MemScale: Active Low-Power Modes for Main Memory

Main memory is responsible for a large and increasing fraction of the energy consumed by servers. Prior work has focused on exploiting DRAM low-power states to conserve energy. However, these states require entire DRAM ranks to be idled, which is difficult to achieve even in lightly loaded servers. In this paper, the authors propose to conserve memory energy while improving its energy proportionality by creating active low-power modes for it. Specifically, the authors propose MemScale, a scheme wherein the authors apply Dynamic Voltage and Frequency Scaling (DVFS) to the memory controller and Dynamic Frequency Scaling (DFS) to the memory channels and DRAM devices.