Impact of dependable software development guidelines on timing analysis

Abstract

The knowledge of the worst-case execution time (WCET) of real-time tasks is mandatory to ensure correct timing behavior of real-time systems. However, in practice an exact WCET analysis is often intractable due to limitations in computability and analysis complexity of real-size programs. In this paper we analyze how development guidelines for dependable software support and simplify WCET analysis. We investigate three guidelines and their impact on WCET analyzability. DO-178B as a production guide for avionics software expresses requirements that are relevant for timing analysis. The MISRA guidelines include C programming guidelines that improve the WCET analyzability of software. Finally, ARINC 655, a standard for software architectures of avionic systems, provides examples on how to simplify timing analysis already at the design level as early as in system design. The argument of this paper is that careful system design and programming improves the timing analyzability of real-time systems.