具有公平带宽分配高效实时磁盘调度研究

发布时间：2018-12-10 11:42

【摘要】：多媒体服务器需要一个实时磁盘调度算法来为具有软实时要求的连续多媒体流服务。由于数据传统的磁盘调度算法没有考虑磁盘请求的实时性,因此需要对传统的磁盘调度算法SCAN进行改进以使其能够应用于多媒体服务器的磁盘请求。本文提出一个新的实时磁盘调度算法,称之为公平带宽分配电梯调度SCAN-FBD(SCAN with Fair Bandwidth Distribution),能够为可变码率编码的流提供质量保证,并且为非周期任务限制了响应时间。SCAN-FBD算法将实时流分为保证任务和可选任务。只有当一个流中的保证任务被满足时,接纳控制才会接纳这个流。通过带宽预留和接纳控制机制,SCAN-FBD算法能够为已经处于服务中的多媒体流提供质量保证,为非实时任务也预留了带宽以保证非实时任务具有合理的响应时间。质量协调机制使得系统能为更多的磁盘请求服务。负责监测与动态调整磁盘带宽分配机制能够根据实时请求与非实时请求的带宽需求,动态调整磁盘带宽在两类任务间的分配,更合理地利用磁盘带宽并进一步提高磁盘吞吐率。SCAN-FBD采用一种积极策略在运行时动态回收未用的带宽。被回收的带宽被用于为可选任务或者更多的非实时任务服务。为了评价所提出的SCAN-FBD算法的性能进行了一系列的实验。实验结果显示,SCAN-FBD比其他算法明显为实时流提供了更好的质量,同时也大大缩短了非实时任务的响应时间,是一个高效、灵活的实时磁盘调度算法。
[Abstract]:Multimedia server needs a real-time disk scheduling algorithm to serve continuous multimedia streams with soft real-time requirements. Because the traditional disk scheduling algorithm does not consider the real-time of the disk request, it is necessary to improve the traditional disk scheduling algorithm (SCAN) so that it can be applied to the disk request of the multimedia server. In this paper, a new real-time disk scheduling algorithm called Fair bandwidth allocation Elevator scheduling (SCAN-FBD (SCAN with Fair Bandwidth Distribution),) is proposed, which can provide quality assurance for variable bit-rate encoded streams. And the response time is limited for aperiodic tasks. The SCAN-FBD algorithm divides real-time flows into guaranteed tasks and optional tasks. Admission control accepts a stream only if the guaranteed task in the stream is satisfied. By means of bandwidth reservation and admission control mechanism, the SCAN-FBD algorithm can provide quality assurance for multimedia streams that are already in service, and also reserve bandwidth for non-real-time tasks to ensure a reasonable response time for non-real-time tasks. The quality coordination mechanism enables the system to serve more disk requests. Monitoring and dynamically adjusting the disk bandwidth allocation mechanism can dynamically adjust the disk bandwidth allocation between the two types of tasks according to the bandwidth requirements of real-time and non-real-time requests. Using disk bandwidth more reasonably and further improving disk throughput, SCAN-FBD adopts an active strategy to dynamically recover unused bandwidth at run time. The recovered bandwidth is used to serve optional tasks or more non-real-time tasks. A series of experiments were carried out to evaluate the performance of the proposed SCAN-FBD algorithm. Experimental results show that SCAN-FBD provides better quality for real-time stream than other algorithms, and also greatly reduces the response time of non-real-time task. It is an efficient and flexible real-time disk scheduling algorithm.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP333.35

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