Incorporating scenarios and heuristics to improve flexibility in real-time embedded systems

Flexibility, the ability to adapt to change, is important for real-time systems. As in any type of system, changes arise from maintenance, enhancements and upgrades. These changes are only feasible if timing requirements imposed by the real-time nature of the system can still be met. A flexible design will allow tasks to be added without impinging on other tasks, causing them to miss deadlines. The design space for these systems consists of many configurations describing how tasks and messages are allocated to hardware and scheduled on a hardware platform. Heuristic search is a well recognised strategy for solving allocation and scheduling problems but most research is limited to finding any valid solution for a current set of requirements. The technique proposed here incorporates scenario based analysis into heuristic search strategies where the ability of a solution to meet a scenario is included as another heuristic for the changeability of a system. This allows future requirements to be taken into account when choosing a solution so that future changes can be accommodated with minimal alterations to the existing system.