The Generalized Graph Real-Time Task Model

Safety-critical real-time embedded systems are becoming difficult to model and analyze as they accommodate more and more functionalities, and they rely on more and more complex HW and SW implementations. One of the main difficulty with such systems is to find the right coupling between the task model and the analysis method. Indeed, if the task model is too simple it may add pessimism to the result of the analysis, and it may not be possible to prove the correctness of the systems. If the model is too complex, the analysis may be not efficient enough to be usable; or worst the model may have an incomplete method only or no method at all, so the system cannot be analyzed. Finding, the right couple task model analysis method is a balance between expressiveness and analysis efficiency. In this article, we introduce a new graph real-time task model (noted GGTM) which has been used for several years for the deployment and the analysis of different embedded systems. We discuss its expressiveness compared to the literature and demonstrate its advantages. We also, present a decidable and efficient, exact schedulability analysis.