Research On Hard Real-Time In μCLinux

With the development of computer technology and the expanding of application field of real-time system, the scale and complexity of system is increasing, the specific application is various types real-time application, including the situation of hard real-time applications, soft real-time applications and non real-time applications which are coexisting in one system is getting more and more popular. Most of the Embedded System is working in the real-time environment; the attention which system gives is not the validity of the computing results on the logics, in addition, the timeliness of outputting results.Embedded Real-Time Operating System plays an important part in the embedded environment on real-time character, however, the currently popularized Embedded Real-Time Operating System (Window CE, VxWorks) is surprisingly expensive, and moreover open source is unobtainable. Therefore, modification to the open source oriented and less real-time supported Embedded System is becoming the important studying direction.Based on the detailed analyzing of real time characterized kernel of the Embedded Operating System, this article illustrates disadvantage ofμCLinux which is real-time supported through specific task responded model, put forward dual kernel framework(RTAI+μCLinux) to reformμCLinux, and design the project. There are two stages in the project.Firstly, study the Adeos theory model thoroughly in the first stage, and accomplish HAL(Hardware Abstract Level), which manage and schedule the dual kernel. Secondly, study RTAI kernel deeply, tailor and transplant about it, meet the requirement of the real-time altering.In the second stage, aiming at the existing problem in the dual kernel framework, propose the soft-hard real-time task combined scheduling model, implement the combined task scheduler adopt the CBS algorithm based on Server strategy. According to the two different situations of hard real-time and mixed real-time, build the testing platform and perform the test. The testing results show that reformedμCLinux with dual kernel not only meet the need of hard real-time task, but also enhance the whole performance and meet the requirement of mixed task scheduling while the hard real-time task executing through allocating part of CPU bandwidth to soft real-time task.