Real-Time Operating Systems: Course Development

There are applications, such as industrial machine systems or airplane flight control systems, which require high accuracy that traditional operating systems are not designed to provide. Traditional operating systems are designed for fair usage among many users and many applications. Additionally, they are designed for user interaction and thus intend to provide balanced operation across all applications and users. In time-sensitive cases, however, this balanced operation is not only not required but often detrimental. Real-time applications instead focus on temporal accuracy. There is not a single definitive method of addressing this functional requirement but rather multiple, each to be used depending on the situation. Often, real-time systems run their tasks according to a time schedule in order to fit with other time-sensitive systems. Such systems come in several different forms of varying complexity. The purpose of this paper is to investigate different RTOS implementations and the associated advantages and disadvantages in terms of timing latency and accuracy and to organize this information in an educational format for use in an operating systems course. We will incorporate this material into the curriculum to an existing undergraduate operating systems course. This course is an introduction to operating systems, and thus prior knowledge of process scheduling should not be assumed. The two main implementations that will be discussed here are FreeRTOS and RT Linux, two opposites in terms of complexity and implementation among the real-time operating systems that are available for the Raspberry Pi.