A Research On Worst-Case Execution Time Estimation Of Object-Oriented Programs

Different from non-real-time systems, the correctness of real-time systems depends not only on the correctness of the produced results, but also on the time when the produce them. The outputs of real-time systems are valid only when they are produced in the predefined time durations. So when constructing real-time system, safe and tight estimations of the worst-case execution time (WCET) of the program is needed.Currently software design practice for embedded systems is still archaic, C and assembler are used on top of a small real-time operating system. Although the performance of this program is good, the development process is so complicated. There is a trend towards using object-oriented programming languages to develop hard real-time applications. The Real-Time Specification for Java (RTSJ) provides a guideline for the implementation of real-time Java platform, however, some object-oriented features, such as dynamic dispatching and dynamic loading, are prohibited from being used in hard real-time systems because they are either unpredictable or unanalysable. In this paper we focus on the WCET estimation method of real-time Java, make some improvements of Javalin architecture from high-level to low-level analysis. A new WCET estimation method of real-time Java based on Java bytecode is proposed. In the high-level analysis, extended the WCETAn class by instruction of new annotation method, which make the method more suitable for the WCET analysis of real-time java program which have some dynamic features; In the low-level analysis, by the introduction of new time-module, make the WCET analysis result more tighter, during the process of create the time-module, the hardware's pipeline and cache feature which may impact the WCET result were considered. The experimental results show that the proposed method can make the estimation of WCET value in Real-time Java tighter and safer.In the end this paper gives experiment results for benchmark program and demonstrates how efficiently and quickly the method can give estimation WCET for real-time java program by comparing to some other methods.