CSR: Medium: Collaborative Research: Architecture and System Support for Power-Agile Computing

电池续航时间短是当今智能手机用户最大的抱怨之一，并限制了这些移动设备的变革潜力。硬件组件继续提供新的节能功能，但今天的移动操作系统没有做好充分准备来利用这些新功能。本项目研究新的软硬件协调机制，以更有效地利用现有和下一代硬件节能功能。该项目的重点是通过引入新的操作系统接口和抽象来提高“电源敏捷性”，这是一种衡量系统在硬件组件之间自适应地重新分配能量以满足运行应用程序不断变化的需求的能力。与以前试图直接管理能源的方法不同，该项目探索了测量和管理能源低效的想法，能源低效的定义是实际用于执行任务的超过任务所需最低要求的额外能量的量。分配低效率，而不是能源，解决了以前能源管理方法的许多问题，同时仍然允许操作系统对任务之间的能源使用进行优先排序。通过分配低效率，电源灵活的操作系统可以安全地允许任务使用用户空间调整库直接调整硬件组件，从而允许它们在追求各种不同的能源管理策略的同时，根据不断变化的需求进行跨组件权衡。该项目还通过在两个合作机构开设的关于电力敏捷计算的新课程，将教育与研究相结合。

Short battery lifetimes are one of the top complaints of today's smartphone users and are limiting the transformative potential of these mobile devices. Hardware components continue to offer new energy-saving features, but today's mobile operating systems are ill-prepared to utilize these new capabilities. This project investigates novel hardware-software coordination mechanisms to make use of existing and next-generation hardware energy-saving features more effectively. The focus is improving "power agility", a measure of a system's ability to adaptively reallocate energy between hardware components to meet the changing needs of running applications, through the introduction of new operating system interfaces and abstractions.In contrast to previous approaches that attempt to manage energy directly, this project explores the idea of measuring and managing energy inefficiency, defined as the amount of extra energy actually used to perform a task above the minimum required for the task. Allocating inefficiency, rather than energy, addresses many of the problems with previous energy management approaches while still allowing the operating system to prioritize energy usage between tasks. By allocating inefficiency, power-agile operating systems can safely allow tasks to tune hardware components directly using userspace tuning libraries, allowing them to make cross-component tradeoffs in response to changing requirements while pursuing a wide variety of different energy management strategies. The project also integrates education with the research through a new course on power-agile computing at both of the collaborating institutions.