Tolerant Scheduling Of Real-time Operating System Technology Research And Implementation

Due to the development of real-time systems, more and more safety-critical applications is becoming to use real-time system as the kernel of the control system, and real-time systems become an affectable factor to determine the dependability of the safety-critical application. The dependable techniques of hardware of real-time have become mature enough, which makes the software of real-time systems become the bottleneck of system dependability. As a very important technique for system reliability, software fault tolerance has become a very hot topic.This paper analyzes the factors that influence the system reliability, the causes of those factors, and the basic techniques of system reliability systematically. On the other hand, this paper introduces real-time scheduling in detail. Based on those researches, this paper researches fault-tolerant real-time scheduling deeply. The author thinks that, there are two main obstacles of the development of fault-tolerant real-time scheduling. Firstly, fault tolerance is based on resource redundancy, which will reduce the resource utilization in the absence of faults. Secondly, many fault-tolerance real-time scheduling algorithms, which are reported in literature, have not enough practicability. Neither can these scheduling algorithms schedule real-time tasks with and without fault-tolerant requirements synchronously, nor can schedule period and aperiodic tasks synchronously. So, the research and design of simple and practical scheduling is one of the most important topics of fault-tolerant real-time system.Based on the analysis of the main obstacle of fault-tolerant real-time system, this paper focuses the view to the research of fault-tolerant real-time scheduling, and the main contributions are shown below: Integrating imprecise computing and resource reclaim into fault-tolerant real-time scheduling, and present two new fault-tolerant real-time scheduling algorithms, IC-FT-EDF and RR-FT-RM. The object of those algorithms is to improve the resource utilization in the absence of faults, assure the fault-tolerant ability, and keep the algorithms simple enough. In addition, the authors present a universal fault-tolerance real-time scheduling algorithm, which can schedule various tasks. This paper proves the correctness of those algorithms, give its schedulability bound and analyze its performance. Then, based on real-time operation system CRTOS 2.0, the paper discusses the design of fault-tolerance scheduling module and the achievement of three fault-tolerance scheduling algorithms, which are LP-FT, FT-EDF and FTRM. At last, the fault-tolerance scheduling module is tested. The results show that time and performance cost of fault-tolerance scheduling can satisfy requirements of real-time system.