Schedulability analysis of sporadic tasks with multiple criticality specifications

In a paper that was presented at the recently-concluded Real-Time Systems Symposium, Vestal proposed a new real-time task model that is able to represent the fact that the worst-case execution time (WCET) of a single task may be determined to different levels of accuracy with different degrees of confidence. In systems with multiple criticality requirements - different tasks need to be assured of meeting their deadlines with different levels of confidence - such multiple specifications of WCET may be exploited to obtain better processor utilization. This paper conducts a thorough study of the feasibility and schedulability questions for such multi-criticality real-time task systems when implemented upon preemptive uniprocessor platforms.