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, SIRAP and BROE. 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 strengths.