SF3P: a framework to explore and prototype hierarchical compositions of real-time schedulers

The trend to integrate multiple functionalities on the same (off-the-shelf) hardware has made the selection of the right scheduling algorithm and configuration difficult. This selection requires the designer to validate any scheduling decision already during early design steps on the target architecture, e.g., by using a reconfigurable scheduling framework running in the user-space. In this paper, we first identify the requirements that such a scheduling framework must fulfill. Then, we propose SF3P: an open-source framework that meets these requirements. To this end, we define an interface common to all scheduling algorithms and separate the scheduling algorithm from its low-level implementation. With these features, SF3P can not only prototype a scheduler at high level of abstraction, but also execute the implemented task-set on specific hardware. Furthermore, SF3P can hierarchically compose scheduling algorithms, useful in the mixed criticality domain, and could also be used to explore different scheduling policies in the system optimization phase. We demonstrate these features by implementing SF3P on top of a POSIX-compliant operating system on two different platforms: Raspberry Pi and an Intel Core i7 desktop system.