Power-efficiency has become one of the most critical concerns for HPC as we continue to scale computational capabilities. A significant fraction of system power is spent on large main memories, mainly caused by the substantial amount of DIMM standby power needed. However, while necessary for some workloads, for many workloads large memory configurations are too rich, i.e., these workloads only make use of a fraction of the available memory, causing unnecessary power usage. This observation opens new opportunities for power reduction by powering DIMMs on and off depending on the current workload. In this article, we propose footprint-based DIMM hotplug that enables a compute node to adjust the number of DIMMs that are powered on depending on the memory footprint of a running job. Our technique relies on two main subcomponents—memory footprint monitoring and DIMM management—which we both implement as part of an optimized page management system with small control overhead. Using Linux's memory hotplug capabilities, we implement our approach on a real system, and our results show that our proposed technique can save 50.6–52.1 percent of the DIMM standby energy and the CPU+DRAM energy of up to 1.50 Wh for various small-memory-footprint applications without loss of performance.

中文翻译：

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基于封装的 DIMM 热插拔

随着我们不断扩展计算能力，能效已成为 HPC 最关键的问题之一。很大一部分系统功率消耗在大型主存储器上，这主要是由于需要大量的 DIMM 待机功率。然而，虽然对于某些工作负载是必要的，但对于许多工作负载而言，大内存配置过于丰富，即这些工作负载仅使用可用内存的一小部分，从而导致不必要的功耗。这一观察通过根据当前工作负载打开和关闭 DIMM 为降低功耗开辟了新的机会。在本文中，我们提出了基于内存占用的 DIMM 热插拔，它使计算节点能够根据正在运行的作业的内存占用来调整开启的 DIMM 数量。我们的技术依赖于两个主要的子组件——内存占用监控和 DIMM 管理——我们都将它们作为优化页面管理系统的一部分来实现，控制开销很小。使用 Linux 的内存热插拔功能，我们在真实系统上实现了我们的方法，结果表明，我们提出的技术可以为各种小内存节省 50.6-52.1% 的 DIMM 待机能量和高达 1.50 Wh 的 CPU+DRAM 能量- 占用应用程序而不会损失性能。