Understanding and Optimizing Power Consumption in Memory Networks

As the amount of digital data the world generates explodes, data centers and HPC systems that process this big data will require high bandwidth and high capacity main memory. Unfortunately, conventional memory technologies either provide high memory capacity (e.g., DDRx memory) or high bandwidth (GDDRx memory), but not both. Memory networks, which provide both high bandwidth and high capacity memory by connecting memory modules together via a network of pointto-point links, are promising future memory candidates for data centers and HPCs. In this paper, we perform the first exploration to understand the power characteristics of memory networks. We find idle I/O links to be the biggest power contributor in memory networks. Subsequently, we study idle I/O power in more detail. We evaluate well-known circuitlevel I/O power control mechanisms such as rapid on off, variable link width, and DVFS. We also adapt prior works on memory power management to memory networks. The adapted schemes together reduce I/O power by 32% and 21%, on average, for big and small networks, respectively. We also explore novel power management schemes specifically targeting memory networks, which yield another 29% and 17% average I/O power reduction for big and small networks, respectively.