Mini-Rank: A Power-EfficientDDRx DRAM Memory Architecture

Memory power consumption has become a severe concern in multi-core computer platforms. As memory data rate, capacity and bandwidth are being pushed higher and higher, the power consumption of memory systems becomes a significant part in the overall system power profile. Conventional memory systems do not provide an efficient mechanism for managing its power and performance tradeoff. We propose a novel mini-rank architecture for DDRx memories to reduce memory power consumption by breaking each DRAM rank into multiple narrow mini-ranks and activating fewer devices for each request. We also propose a heterogeneous mini-rank design to further improve the performance-power tradeoff for each workload based on its memory access behavior and bandwidth requirement. The evaluation results show that homogeneous mini-rank significantly reduces memory power with small performance loss. For instance, using four-core multiprogramming workloads, a x32 mini-rank configuration reduces memory power by 19.5 percent with 1.3 percent performance loss on average for memory-intensive workloads. Heterogeneous mini-rank further improves the balance between the performance and power saving. For instance, it reduces the memory power by up to 38.0 percent with an average performance loss of 2.4 percent, compared with a conventional memory system. In comparison, the x32 homogeneous mini-rank reduces memory power by up to 25.4 percent; while the x8 homogeneous mini-rank incurs performance loss by up to 19.3 percent. Furthermore, heterogeneous mini-rank achieves consistently good performance-power tradeoff for workloads made by programs of diverse memory access behavior and bandwidth requirement.