A paper entitled “Decoupling Criticality and Importance in Mixed-Criticality Scheduling” has been accepted at the 6th International Workshop on Mixed Criticality Systems (WMC).The paper addresses the need for more expressive task models for mixed-criticality systems by presenting an extension to the well-known mode-based adaptive mixed-criticality model by Vestal. The proposed model allows a task’s criticality and its importance to be specified independently from each other. A task’s importance is the criterion that determines its presence in different system modes. Meanwhile, the task’s criticality (reflected in its Safety Integrity Level (SIL) and defining the rules for its software development process), prescribes the degree of conservativeness for the task’s estimated WCET during schedulability testing.
We indicate how such a task model can help resolve some of the perceived weaknesses of the Vestal model, in terms of how it is interpreted, and demonstrate how the existing scheduling tests for the classic variant’s of Vestal’s model can be mapped to the new task model essentially without changes.