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、共享资源的多核系统、支持挂起的多处理器同步协议等的交互，作业可能会挂起。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，并通常会导致性能/可调度性的显著下降。尽管过去在解决自我暂停任务系统方面取得了一些看似积极的结果，但由提案申请人陈建佳教授领导的一项最近的调查表明，2013年前的很大一部分文献(以及大部分结果)存在严重缺陷。由于2013年前的大多数结果实际上是有缺陷的(或证据不完全的)，自2015年以来，实时嵌入式系统中的自挂起任务模型的研究重新启动。本项目旨在研究健壮可靠的基本算法和分析，以谨慎地缓解(通过安全可靠的执行/挂起实施)和分析(通过严格的可调度性测试)现代实时嵌入式系统中自挂起行为的影响。目标系统是具有实时要求的安全关键系统。由于自暂停行为会引入高度的复杂性，因此需要新的调度策略或修改现有的调度策略。我们的项目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，以灵活地适应自暂停行为，而不会在考虑最坏情况下的定时行为时引入太多悲观情绪。通过本项目中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，以便从控制器、通信和计算的角度进行进一步的优化。

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.