Feedback Techniques for Integrating Power Management and Quality of Service in Servers

对功耗问题的日益关注以及最近在计算机系统中提高能效和散热的方法并没有立即转化为丰富的、适应性强的、功耗感知的应用程序。这种缺乏有效性的情况在功耗感知的实时计算中尤为明显，在努力弥合硬件和软件之间的差距的情况下，通常局限于开发通过调制相对高的-电平硬件控制，如电压缩放和频率缩放。 这种方法的问题是，硬件控制操作在太大的水平是有效的动态，穷人modeled.This项目开发了一个基于反馈的，控制理论的方法来优化和平衡，在运行时，功耗和实时性能的应用场景。 这种方法不仅将硬件级电源管理技术与实时和服务质量（QoS）约束相结合，而且将不同粒度的硬件电源管理技术集成到一个统一的框架中，从而实现更好的任务级电源管理控制。这使得操作系统能够更好地控制功率/性能权衡，并允许应用程序在每个任务的基础上动态调整存储器和芯片的节能配置，以满足特定的性能要求，同时降低功耗。 通过该项目提供的新功能，可以开发出更丰富的功耗感知应用程序，以在下一代实时环境中提供更好的用户体验。该项目特别关注Web服务器群的需求，这些服务器群的能源和冷却成本很高，并且Web服务提供不同级别的QoS，从而激发了一个平衡性能、QoS要求和能源成本的功耗感知框架。

Increased awareness of power concerns and recent approaches to improveenergy efficiency and heat dissipation in computer systems have notimmediately translated into rich, adaptable, power-aware applications.This lack of effectiveness is particularly evident in power-awarereal-time computing, where efforts to bridge the gap between hardwareand software have generally been limited to developing new schedulersthat operate by modulating a relatively high-level hardware controlsuch as voltage scaling and frequency scaling. The problem with thisapproach is that the hardware controls operate at too gross a level tobe effective in dynamic, poorly-modeled application scenarios.This project develops a feedback-based, control-theoretic approach tooptimize and balance, at runtime, power consumption and real-timeperformance. This approach not only integrates hardware-levelpower-management techniques with real-time and quality-of-service(QoS) constraints, but also integrates a range of hardwarepower-management techniques at different granularities into a unifiedframework that allows better task-level control of power management.This enables finer control of power/performance tradeoffs by theoperating system, and permits applications to dynamically adjust thesystem's and chip's power-saving configuration on a per-task basis tomeet specific performance requirements while reducing powerconsumption. With the new functionality provided by this project, aricher class of power-aware applications can be developed to providevaluable user experiences in next-generation, real-time environments.The project specifically focuses the requirements of web serverfarms where energy and cooling costs are substantial and where the webservices provide differentiated levels of QoS, thus motivating apower-aware framework that balances performance, QoS requirements, andenergy costs.