视频服务器中变比特率视频流的I/O调度

讨论了视频服务器中变化特率（ＶＢＲ）视频流的Ｉ／Ｏ调度问题．其中重点讨论了Ｉ／Ｏ调度中的接纳控制算法．首先提出了Ｂｉ－ＳＣＡＮ磁盘调度算法，并将其应用到ＶＢＲ视频流的Ｉ／Ｏ调度．接着讨论了两种确定性接纳控制算法．确定性接纳控制能提供确保的服务质量，但系统资源的利用率很低．为此提出了一种基于统计复用的统计接纳控制算法，该算法将ＶＢＲ视频数据复杂的统计特性转化为磁盘提交的数据块数量的统计特性，使问题得

I/O Scheduling for VBR Video Streams in Video Servers

Problems of I/O Scheduling for VBR video streams in video servers are discussed in this paper. At first this paper presents a disk scheduling algorithm, named Bi-SCAN. Apply BiSCAN to I/O scheduling of VBR video streams it then suggests two deterministic admission control algorithms, which can guarantee the quality of service. To improve the efficiency of resource allocation, it also proposes a statistic admission control algorithm based on statistic multiplex. The algorithm converts the statistic characteristic of VBR video data into that of the number of data blocks that the disk should render during the service round. This simplifies the problem of admission control of VBR video streams. The simulation results match calculations well, and show that a number of times of concurrent users can be added to the system with an overload probability of 10~(-6) compared with deterministic methods.