FreeRTOS user mode scheduler for mixed critical systems

Abstract

Real-time systems are applied in the more diverse applications. Most of these applications require specific configurations in order to meet their timing constraints. Real-time Operating Systems offer scheduling policies that produce a certain behavior of the application, difficult to change in order to get a specific and desired dynamic of the system. On the other hand, most real-time applications include tasks with different real-time constraints: from hard real-time tasks to sporadic and soft real-time tasks. Configuring a real-time operating system to get the desire response for each one of these tasks generally involves a deep knowledge of the structure of the kernel and programming it in a privilege mode. In this paper, it is proposed an implementation of a user-level scheduler, easily configurable to adapt the dynamic of the system to the specific features of the application.