NeTS: Small: Low Latency Scheduling for Data Centers

数据中心是任何现代计算基础设施的主干。因此，数据中心在高资源利用率和低延迟的情况下运行，对于构建高性能的计算系统至关重要。该项目的主要目标是开发这样一个数据中心。从历史上看，数据中心架构的灵感来自互联网中的拥塞控制，即在终端以分布式方式做出决策。这为数据中心带来了强大、可扩展的架构，但存在高延迟和低资源利用率的问题。与互联网的拥塞控制相比，在交换机上进行调度？现代高带宽互联网路由器的核心？根本上要靠集中管控的能力。在过去的二十年里，在交换机调度方面取得了很大的进展，产生了具有高资源利用率和极低延迟的算法。因此，通过应用交换机调度的设计原则，有可能实现资源利用率高、延迟低的数据中心架构。总之，通过从互联网路由器而不是互联网拥塞控制派生设计原则，为数据中心开发极低延迟、高性能的调度体系结构具有巨大的机会。这正是这个项目的着力点。实现这一目标面临两大挑战。首先，开发一个可实现的、高性能的交换机调度解决方案。PI最近提出的现有理论上的最优解过于复杂，难以实现。因此，需要开发这样一个解决方案的简单实现。这个项目将通过利用统计物理中的自旋玻璃理论的随机化(马尔可夫链蒙特卡罗)和平均场近似来实现这一目标。其次，将交换机的调度算法转换为数据中心的调度算法是具有挑战性的。该项目应开发一个仿真框架，允许以无缝方式进行这种转换。这将通过利用流级调度和受可逆排队网络启发的分组级调度之间的联系来实现。智能优点：该项目将推进通信网络可实现的调度算法的设计和分析。在智力上，这将促进随机逼近算法的理论、统计物理的逼近技术和排队网络的仿真方法。此项目的成功结果将表明，使用经典电话网络和ATM网络设计背后的原则来构建数据中心比使用Internet拥塞控制的设计原则更好。更广泛的影响：该项目的成功结果将为开发低延迟和高效的数据中心铺平道路。反过来，这将允许开发以前不可行的计算基础设施。鉴于跨学科的高性能计算基础设施的核心重要性，该项目的成功结果将产生广泛的影响。这项工作将对目前蓬勃发展的网络行业产生兴趣，在该行业，初创企业和大型组织都在努力开发基于软件定义的网络理念的下一代数据中心。从某种意义上说，这项工作将为他们提供一条实现最终目标的途径。拟议的研究将通过在期刊、会议和研讨会上发表的出版物向社会传播。这项研究成果也可能被整合到PI在麻省理工学院定期教授的研究生网络课程中。

A data center is the backbone of any modern computational infrastructure. Therefore, it is of utmost importance to operate data center at high resource utilization and low latency to build a high-performance computation system. The primary goal of this project is to develop such a data center.Historically, the data center architecture has been inspired by congestion control in the Internet, where decisions are made at the end-points in a distributed manner. This has led to robust, scalable architecture for data center, but suffers from high latency and low resource utilization. In contrast to the Internet congestion control, scheduling in a switch ? core of modern high-bandwidth Internet router ? fundamentally relies on the ability to exercise centralized control. Over the past two decades, much progress has been made in the context of switch scheduling resulting into algorithm with high resource utilization and extremely low latency. Therefore, by applying design principles from switch scheduling, there is a potential to achieve data center architecture that has high resource utilization and low latency. In summary, there is a massive opportunity for developing extremely low-latency, high-performance scheduling architecture for data center by deriving design principles from Internet routers rather than Internet congestion control. This is precisely the focal point of this project. There are two major challenges in achieving this goal. First, developing an implementable and high-performance solution for switch scheduling. The existing theoretically optimal solutions, recently developed by PI, are too complex to implement. Therefore, developing a simple implementation of such a solution is required. This project will achieve this goal by utilizing randomization (a la Markov Chain Monte Carlo) and mean-field approximations from spin glass theory in Statistical Physics. Second, transforming a scheduling algorithm for a switch to a scheduling algorithm for data center is challenging. This project shall develop an emulation framework that will allow for such a transformation in a seamless manner. This will be achieved by utilizing connections between flow-level scheduling with packet-level scheduling inspired by reversible queuing networks.Intellectual Merit: This project will advance the design and analysis of implementable scheduling algorithms for communication networks. Intellectually, this will advance theory of randomized approximation algorithm, approximation techniques from statistical physics and emulation approaches from queuing network. The successful outcome of this project will suggest that it is better to architect a data center using principles behind the design of classical telephone network and ATM network rather than that of Internet congestion control. Broader Impacts: The successful outcome of this project will pave way for the development of low latency and efficient data centers. This, in turn, will allow for developing computational infrastructures that were not feasible before. Given the central importance of high-performance computational infrastructure across disciplines, successful outcome of this project will have a broad impact. This work will be of interest to currently vibrant networking industry where start-ups and big organizations alike are trying to develop the next generation data center riding on the software defined networking philosophy. In a sense, this work will provide a path to achieve their end goal. The proposed research will be disseminated to the community via publications in journals, conferences and workshops. The research outcome is also likely to be integrated in the graduate networking course that PI regularly teaches at MIT.