Schedulability Analysis for a General Model of Mixed-Criticality Recurrent Real-Time Tasks

In their widely-cited survey on mixed-criticality systems, Burns and Davis describe a very general model for representing mixed-criticality sporadic tasks. In this general model multiple estimates, at differing levels of assurance, are specified for each of the three parameters -- worst-case execution time (WCET), relative deadline, and period -- characterizing a 3-parameter sporadic task. The preemptive uniprocessor scheduling of systems of such tasks is considered. A scheduling algorithm is presented, proved correct, and quantitatively characterized via the speedup factor metric for dual-criticality systems of such tasks. To our knowledge, this is the first work to conduct any form of analysis of task systems that are represented using this general model.