CSR:Medium: A Cross-stack Approach to Reduce Memory Carbon in Cloud Data Centers

内存容量的缩放（即每个内存芯片的比特数）越来越落后于其他系统组件的密度缩放（例如，CPU芯片中每个区域的内核数）。因此，今天一个典型的云服务器包含100个内存芯片，在目前的扩展趋势下，可能会增加到1000个；在每台服务器上制造和驱动这么多内存芯片对环境来说是不可持续的。该项目将探索如何共同设计硬件和软件，以在内存中更密集地存储值，并减少制造内存的数量和功耗，以减少未来云数据中心的碳足迹。虽然先前的技术已经探索了硬件中的内存压缩，但他们只探索了如何在最基本的软件场景中做到这一点-本机运行单个程序，除了内存之外几乎没有访问任何内容。云中的软件栈要复杂得多；用户应用程序在虚拟机中运行，与并置的工作负载并发运行，并且经常大量使用操作系统（OS）文件缓存和其他内存缓存。这个名为CloudComp的项目将与云系统软件的不同层（例如，管理程序、存储堆栈、内存数据库、作业调度器）共同设计硬件内存压缩，以实现能够满足云中的各种需求和应用场景的实际部署。CloudComp将汇集计算机体系结构、云计算、操作系统、存储系统和数据库方面的研究人员。为了促进现实世界的影响，该项目将构建和发布硬件内存压缩的真实系统原型，并与工业界密切合作。通过为未来的云数据中心提供一种扩展内存大小的替代途径，CloudComp将有助于减少云计算对气候变化的影响，而不是制造更多内存芯片的强力方法。将更多的数据密集地存储到可用的内存中也可以在其他方面对气候有利，例如实现更大规模和/或更精细的气候建模和模拟。CloudComp包括教育和参与活动，以扩大参与研究和吸引新学生，特别是从代表性不足的群体中寻找学生。CloudComp将积极让本科生参与构建真实系统原型，培养他们对研究的好奇心。最后，通过CloudComp获得的跨层见解将有助于指导其他互补内存系统技术的研究，以对抗内存的缓慢物理扩展。CloudComp的部分资金由国家气候发现云（NDC-C）计划提供，该项目的核心目的是通过这项研究减少云系统的碳排放。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The scaling of memory capacity (i.e., bits per memory chip) increasingly lags behind the density scaling of other system components (e.g., cores per area in a CPU chip). As a result, a typical cloud server today contains 100s of memory chips, which may increase to 1000s under the current scaling trend; manufacturing and powering so many memory chips per server will be environmentally unsustainable. This project will explore how to co-design hardware and software to store values more densely in memory and reduce how much memory to manufacture and power to reduce the carbon footprint of future cloud data centers. While prior art has explored memory compression in hardware, they have only explored how to do so in the most rudimentary software scenarios - natively running a single program that accesses little to nothing beyond memory. The software stack in cloud is much more complex; user applications run in virtual machines, concurrently with collocated workloads, and often heavily exercise the operating system (OS) file cache and other in-memory caches. This project - CloudComp- will co-design hardware memory compression with different layers of the cloud system software (e.g., hypervisor, storage stack, in-memory databases, job scheduler) to enable practical deployment that can satisfy the diverse requirements and application scenarios in cloud. CloudComp will bring together researchers in computer architecture, cloud computing, OS, storage systems, and databases. To facilitate real world impact, this project will build and release real-system prototypes of hardware memory compression and partner closely with industry. By enabling an alternative path to scale up the effective size of the memory size for future cloud data centers, CloudComp will help reduce the impact of cloud computing on climate change over the brute-force approach of making more memory chips. Densely storing more data into the available amount of memory can also benefit climate in other ways such as enabling bigger-scale and/or finer-resolution climate modeling and simulation. CloudComp includes educational and engagement activities to broaden participation in research and attract new students, especially seeking out students from underrepresented groups. CloudComp will actively involve undergraduate students in building real-system prototypes to cultivate their curiosity for research. Lastly, the cross-layer insights gained through CloudComp will help guide the research of other complementary memory system techniques to combat the slowing physical scaling of memory. CloudComp is funded in part by the National Discovery Cloud for Climate (NDC-C) program as a core purpose of the project is to reduce the carbon emissions of cloud systems through this research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.