Efficient Scheduling Library for FreeRTOS

Sammanfattning: At present, there is a gap between practical implementations of task scheduling on numerous popular Real-Time Operating Systems (RTOSs) and theoretical real-time scheduling. It is difficult to choose what theoretical real-time scheduling concepts to implement when designing a kernel, as theoretical concepts grow and improve over time. Furthermore, the kernel can be kept simpler when offering only simple fixed priority scheduling policy, as advanced scheduling features often require more complex implementation and larger overhead. By offering a real-time scheduling library implemented in user space, the user can choose whether to skip the overhead, or use more advanced theories. At the moment there exists already several scheduling frameworks for FreeRTOS. However, they are either difficult to use, not completely implemented in user space, or not providing various theoretical scheduling policies. An open source scheduling library for FreeRTOS implemented in user space that is user friendly and runs with low overhead, Efficient Scheduling Library (ESFree) is proposed. The proposed scheduling library provides polling server that runs aperiodic and sporadic jobs, dependable timing error detection and handling, Rate-Monotonic Scheduling (RMS), Deadline-Monotonic Scheduling (DMS) and Earliest Deadline First (EDF) scheduling policies to provide theoretical real-time scheduling features to speed up development of complex projects, and make FreeRTOS friendlier to students who have newly studied real-time scheduling.