Interference Constraint Graph — A new specification for mixed-criticality systems

Current research in mixed-criticality systems assumes that any task of lower criticality levels can be dropped at anytime in order to guarantee the schedulability of tasks of higher criticality levels. However, in an industrial mixed-criticality system, tasks may interfere with each other only under certain scenarios. Currently a designer does not have any means to specify or control this. The paper proposes the Interference Constraint Graph (ICG) which specifies the allowed interferences between tasks. The new specification formalism generalizes and can easily express many of the existing mixed-criticality scheduling conditions. In spite of its generality, we show that standard fixed-priority scheduling can be efficiently applied. Experiments demonstrate that the ICG model enables systematic reduction of the number of tasks that can be dropped.