Research And Design Of Scheduling System Of Operating System On CPS Nodes

CPS (Cyber Physical System), with significant and extensive application prospects, is a new generation of system that is based on the integration of embedded computing, wireless sensor networks and network control technique. The relevant researches on CPS have become the research focus in computer science presently. As a basic element of CPS research, the node operating system is used to support and implement the complex task scheduling and resource management. Owing to a high demand for real-time as well as the extremely limited resources of the sensor node hardware and computing power, the primary goal of building the operating system is to design a scheduling system that meets node resource constraints and scheduling targets.Based on the analysis of existing node operating systems’scheduling mechanisms, this thesis summarizes the objectives of the node operating systems which are real-time, flexibility, concurrency, predictability and low overhead. In order to improve the scheduling flexibility and the ease of programming, this thesis implements a hybrid programming model. On this basis, this thesis designs a hybrid scheduling mechanism that is combined with real-time scheduling theory and CPS’s own characteristics. The design enables the coexistence of event-driven mechanism and multi-threading mechanism. A scheduling strategy called PTS-SRP is also presented for the sake of improving real-time poverty under the lowest overhead.This thesis firstly makes an in-depth analysis of the essential differences between the two models and then a hybrid programming model which combines the two models from the underlying system is presented. Secondly, this thesis builds a hybrid scheduling strategy by encapsulating the event scheduler in a thread package, which is scheduled by the kernel scheduler together with thread scheduler. Meanwhile, in order to fully enhance the predictability and the real-time property of the system, the concept of priority preemption threshold in embedded real-time scheduling mechanism is added to the thread mechanism. Based on this, the thesis set up CPS node operating system task model. Then, this thesis proposes PTS-SRP scheduling strategy to make a reasonable combination of the preemption threshold scheduling algorithm and SRP resource access control protocol according to the in-depth analysis of the two algorithms and the requirements of the nodes operating system. This thesis employs the level-i active period approach to derive PTS-SRP schedulability test formula and proves that the maximum threshold allocation scheme can minimize memory consumption. This thesis implements the maximum threshold assignment algorithm under PTS-SRP scheduling strategy. Finally, through theoretical analysis and experimental evaluation, the thesis compares the performance of scheduling system designed in this paper with the traditional node operating system’s scheduling system. It turns out that the scheduling system designed in this paper basically meets the design goals and the needs of CPS node operating system. It has the value of further research and can be ued in real application.