Online Scheduling Switch Based on Validity Constraint

In this paper we look at the scheduling problem of adjusting to the fluctuations of a real-time system. We propose to model each variation as a new set of real-time tasks, which would be scheduled by the same or different scheduling policies. Under this model, while each scheduling policy must be able to schedule the corresponding task set, realtime requirements also must be met during the switch for tasks that persist through the switch. In this paper we use validity interval to define the real-time criteria and study the scheduling issues arise during the task set switch. We then get into more details by looking at switching between two polarizing fixed-priority scheduling policies, namely Rate-Montonic scheduling (RMA) and Deferrable Scheduling (DS-FP).