The Federated Scheduling of Systems of Mixed-Criticality Sporadic DAG Tasks

Under the federated approach to multiprocessor scheduling, each individual task is either restricted to execute upon a single processor (as in partitioned scheduling), or has exclusive access to all the processors upon which it may execute. The federated scheduling of a mixed-criticality collection of independent recurrent tasks is studied here. A model is proposed for mixed-criticality recurrent tasks that extends the (previously-proposed) implicit-deadline sporadic DAG tasks model to account for mixed criticalities. A federated scheduling algorithm for systems of such tasks is presented and proved correct, and a quantitative evaluation of its efficacy derived via the widely-used speedup factor metric.