Application And Research On The IPC Measure And Control System Based On Linux

The RTOS(Real-Time Operation System) holds the balance in a real time measuring and control system, and sometimes its performance determines whether a measure and control system can reach the expectation. A few big companies in the world firmly dominate the key technique of a RTOS. The Linux gave us a hope to change the situation. Under this background, this thesis expounds my research: applying Linux to an IPC measuring and control system, which is centered on improving real-time performance.Linux is designed for a workstation and its process schedule mechanism is aimed to optimize the ordinary circumstance, so it must be rebuilt to improve real-time performance if it is applied in a real-time system. Generally there are two ways to reach the goal. One is the POSIX(the "Portable Operating System Interface"), the other is the bottom programming. In the former method, the POSIX.1b function that has a good real-time performance is transplanted into the Linux. There are a lot of difficulties in using this method, so its prospect is not brilliant. In the latter method, a principle must be complied: the Linux kernel is modified without much change and some essential parts that leads to bad real-time performance is improved. By this means, RTLinux, RTAI and KURT get a good real-time performance, and this means is also in application to my research. In this thesis the author brings forward a new real-time scheme based on the current real-time productions of Linux. In the scheme, not only the RTLinux's double kernel structure and its virtual interrupt are adopted, which make the standard Linux process as the lowest priority one in the real-time kernel, but also the 8254 is set to work in the One-shot model by using the KURT's UTIME package, which improves the clock frequency of the OS and reduces the CPU's extra burden. The real-time kernel of the new scheme consists of a scheduler that is designed by a custom according to the scale of a concrete system and the combination of the virtual interrupt and the UTIME package. In addition, the author brings forward an idea: the real-time kernel and the standard Linux kernel has its own OS clock; the author studies the arithmetic about the initial value for 8254 while 8254 is working in the One-shot model, which has the instructive meaning in application. Finally, as an example of Linux application and the verification of the new scheme, a scheduler designed by author schedules a lot of real-time tasks in a concrete IPC measuring and control system, the IPC system runs perfectly well.