中文摘要：

时间片轮转算法作为一种经典的调度算法得到了广泛的应用．针对时间片轮转算法的调度策略和时间片长度的选取等问题开展深入的研究，提出了一种改进的动态轮转算法，算法是短作业优先算法、多级队列算法和时间片轮转算法的综合和发展．利用生灭过程理论建立了时间片轮转算法和动态轮转算法的性能模型，分析了两种算法的平均等待时间和平均周转时间，引人性能提高百分比的概念对比两种算法的差异．实验结果和理论分析均表明改进算法的性能优于传统的时间片轮转算法．

英文摘要：

As a classic scheduling algorithm, round robin algorithm has been widely applied. According to the scheduling policy and the selection of the length of time slice for the round robin algorithm, a large number of in-depth studies are carried out. An improved dynamic quantum algorithm is proposed. The algorithm is the devel- opment and integration of shortest job first algorithm, multi-level queue scheduling algorithm and round robin algo- rithm. The performance models of the round robin algorithm and the dynamic quantum algorithm are built by using the theory of birth-death process, including average waiting time and average turnaround time of the two algorithms. The concept of performance improvement percentage is introduced in order to show the differences between the two algorithms. Both theoretical analysis and experimental results indicate that the performance of the improved algo- rithm is better than the traditional algorithm. The advantages of the improved algorithm become more obviously when the number of tasks increase and the rate of service improves.