Model-based schedulability analysis of safety critical hard real-time Java programs

Abstract

In this paper, we present a novel approach to schedulability analysis of Safety Critical Hard Real-Time Java programs. The approach is based on a translation of programs, written in the Safety Critical Java profile introduced in [21] for the Java Optimized Processor [18], to timed automata models verifiable by the Uppaal model checker [23]. Schedulability analysis is reduced to a simple reachability question, checking for deadlock freedom. Model-based schedulability analysis has been developed by Amnell et al. [2], but has so far only been applied to high level specifications, not actual implementations in a programming language. Experiments show that model-based schedulability analysis can result in a more accurate analysis than possible with traditional approaches, thus systems deemed non-schedulable by traditional approaches may in fact be schedulable, as detected by our analysis.Our approach has been implemented in a tool, named SARTS, successfully used to verify the schedulability of a real-time sorting machine consisting of two periodic and two sporadic tasks. SARTS has also been applied on a number of smaller examples to investigate properties of our approach.

Symbolic execution and timed automata model checking for timing analysis of Java real-time systems

“…In recent years, several analysis tools for SCJ have been put forward including WCA [22], SARTS [23], TetaJ [24], and TETASARTS [25]. Characteristic for these is that they rely on reconstruction of the control-flow graph (CFG), which characterizes all possible execution paths of the program.…”

“…Many model-based timing analysis tools such as META-MOC [7] for executables, and WCA [22], TetaJ [24], SARTS [23], and TETASARTS [25] for Java rely on processing the program to build a CFG and enumerating the execution paths over the CFG. The paths are then translated to a modeling formalism, e.g., timed automata, and timing analysis is then formulated as a reachability problem using an appropriate logic such as TCTL.…”

“…It is agnostic to the execution environment of the real-time system and relies on a specification of the tasks. SYMRT follows the approach of SARTS [23] and TETASARTS [25] relying on TIMES for its theoretical framework but, as opposed to TIMES, maintains a correspondence between the analyzed code and the model.…”

Hardware Support for Embedded Java

“…JOP is also in use in several industrial applications [49,35]. Furthermore, the WCET friendly architecture of JOP enabled development of several WCET analysis tools for Java [19,7,23]. The WCET analysis tool WCA is part of the JOP source distribution [58].…”

Schedulability Analysis Using Uppaal: Herschel-Planck Case Study

“…An approach of [4] provides Java code transformation into Uppaal [2] timed-automata for schedulability analysis. Similarly, we use the model-checking framework provided by Uppaal, where the modelling language is extended with stop-watches and C-like code structures allows to express preemption, suspension and mixed resource sharing using two different protocols, in a more intuitive way without a need for more complex model transformations or workarounds.…”