Time-Oriented Modeling and Analysis for Real-Time System under Variability

Abstract

With the advent of MDA, there is an urge to analyze the time performance in real-time systems under various design decisions at the very early stages of design. With the wide application of customized real-time operating system (RTOS) based on a microkernel, we propose a time-oriented modeling and analysis approach for real-time systems based on RTOS at the early stages of design. According to the commonality and variability in the system, a modeling approach for analyzing the time under variable design decisions is presented. These design decisions include various hardware environment, user-level services adopted in RTOS, and the task settings. In the analysis approach, a timing tree with the operating and timing rules is defined and used based on the time annotations of the basic system call of RTOS and worst-case execution time (WCET) of the functional block in a task to analyze the execution time. The modeling and analysis approach proposed is capable of analyzing new decisions without any changes in the model, which is helpful to find the best design decision to improve the real-time in the system. Finally, a real-life aircraft landing control system is taken as an example to evaluate this approach.