Extending the POSIX-Compatible Application-Defined Scheduling Model

The application-defined scheduling model allows the implementation and use of different scheduling policies in a way compatible with the scheduling model defined in POSIX. The new scheduling policies are integrated into a real-time operating system without modifying its internal structure. In this paper, we discuss the application-defined scheduling model and propose some extensions to it. Particularly, we propose an extension to provide flexibility in defining application-defined synchronization mechanisms, in order to schedule efficiently aperiodic tasks using shared resources. Furthermore, an extension to the application-defined scheduling API is proposed to simplify the use of application-defined schedulers and to integrate new functionalities to the real-time applications developed using the proposed model. The extensions shown in this paper have been implemented in RTLinux and results of the evaluation of the implementation are presented.