Research On WCET Analysis Of The μC/OS-Ⅱ Real-Time Kernel

One of the major tasks in timing analysis of real-time systems is worst-case execution time (WCET) analysis of tasks or systems. In real-time embedded systems where real-time operating systems (RTOS) are adopted, the timing properties of the system are decided by both the applications and the RTOS. Currently, theμC/OS-Ⅱreal-time kernel is widely applied in many types of embedded systems, but there lacks specific tools or analysis methods to analyze and guarantee the real-time properties of the kernel. Performing WCET analysis of theμC/OS-Ⅱreal-time kernel can help the system developers to have a comprehensive knowledge of its real-time properties. The real-time performance of the whole system can then be evaluated at design time by combing WCET analysis of the real-time kernel and the applications.According to the above requirements, theμC/OS-Ⅱreal-time kernel is analyzed using an open-source static WCET analysis tool - Chronos. A comprehensive quantitative results on the WCET of the system calls are obtained, which is a precise description of the real-time properties of the kernel. The results serve as a foundation of further schedulability analysis, and can also provide with factual data for further improvements in the kernel design. We also conduct an intensive discussion on the main issues of applying static WCET analysis and related tools to analyze RTOSs, including the precision of the analysis, defects of single value WCET analysis, and challenges due to the presence of task switching in multi-tasking systems. The discussion points out some new research directions in WCET analysis. The work of this thesis is a meaningful practice of applying WCET analysis techniques in real-life real-time systems.