Research On Improving Embedded Linux Real-time Performance And Its Application In A Measurement And Control System

With the rapid development of computer hardware and software technology,embedded system has been used in indurstrial measurement and control field step by step because of its low-power,small-size,high-integration prior to general computer. Generally, indurstrial measurement and control system meet to rigid requirement in real-time performace,but most commercial operating systems used currently are foreign and expensive.Especially key technology is mastered by the foreigners .That is dangerous to our national security and our national development is restricted.Otherwise,the other operating systems are too simple,so it is disadvantage to develop complicated embedded system conveniently and agilely. The emergence of embedded Linux operating system based on ARM gives us a chance to change this situation. The embedded system has two aspect advantage ,include ARM about low-power,small-size and high-integration and Linux about free,public source codes and complicated function.So it is accepted widely as a excellent embedded system by most developers.However,common embedded Linux system based ARM does not meet to the requirement in real-time performance about measurement and control system application studied in this papar. Consequently, the author focuses on improvement of real-time performance in embedded Linux system and development of real-time measurement and control system.Firstly,embedded system is introduced in the papar,contrasted and analyzed especially in real-time performance. Otherwise,feasibility and significance are gived about improvement of real-time performance in embedded Linux system.Secondly, ARM series processor is introduced and the evidence that chose S3C2410 processor is gived. And then, principle of pulse width modulation timer as the source of operating system clock is analyzed.Thirdly,principle of system clock,interrupt processing and scheduler in the embedded Linux system based S3C2410 has been studied.And embedded Linux deficiency in real-time performance is summarized.Then key technology improving real-time performance currently is presented . At last, aiming at characteristic and real-time performance requirement of a practical measurement and control system based on embeded Linux, the author of this papar present scheme about Linux system clock granularity modification,reasonable cooperation between software and hardware and adding real-time tasks to kernel.At the same time,non-real-time tasks are as common user application process of embedded Linux operating system.The scheme given above improves the timer resolution of the operating system, when it improves the preemption ability of real-time tasks.But the scheme does not bring CPU too much burden. A real-time measurement and control system is developed based on the scheme. By testing, the measurement and control system has been authenticated to meet demand of real-time performance. And running in reality , the measurement and control system has also good stability.So the scheme is feasible.On the side, ARM embedded chip is core of the hardware platform,part of the papar cite some ground codes analyzed and modified.Because the length of the papar is limited,ARM instruction is not telled of.If you need learn about it detailedly,please read ARM data file.so sorry to your trouble for it.