Design and Implementation of an Adaptive Multilevel Scheduler in a Real-time Operating System

Abstract

The traditional researches on the task scheduling in real-time operating systems were setting the priority for providing service to soft tasks after that can promise meet deadline of hard tasks. Therefore, those scheduling schemes were trying to provide better average meet ratio for soft tasks. In this paper, an adaptive multi-level scheduler is proposed. The proposed architecture applies a tuner, called importance tuner, to evaluate the importance of each task, and to increase or decrease the weight of importance of the task. Then the task is assigned to the multiple EDF schedulers according to its importance weight. In addition to the multi-level EDF scheduler, we have also built a second level RM scheduler to schedule first level EDF schedulers as the normal tasks. Based on μC/OS-II, the proposed scheduling scheme has been implemented. The experimental results show that the proposed scheme can improve the system performance and fit for almost all real-time applications.