Research And Implementation Of Resource Reservation In Real-Time Operating System

With rapid development of real-time systems, more and more real-time applications not only want the systems to meet their timing requirements, but also hope them provide some functions which used to be supported only by general-purpose operating systems. On the other hand, some desktop environments also need real-time supports. It is quite difficult for existing systems to provide generality and real-time characteristics simultaneously. To solve this problem, we developed the first Linux-based general-purpose real-time operating system ?Red Flag Real-Time Operating System in Mainland China based on the Red Flag Linux. This thesis describes the principles and implementation of resource reservation scheme of our system.In our system, the resource reservation scheme is implemented through resource kernel, which carries out a subsystem providing timely, guaranteed and protected access to system resources. The resource kernel allows applications to specify only their resource demands leaving the kernel to satisfy those demands using hidden resource management schemes. As a result, it simplifies the processes of programming and relieves the burden of programmers. The resource kernel is mainly composed by several mechanisms including reserve description, admission control, reserve scheduling, enforcement and accounting.In this thesis, we provide a programming interface for real-time applications, making them use system resources more conveniently and efficiently to meet their timing requirements. At the same time, while we implement the support to priority inheritance protocols, we introduce two effective synchronization protocols, namely the job conflict protocol and the priority limit protocol, into our reservation-based system, to reduce priority inversion and provide better temporal isolation further. Furthermore, we rearrange the data structures and scheduling algorithms of resource kernel to support Symmetric Multi-Processing.Experiments prove that the resource kernel implemented in this thesis works well in the Red Flag Real-Time Operating System and provides a reliable method to manage system resources. The whole system supports soft real-time quite well, providing generality as well as real-time properties. Most applications running on Linux can run our system without any modifications.