Suspension-Aware Designs and Analyses for Real-Time Embedded Systems

在计算系统中，由于与外部I/O设备或加速器、具有共享资源的多核系统、可感知挂起的多处理器同步协议等的交互，作业可能会挂起自己。对于实时嵌入式系统，自挂起行为会对实时任务的可调度性产生负面影响，通常会导致性能/可调度性的大幅下降。尽管过去在解决自暂停任务系统方面已经报道了一些看似积极的结果，但最近由提案申请人陈建佳教授领导的一项调查表明，2013年之前的很大一部分文献（以及这些结果中的大多数）存在严重缺陷。由于2013年之前的大多数结果实际上存在缺陷（或证明不完整），因此自2015年以来，对实时嵌入式系统中自挂起任务模型的研究已经重新启动。该项目旨在研究强大而坚实的基本算法和分析，以仔细减轻（通过安全和健全的执行/暂停执行）和分析（通过严格的可调度性测试）自暂停行为在现代实时嵌入式系统中的影响。目标瞄准系统是具有实时性要求的安全关键系统。由于自挂起行为会引入高度的复杂性，因此需要新的调度策略或对现有调度策略进行修订。本课题旨在为调度理论和相应的可调度性分析提供根本性的突破，在考虑最坏时序行为时，灵活地适应自悬行为，而不引入太多的悲观主义。通过本项目提供的调度策略和可调度性测试，我们的目标是为实时系统设计人员提供工具，以便通过考虑控制器、通信和计算的角度来进一步优化。

In computing systems, a job may suspend itself, due to the interactions with external I/O devices or accelerators, multicore systems with shared resources, suspension-aware multiprocessor synchronization protocols, etc. For real-time embedded systems, self-suspension behavior negatively impact the schedulability of real-time tasks and typically cause substantial performance/schedulability degradation. Even though some seemingly positive results have been reported for tackling self-suspending task systems in the past, a recent investigation led by the proposal applicant, Prof. Dr. Jian-Jia Chen, indicates that a significant portion of the literature (and also the majority of these results) before 2013 has been seriously flawed. Since most results before 2013 were in fact flawed (or with incomplete proofs), the investigation of self-suspending task models in real-time embedded systems has been restarted since 2015. This project intends to investigate robust and solid fundamental algorithms and analyses to carefully mitigate (via safe and sound execution/suspension enforcements) and analyze (via tight schedulability tests) the impact of self-suspending behavior in modern real-time embedded systems. The targeting systems are safety-critical systems with real-time requirements. Since the self-suspending behavior can introduce a high degree of complexity, new scheduling strategies or revisions of existing scheduling strategies are required. Our project intends to provide fundamental breakthrough in the scheduling theory and the corresponding schedulability analysis to flexibly accomodate the self-suspension behavior without introducing much pessimism when considering the worst-case timing behavior. With the scheduling strategies and schedulability tests provided in this project, we aim to offer tools for real-time system designers so that further optimizations by considering the perspectives of controllers, communications, and computation are possible.