Real-Time Scheduling Theory and Ada
Abstract
The Ada tasking model represents a fundamental departure from the cyclical executive model. Indeed, the dynamic preemption of tasks at runtime generates non=deterministic timelines that are at odds with the very idea of the fixed execution timeline required by a cyclical executive. From the viewpoint fo real-time scheduling theory, an Ada task represents a concurrent unit for scheduling. As long as the real-time scheduling algorithms are supported by the Ada runtime and the resource utilization bounds on CPU, I/O drivers, and communication media are observed, the timing constraints will be guaranteed. Even if there is a transient overload, a fixed subset of critical tasks can still meet their deadlines as long as they are schedulable by themselves. In other words, the integration of Ada tasking with analytical scheduling algorithms allows programmers to meet timing constraints by managing resource requirement and relative task importance. This makes Ada tasking truly useful for real-time applications while also making real-time systems easier to develop and maintain.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1988
- Accession Number
- ADA205048
Entities
People
- John B. Goodenough
- Lui R. Sha
Organizations
- Carnegie Mellon University