Linux-based Embedded Real-time Research And Improvement

The real-time controling embedded product, not only has exhibited the magnificent foreground for the embedded market, also challenged the embedded technology, specially to the embedded real-time operating system(RTOS). The RTOS is the platform of the embedded application software, its design faces kinds of hardwares, and provids the application programming interface(API),and the RTOS must have the high real-time performance, to satisfies the real-time response.Because the Linux operating system opens source code and the high reduction causes attention of the embedded real-time domain. But Linux is one kind of general time-sharing system, this has limited it in the embedded real time system application, So must make the real-time improvement, to satisfies the real-time performance request.This article first has analyzed the Linux operating system code, specially has analyzed the scheduler subsystem, has pointed the cause that performance of real-time is not strong: The kernel could not preempt has caused the very big Scheduler-latency, and used two kind of methods: Low Latency Patch and Preemption Patch, to makes the improvement to its Scheduler-latency ,and give the realization, carries on the test with realfeel.c to these two kind of methods, the test result indicated that the performance had the distinctly improvement. Simultaneously I according to the real-time scheduling theory, has given the EDF scheduler algorithm frame in the Linux system, to enhances the Linux system's real-time performance.