|
With the development of computer, as well as communication and consumer electronics, real-time systems are widely used in many fields including aerospace, military, industrial control and so on. These applications require predictability and real-time, of which the performance of real-time operating system(RTOS) has an important effect on the whole system. RTOS is now a hot topic.Linux, with its cheap, stable, good portability and other advantages has popularized and developed rapidly. Linux as a divided-time OS mainly aims at fairness and system throughput, it has some defects in real time. Compared with the Linux 2.4 kernel, Linux 2.6 kernel uses some new techniques, such as preemptible kernel, O(1) scheduling algorithm. But there is some lacks in terms of real time, need to be improved.Firstly, the text from the overall height introduce Linux system, including the Linux operating system structure and the kernel structure, composition and so on. especially analysize the scheduling algorithm, preemption of the kernel, the priority inversion problem and so on. on this basis, analysizing some decefects in real time of Linux operating system. Firstly, For external interrupt lead kernel to stop execute real-time task and execute interrupt handler. Which lead to a real-time task execution time of uncertainty. For this, the text introduce the idea of interrupt threading. the interrupt as a kernel thread is given a priority, with the task of running compared to determine the execution right Secondly, In scheduling system, real-time process prority is no change with times and environment. For this the text introduce Least Slack Time First algorithms to improve existing scheduling policy.After testing and certification, these improvements enhance the real-time of Linux operating system to some extent.
|