Study And Design On Real Time About Embedded Linux

As a category of UNIX operating system, Linux obtains some features like stability and high efficiency which are features of UNIX operating system; meanwhile, the capabilities of Linux become more progress and mature. Compare with other operating systems, Linux can revise its source codes according to different demands, support some architecture platforms and customize some functions. These features make Linux have a potential prospect in real-time application.But as a general operation system and Linux is not a really real time operation system, so it is only named soft real time and is not hard real time operation system. Its standard kernel has not supported event priority and preempted real time, at the same time, it has not provided predictable response time which has been needed for most of embedded application. So it is important to extend its real time performance during developing embedded Linux system.But there has three apparent shortcomings as a general operation system, i.e., long interrupted lock time, unpreempted kernel, fair schedule policy, so this paper will discuss next several parts to improve its real time performance in favor of developing the embedded system:Unpreempted kernel: this paper puts forward the modifying ideas from preempt lock, mutex lock, interrupt process and shedule function. Schedule algorithm: it set up a new shedule model and raises a new shedule algorithm from the current shedule bug.Threaded interrupt:study threaded interrupt and threaded interrupt is applied to the 2.6 kernel.Scheduler design:this paper designs and realizes a real time scheduler based on EDF idea. After some tests,it proves that the new real time scheduler has better effect in real time performance than unimproved Linux,and the new one can be used well in real time field.