Real-time Operating System, A Number Of Key Issues Research

Ultra-reliable real-time systems' design consists of real-time theory, reliability technology and the prediction of tasks' characteristic, so it is complicated and time comsumed. The real-time operating system is a new tool for the design of real time system. However, to the fields of industrial-controller and spacecraft system etc. which not only have the hard-real-time requirement, but also the constrained memory, redundant technology, it's an unsolved problem about in the operating systems how to integrity the supports to these specific systems whilst maintain the real-time performance. It's the main purpose of the paper.In this paper, we discuss some key topic on the design of ultra-reliable real-time systems, and carry out a COTS based NMR operating system which is suitable for the critical systems. The major achievement of this paper including:1: The author presents the system architecture and the internal of an RTOS which has been adopted to industrial-controller and spacecraft computer systems. The theory and application of the task management, memory allocation, interrupt and exception, reliable technology, I/O system etc. have been discussed.2. The author proposed a method using the interrupt-delay-queue to reduce the interrupt response time. This method eliminated the influence on the interrupt response time when operating systems have to keep out the probability that interrupt modify the key data simultaneously with the kernel services. Compared with previous technology, this method is much valuable. The author also introduce the realization on X86 and ARM platform and the notification when apply to real system.3. Based on the analysis of the real-time streaming file system model, the author brought forward the square-root buffer allocation algorithm, which is a statistic allocation algorithm and the rates of each IO is known in advance. By reducing the requirement of disk channel utility, the algorithm can improve the throughput of file system. Compared with the proportion allocation algorithm we conclude the algorithm is more suitable for the embedded application such as the real-time data acquisition systems.4. The author presents the approach to the design of fault-tolerant operating system, which based on COTS software and hardware. By introducing theredundant mechanism on multiprocessor systems into the COTS operating system's kernel, our fault-tolerant operating system completely supports the ultra-reliable real-time application. The detailed analysis on the clock synchronization, fault detection and recovery, interactive consistant networking is included.5. we present a new task model for COTS-based NMR systems. By taking full advantage of COTS operating system's kernel function, this model not only satisfies the real-time requirement, but also masks the complexity of NMR system, and gets rid of the defect of previous systems. We also analyzed the real time performance of the tasks that adopt this new model.