Protocol-transparent resource sharing in hierarchically scheduled real-time systems

Hierarchical scheduling frameworks (HSFs) provide means for composing complex real-time systems from well-defined, independently analyzed subsystems. To support resource sharing within two-level HSFs, three synchronization protocols based on the stack resource policy (SRP) have recently been presented, i.e. HSRP [1], SIRAP [2] and BROE [3]. This paper describes the first implementation presenting these three SRP-based synchronization protocols side-by-side in a HSF-enabled real-time operating system. We base our implementations on the commercially available real-time operating system µC/OS-II, extended with proprietary support for periodic tasks, idling periodic servers and two-level preemptive scheduling. Moreover, we investigate the system overhead of the synchronization primitives of each protocol. Transparent interfaces allow a protocol to be selected during integration time based on its relative strengths1