Research Into Real-time Character Of Embedded Operating System Based On Linux

With the rapid progress of information and networking technologies, the development of embedded systems, as one of the most important IT industries for the 21~st century will possess numerous commercial markets. In this situation, Linux system which has made great success in server applications will obtain further development and find wide applications in the embedded industry, with the advantages of low cost and powerful functions etc. The research on embedded Linux systems has recently received many attentions and becomes very active.The paper mainly discusses the research and implement of Linux hard real time performance in order to meet the needs in embedded field. Firstly, the paper introduces embedded system, real time operation system of embedded system and embedded Linux, deeply analyses advantages of Linux serving as embedded operation system and shortcomings in the aspect of hard real time performance. On the basis of study, the paper compares various scheme of embedded Linux implementing hard real time performance currently. We study various of feasible of reconstructing measure already existing. This work provides a strong background for our future research and development.Secondly, we deeply analyse the source code of Linux kernel, especially process management and memory management, and master the framework and the idea of implement. We establish the reconstructive scheme. We solved the problems of the coarse-grained timer of Linux by increasing its temporal granularity. Realizing of coarse-grained timer has been explained under two kinds of modes. Through eliminating the virtual memory of Linux, new system compared with the old one has a clear improvement in steadiness and real-time character. We research the algorithm of RMS, EDF and multilevel feedback queue in theory, and apply the EDF and RMS scheduling algorithm into Linux operating system. Two real-time schedulers based on Linux, EDF and RMS are designed. Real-time system of adopting this scheme, usercan choice an appropriate strategy on the basis of their need. It can be used in many fields. After testing, the ameliorated system can resolve the problem of real-time character. It can be performed better in hard real-time field.At last, some other key techniques of Linux real-time method and opinions are put forward. Through changing corresponding method, it must be make a large effect on embedded domain. We view the direction of embedded Linux for the future.