Real-Time Scheduling Algorithms
The module on real-time scheduling algorithms covers fundamental principles and taxonomies crucial for ensuring timely and predictable behavior in embedded systems. It establishes concepts of real-time systems, differentiating between hard, firm, and soft timelines, and delves into various scheduling paradigms including fixed and dynamic priorities. The challenges of resource sharing, especially priority inversion, and techniques for integrating aperiodic tasks while maintaining schedulability are also addressed, culminating in a discussion on multiprocessor real-time scheduling complexities.
Sections
Navigate through the learning materials and practice exercises.
What we have learnt
- Real-time systems must fulfill strict timing constraints, categorized into hard, firm, and soft types based on deadline criticality.
- Different task models (periodic, aperiodic, sporadic) exhibit specific characteristics affecting scheduling approaches.
- Fixed-priority and dynamic-priority preemptive scheduling algorithms (like RM and EDF) have unique properties, advantages, and challenges.
- Techniques for handling aperiodic tasks and preventing priority inversion are essential for maintaining system reliability and performance.
Key Concepts
- -- Hard RealTime Systems
- Systems where missing a deadline results in catastrophic failure.
- -- Firm RealTime Systems
- Systems where missing a deadline degrades quality but does not lead to complete failure.
- -- Soft RealTime Systems
- Systems where deadline misses are tolerable and cause only a degradation in performance.
- -- Preemption
- The ability of higher-priority tasks to interrupt lower-priority tasks during execution.
- -- Priority Inversion
- A situation where a higher-priority task waits for a lower-priority task, leading to deadline misses.
- -- Rate Monotonic Scheduling
- A fixed-priority scheduling algorithm where tasks are prioritized based on their periodic intervals.
- -- Earliest Deadline First Scheduling
- A dynamic-priority scheduling algorithm that selects tasks based on the nearest deadline.
Additional Learning Materials
Supplementary resources to enhance your learning experience.