buddy system (RS-Buddy) which clusters pages together to prolong the idle time of memory ranks without breaking defragmentation characteristics. For the purpose of decreasing unnecessary frequent mode transitions, we introduce a power-aware task group scheduler (PATGS) that groups the threads which access the same rank together to schedule while sustaining system fairness. Finally, we integrate state-of-the-art mode control policies with our RS-Buddy and PATGS, with experimental results demonstrating that our algorithms can improve the power efficiency from 25.31% to 27.35% compared with state-of-the-art studies.