具有优先级特征的多媒体流的资源管理

本文研究了具有优先级特征的分布式多媒体流的资源管理，提出了一种基于节优先级的资源管理的设计方法，包括资源管理机制，资源管理策略，服务质量（ＱｏＳ）协商调整算法和高优先级节枪占算法，它能够保证稳定的具估优先级特征的多媒体流，能够极大地调度并发的多媒体流，特别是在系统资源不足时，能够最大限度地调度高优先级的多媒体流，并能保证各多媒体流量了的ＱｏＳ。

RESOURCE MANAGEMENT FOR DISTRIBUTED MULTIMEDIA STREAMS WITH CRITICALITY

The guarantees of steady rate of multimedia streams is key issue in resource management of distributed multimedia systems. Many multimedia applications possess character of the criticality that describes the critical extent about media streams. The multimedia stream and its sequentially accessing resources, such as CPU, buffers, I/O and network bandwidth, have been defined. A session with criticality has four states i. e. waiting, running, preempted and closed. This paper presents a prototype of resource management based on the session with criticality including the mechanism of resource management, the strategy of resource management, the algorithm of QoS negotiation and adaptation, and the algorithm of session preemption with high criticality. The prototype can meet steady rate of multimedia streams with criticality. It can maximize not only the total number of concurrent multimedia streams, but also the number of high-criticality multimedia streams scheduled and the QoS of all multimedia streams. System resource manager (SRM)manages a waiting queue of sessions with criticality order. In the prototype, the resource manager will adjust QoS including QoS shrink and QoS extension of all sessions and preempts other sessions when a new session requires resource to schedule high criticality session as possible. Finally, this paper compares performance overhead and effect of session preemption algorithms in client/server model and Windows95/Windows NT environment and shows that the algorithm B is a available algorithm for real-time multimedia systems.