Linux下的实时调度算法

Linux实现了实时进程的概念，但并没有提供有效的任务调度支持；另一方面，RM和EDF等传统的优先级调度算法在实时系统中已经得到广泛应用，但它们对于确定优先级所采用的标准比较简单和片面，容易导致紧急型任务的截止期限不能被满足或系统资源不能被充分利用。基于RM和EDF，文中提出了一种新的实时调度算法SBRD，它的优先级根据重要性和紧急性两个重要因素共同确定。实验表明，与RM和EDF相比，SBRD兼具二者的优点，在保证重要任务顺利执行的前提下，优先执行紧急型任务，以满足更多的任务，更充分的利用CPU资源；与原Linux的实时调度相比，SBRD能更有效的调度实时任务。

New Real-Time Scheduling Algorithm Based-on Linux

The concept of real-time task is supported in Linux kernel, but the provided scheduling policies are not effective. On the other hand, some classical priority-based scheduling algorithms, especially like RM and EDF, have been widely accepted and applied to real-time systems. However, their priority usually is determined only by one factor, such as period or deadline, which easily causes to lower resource utilization or much of deadlines not to be guaranteed. Based on RM and EDF, one new real-time scheduling algorithm called SBRD is proposed in this paper, and its most distinct feature is that the priority is determined by both importance for users and urgency. Experiments show that: (1) SBRD is provided with the virtues of RM and EDF, that is, it can make sure more urgent tasks under guaranteeing the more important ones, and make more full use of CPU resource; (2) comparing with the real-time scheduling provided by standard Linux, SBRD is more effective.