Schedulability Analysis for Timed Automata With Tasks

Abstract

Research on modeling and analysis of real-time computing systems has been done in two areas, model checking and real-time scheduling theory. In model checking, an expressive modeling formalism such as timed automata (TA) is used to model complex systems, but the analysis is typically very expensive due to state-space explosion. In real-time scheduling theory, the analysis techniques are highly efficient, but the models are often restrictive. In this paper, we aim to exploit the possibility of applying efficient analysis techniques rooted in real-time scheduling theory to analysis of real-time task systems modeled by timed automata with tasks (TAT). More specifically, we develop efficient techniques to analyze the feasibility of TAT-based task models (i.e., whether all tasks can meet their deadlines on single-processor) using demand bound functions (DBF), a widely used workload abstraction in real-time scheduling theory. Our proposed analysis method has a pseudo-polynomial time complexity if the number of clocks used to model each task is bounded by a constant, which is much lower than the exponential complexity of the traditional model-checking based analysis approach (also assuming the number of clocks is bounded by a constant). We apply dynamic programming techniques to implement the DBF-based analysis framework, and propose state space pruning techniques to accelerate the analysis process. Experimental results show that our DBF-based method can analyze a TAT system with 50 tasks within a few minutes, which significantly outperforms the state-of-the-art TAT-based schedulability analysis tool TIMES.

Formal Modeling of Frame Selection in Asynchronous TSN Communications

“…Based on the work in [26], an improved flow scheduling model is proposed in [27] to reduce search space with a faster exploration. Regarding the schedulability analysis, an UPPAAL-based framework for schedulability analysis of embedded systems is presented in [28], and Sun et al [29] also develop an efficient analysis technique to analyze the feasibility of real-time tasks based on the timed automata models. Besides, Han et al [30] propose an approach for the schedulability analysis of distributed integrated modular avionics (DIMA).…”

Compositional verification of embedded real-time systems

“…A more promising trend is to combine model checking and schedulability analysis. An interesting approach based on timed automata tasks (TATs) is proposed recently in [76], but focuses on single-core scheduling only. The authors of [39] present a realistic ERTS model with sequences of non-preemptible job segments.…”