Integrating Real-Time Synchronization Schemes into Preemption Threshold Scheduling

Preemption threshold scheduling (PTS) provides prominent benefits for fixed priority scheduling such as increased schedulability, reduced context switches, and decreased memory requirements. Since such benefits allow for scalable real-time system design, we have adopted it into our automatic implementation synthesis method for real-time object-oriented models. In this paper, we present the integration of real-time synchronization schemes into PTS. Specifically, we investigate how to integrate priority inheritance protocols into preemption threshold scheduling such as the basic priority inheritance protocol and the priority ceiling protocol. In our integrated schemes, (1) the preemption threshold, instead of the priority, of a blocked task is inherited when blocking occurs; and (2) priority ceiling, instead of preemption threshold ceiling is used. We also show that our integrated schemes can minimize worst-case context switches and thus is appropriate for the implementation of real-time object-oriented design models.