CSR---EHS: PITAS: Probabilistic Implementation and Temperature Aware Scheduling of Embedded Software for Energy Efficiency

软实时嵌入式系统，如PDA、便携式多媒体设备、传感器和一些控制系统，需要以一种及时的方式处理数据流，这取决于无法检测到偶尔的执行失败或截止日期未命中的终端用户的满意度。额外的系统资源将提供更好的性能，但最终用户可能不会注意到，也不会奖励这些努力。这一独特的特性为软实时系统的高效设计和实现提供了启示。该项目正在开发一个新的设计框架，以系统地将截止日期的软性转化为更好的资源管理，如减少能源消耗。本研究所追求的策略是分配(离线)满足给定软实时性能要求所需的最小系统资源。也就是说，系统不保证每次执行都能完成，但它将在大量重复中产生足够多的完成，以满足用户特定的完成率。然后在实时执行过程中，片上温度对系统速度和功耗的影响引导频率和电压的动态调整，以开发多处理器系统上未使用的能效能力。本文的工作集中在：(1)建立和验证所提出的概率设计框架的理论基础；(2)开发一套概率多媒体应用基准和原型综合工具软件；(3)对面向消费者的数字信号处理软件进行概念验证。本研究使得一类重要的软实时嵌入式系统的设计和实现具有资源效率，并有望对嵌入式系统行业、未来的监控系统和人们的日常生活产生直接影响。参与该项目的本科生和研究生都学习嵌入式系统设计技能，并获得研究经验。

Soft real-time embedded systems, such as PDAs, portable multimedia devices, sensors, and some control systems, require the processing of data streams in a timely fashion, as determined by the satisfaction of end users who cannot detect occasional execution failures or deadline misses. Additional system resources would provide better performance, but the end users may not notice and will not reward such efforts. This unique feature sheds light on the efficient design and implementation of soft real-time systems. This project is developing a new design framework to systematically transfer such softness of the deadlines into better resource management, such as reduction of energy consumption.The strategy pursued in this research is to allocate (off-line) the minimal system resources necessary to meet the given soft real-time performance requirements statistically. That is, the system does not guarantee the completion of each execution, but it will produce sufficiently many completions over a large number of repetitions to meet the user-specific completion ratio. Then during real time execution, on-chip temperature on system speed and power dissipation guide dynamic scaling of frequency and voltage to exploit unused capacity for energy efficiency on the multi-processor system.This work focuses on (1) building and validating a theoretical foundation for the proposed probabilistic design framework; (2) developing a set of probabilistic multimedia application benchmarks and prototype synthesis tool software; and (3) conducting proof-of-concept prototyping of consumer-oriented digital signal processing software.This research enables the resource-efficient design and implementation of an important family of soft real-time embedded systems and is expected to have direct impact on the embedded systems industry, future surveillance systems, and people's daily life. Both undergraduate and graduate students involved in the project learn embedded system design skills and gain research experience.