Non-preemptive scheduling and schedulability condition for embedded systems with real-time constraints

After a state of art on classical scheduling and on real-ime scheduling, particularly, allowing to define the notions used afterwards and after motivating a new real-time constraint of latency, we propose a model which describes the real-time systems with precedence,
periodicity and latency constraints.
In this model, the precedences are defined using a directed acyclic graph. In the monoprocessor case, we study three problems of scheduling: systems with precedence and periodicity constraints, systems with precedence and latency constraint and systems with precedence, periodicity and latency constraints. For each problem we study the relation between the precedences and the periodicity, respectively the latency, we give schedulability conditions and we propose scheduling algorithms which are proved optimal (if there is a schedule, the algorithm will find it). For the
multiprocessor case the architecture is defined by a non-oriented graph. We study three multiprocessor scheduling problems in the same cases as in monoprocessor, taking into account communication times . For each problem the model takes into account the communications . We prove that each problem is NP-hard and we propose heuristics. The performances of each heuristic are compared to those of an exact algorithm of type branch and bound, using numerical simulations.