Schedulability Analysis of Mixed-criticality Systems with Multiple Frequency Specifications

In mixed-criticality systems functionalities of different criticalities, that need to have their correctness validated to different levels of assurance, co-exist upon a shared platform. Multiple specifications at differing levels of assurance may be provided for such systems; the specifications that are trusted at very high levels of assurance tend to be more conservative than those at lower levels of assurance. Prior research on the scheduling of such mixed-criticality systems has primarily focused upon the case where multiple estimates of the worst-case execution time (WCET) of pieces of code are provided; in this paper, a model is considered in which multiple estimates are instead provided for the rate at which event-triggered processes are executed. An algorithm is derived for scheduling such systems upon a preemptive uniprocessor; the effectiveness of this algorithm is demonstrated quantitatively via the speedup factor metric.