SHF: Medium: Collaborative Research: Ultra-Responsive Architectures for Mobile Platforms

传统的微处理器主要是为持续性能而设计的;它们可以在接近峰值的性能下工作，基本上无限期地工作，直到它们的能源耗尽。在诸如移动的设备等电池和冷却受限的环境中，持续功率（以及因此的峰值性能）必须被限制在至多几瓦，以便设备可以仅使用被动对流来散热。然而，许多交互式移动的应用程序（如手写/语音识别或基于图像的搜索）反而需要响应用户输入的密集计算，从而需要一种新的超响应操作机制：而不是限制峰值功率假设持续运行，系统应该利用热存储来实现短暂的计算突发，大大超过可持续的热限制，而不会过热。 该项目研究一种称为“计算冲刺”的方法，其核心本质是以不可持续的速率进行计算，但只是简短地进行计算，以便温度不会达到不安全的水平。该项目的目标是解决建筑、热、电气和软件障碍通过计算冲刺实现超响应能力。特别是，该项目探讨：（1）架构和内存系统，通过并行冲刺（激活数十个备用功能单元/内核）和升压（过驱动内核以实现单线程性能），同时促进快速爆发;（2）热设计，改善热响应行为，以实现更长时间和更激烈的冲刺;（3）移动优化的电气设计，提供稳定的电源电压，即使电流激增一个数量级或更多;以及（4）软件机制，其明确地管理有限的热预算，并且预测和分级在冲刺期间所需的数据。 该项目包括制造一个实验测试台，以接近未来多核移动设备的计算、热和电能力，并提供短跑的实践经验。项目影响包括：（1）开发和推进提高移动的设备响应能力的技术;（2）将这些发现整合到一个新的跨部门计算机系统设计课程中。

Conventional microprocessors are designed primarily for sustainedperformance; they can operate at near-peak performance essentiallyindefinitely until their energy source is exhausted. In battery andcooling constrained environments such as mobile devices, sustained power(and, consequently, peak performance) must be limited to at most a fewwatts so that the device can dissipate heat using only passiveconvection. However, many interactive mobile applications (such ashandwriting/speech recognition or image-based search) instead call forbursts of intense computation in response to user input, creating theneed for a new ultra-responsive operating regime: rather than limit peakpower assuming sustained operation, systems should instead exploit heatstorage to enable brief computation bursts that greatly exceedsustainable thermal limits without overheating. This projectinvestigates an approach called "computational sprinting", the centralessence of which is to compute at unsustainable rates but only brieflyso that temperatures do not reach unsafe levels.The goal of this project is to address the architectural, thermal,electrical, and software barriers to ultra-responsiveness viacomputational sprinting. In particular, the project explores: (1)architectures and memory systems that sprint via parallelism (activatingtens of reserve functional units/cores) and voltage boosting(overdriving cores for single-thread performance) while facilitatingfast burst onsets; (2) thermal designs that improve thermal responsebehavior to enable longer and more intense sprints; (3) mobile-optimized electrical designs that provide stable supply voltagesdespite current surges of an order-of-magnitude or more; and (4) software mechanisms that explicitly manage limited thermal budgets and anticipate and stage data needed during the sprint. The projectincludes the fabrication of an experimental testbed to approximate thecomputational, thermal and electrical capabilities of a future many-coremobile device and to provide practical experience with sprinting.Project impacts include (1) developing and advancing techniques forimproving the responsiveness of mobile devices and (2) integrating thediscoveries into a new cross-departmental course on computer systemdesign.