Research And Improvement Of Linux And RTAI Based Real-time Operating System

Nowadays, there are many tasks which are relevance with the time factor. Their correctnesses of the results are not only depend on the correctness of the process logic, but also depend on the the time that the result shows up. These tasks are defined as Real-time tasks. Real-time system emerges as the times require. Real-time system is widely used in many fields like military and home application. Realt-time operating system (RTOS) is the core of it. With the rapid upgrades of hardware, the effectiveness of RTOS is not the only criteria, and more functions are required: graphic interface, network communication and etc. Many kinds of commercial RTOS were developed to meet the needs. But these RTOS are either too simple in function or too expensive. Thus, a standardized, open-sourse, widely hardware supported, effective and low-price RTOS is in urgent need. And many instituitions are engaging on developing this RTOS.A major concern in the field was put on Linux for it has the advantages like open-souce, wide hardware supporting, stable and effective kernel, perfect and numerous developing tool chains. But as a universal time-devision operating system, the principle of tasks scheduling of Linux is fairness, so this restricts the application of Real-time on it. Hence, enhancement of Linux should be made to meet the the requirement of the Real-time tasks.The main content of this dissertation is:①researched Linux 2.6 kernel's tasks schedule including the structs of task, schedule mechanism; researched important schedule functions; researched the advantages and disvantages of the Real-time application of Linux.②researched the system architecture of RTAI, schedule mechanism; analyzed two schedule algorithms that were used in RTAI: RM and EDF. By means of the research, pointed out the shortcoming of EDF schedule algorithm and RTAI tasks organizing method.③proposed to extend RTAI by bringing LLF and O(1) schedule algorithm into RTAI; implemented the enhancements and constructed a Real-time Linux operating system using Linux and RTAI.④introduced the criteria of testing RTOS, tested the correctness of schedule and performance of the enhanced Real-time Linux operating system. Then the test results were analyzed. In summary, this dissertation enhanced Linux and RTAI based Real-time operating system by improving EDF schedule algorithm and task organizing method of RTAI. Implemented the enhancements and constructed a RTOS, successfully solved the problem of numerous tasks'failure to run under heavy-load circumstance. Both the theoriotic analyse and the test result showed that the enhancements are correct and efficient and RTAI's real-time capability was indeed improved.