Proving Real-Time Capability of Generic Operating Systems by System-Aware Timing Analysis

The static timing analysis of universal real-time operating systems (RTOS) with generically implemented services requires application and system-context–specific knowledge (e.g., number of currently active tasks) to bound overheads. However, due to the missing notion of OS semantics, contemporary timing analysis tools are unable to exploit such information, resulting in failing or overly pessimistic analysis. To tackle this issue, we present our System-wide WCET Analyses framework (SWAN). SWAN's heart is Platina, a parametric source-level annotation language that facilitates the expression and propagation of context information from the application over the OS down to the machine-code level. Through the expression of semantic interdependencies in a unified and reusable way, analysis pessimism is significantly reduced, as we demonstrate by case studies on FreeRTOS, Linux, and a real-world flight-control system. Just as important as our system-aware timing analysis is the tool support for its practical usability. Therefore, we augmented SWAN by a powerful interactive visualization and annotation environment. This enables developers to quickly identify context-dependent spots that require annotation and thus to cope with large implementations associated with universal RTOSs. Eventually, SWAN allows determining if a generically implemented system is real-time capable and thus timeliness is guaranteed.