Realistic scheduling models and analyses for advanced real-time embedded systems

Abstract

Focusing on real-time scheduling theory, the thesis demonstrates how essential realistic scheduling models and analyses are when guaranteeing timing correctness without over-provisioning the necessary system resources. It details potential pitfalls of the de facto standards for theoretical examination of scheduling algorithms and schedulability tests, namely resource augmentation bounds and utilization bounds, and proposes parametric augmentation functions to improve their meaningfulness. Considering uncertain execution behaviour, systems with dynamic real-time guarantees are introduced to model this scenario more realistically than mixed-criticality systems, and the first technique that allows to precisely calculate the worst-case deadline failure probability for task sets with a realistic number of tasks is provided. Furthermore, hybrid self-suspension models are proposed that bridge the gap between the over-flexible dynamic and the over-restrictive segmented self-suspension model with different tradeoffs between accuracy and flexibility.