The Improving Scheme With Real-Time Based On Scheduling System Of Linux2.6

Real-time system is a hot spot in computer application and RTOS(real-time operating system) is the core of real-time system. As the improvement of hardware performance and in order to meet the requirement of real-time application, RTOS needs not only better performance, but also to provide more functions or services,such as GUI, network etc. The commercial RTOSs that exist today is either too simplein funtionalty or too expensive. There is no such a RTOS that is open enough,standard, widely supporting, efficient and also cheap, so many institutes begin research on turning the non-real-time universal operating systems which are functional strong into RTOS. Linux is natualy a good candidate, because it is capable of providing many services, supporting varied hardware, open source, modularized development, compatible with many international and industry standard.Linux is originally designed as an time share operating system. The Linux 2.6 kernel realized the preept of kernel and also realize the 0(1) scheduling arethmetic relate to 2.4 kernel. . But its granularity of timer is rough and its thinking of communicated work fist can't supply hard real-time working of embeded system. There are two ways to improve Linux's real-time performance previously. One way, to separate all kinds of real-time task simply and set absolute priority to the hard real-time task.It will lead to the DMR of soft real-time task increased to a high level.so the performance of soft real-time task is effected enormously,for example,RTALThe other way is to schedule all kinds of real-time task undepartly.It will lead to fatally result due to the soft real-time task effected the hard real-time task.Based on Linux 2.6 kernel and RTAI ,we proposal a schedule structure of resource remainning ,then analyse the reality and technical difficulty of the structure.It used the way of task virtual mapping,let the hard real-time task and soft real-time task can schedule with the same arithmetic of EDF.At the same time ,it can use RTAI to schedule departly,then validate remarkable advantage of the structure relative to general RTAI through testing scheme :It can avoid the DMR of hard real-time not to exceed and decreased the DMR of soft real-time task furthest.To adapt to the schedule way, we use two timer of kernel to realize the high precision timer to run parallel with the timer of Linux kernel and differentiate with the Linux kernel. It realized the high precision processing and improved the stabilization and efficiency of the system.