Aspect-Oriented Real-Time Architectures

大动脉项目的目标是通过提取关键路径来提高动态混合临界实时系统的可预测性。这些路径将被转换为它们的静态等效项，并在运行时以时间触发的方式执行。与事件触发的进程相比，时间触发的执行往往会未充分利用资源。因此，将保留混合临界实时系统的乐观执行模型。只有在紧急情况下，实时系统才会根据静态调度执行。同时，第一个资助阶段的结果将推广到动态实时体系结构。特别是，重点将放在具有复杂依赖模式的混合关键系统上。该研究项目将调查实时Linux的几个变种，以及控制工程领域的应用程序。该项目第二阶段的主要重点将是关键和非关键执行路径之间的依赖关系。这些依赖关系可能有潜在的问题，并且可以在系统的所有级别上找到：例如，应用软件可能将非关键舒适功能与关键控制功能相结合，从而导致耦合组件。在操作系统中，缓冲区可用于共享通信堆栈。然而，在动态系统中，通常这种耦合可能是合乎需要的，在运行时的许多可能的执行路径可能导致严重过度配置的系统设计w.r.t.WCET和WCRT。因此，保证执行时间往往会导致从动态实时系统设计中获得的效率的损失。该项目的三个关键活动将在运行时为关键应用核心提供硬保证：分析、裁剪和机制。该项目的基础将是在硬实时约束下设计混合关键系统的现有技术。对于主动脉，通常假定关键路径具有确定性结构，因此它们与非关键路径的耦合可以映射到静态等价。在这个项目的过程中，将仔细检查实时Linux的不同变体提供的简单通信模式的适用性，以确定这些模式是否可以保证安全关键控制应用程序的硬期限，以及在第一个资助阶段开发的静态分析、定制和调度的概念和技术是否适合于此目的。此外，还将在混合关键实时系统的背景下研究耦合实时体系结构、调度和依赖的必要性，以确定实时Linux的设计概念是否适合在运行时切换实时范例。

The goal of the AORTA project is to enhance the predictability of dynamic mixed-criticality real time systems by extracting critical paths. These paths are to be transformed into their static equivalents and to be executed in a time-triggered fashion at run-time. In comparison to event triggered processes, time-triggered execution tends to underuse resources. Therefore the optimistic execution model of mixed-criticality real-time systems will be retained. Only in case of an emergency the real-time system will be executed according to the static schedule. At the same time the results of the first funding phase will be generalized to dynamic real-time architectures. In particular, the focus will be on mixed-criticality systems with complex dependency patterns. The research project will investigate several variants of real-time Linux, as well as applications from the domain of control engineering.The main focus during the second funding phase of the project is going to be on dependencies between critical and non-critical paths of execution. These dependencies may potentially be problematic and can be found on all levels of the system: For example, application software may combine non-critical comfort functions with critical control functionality, leading to coupled components. In the operating system buffers may be used for shared communication stacks. Often such coupling may be desirable, however, in dynamic systems a host of possible execution paths at run-time may lead to dramatically overprovisioned system designs w.r.t. WCET and WCRT. Therefore, guaranteed execution times often lead to a loss of the efficiency gained from the dynamic real-time system design. Three key activities of this project will provide hard guarantees at run-time for the critical application core: analysis, tailoring and mechanisms.The basis for this project will be existing techniques for designing mixed-criticality systems under hard real-time constraints. For AORTA, it will be assumed that in general critical paths have deterministic structure and therefore their coupling with non-critical paths may be mapped to static equivalents. In the course of this project the applicability of the simple communication patterns provided by different variants of real-time Linux will be scrutinized to determine if these can guarantee the hard deadlines of safety-critical control applications, and if the concepts and techniques for static analysis, tailoring and scheduling developed in the first funding phase are suitable for this purpose. In addition the necessity of coupling the real-time architecture, scheduling and dependencies will be investigated in the context of mixed-criticality real-time systems to determine the general fitness of real-time Linux's design concepts for switching real time paradigms at run-time.