Web集群服务器中基于多类限定延迟的区分服务机制

针对Web集群服务器中的区分服务机制存在资源利用率不足的问题，提出了一种基于多类限定延迟的区分服务（MCDDS）机制．该机制使得低优先类的用户请求可以占用高优先类的用户请求未使用的资源来提高资源利用率．通过结合优先级调度策略和排队论，建立了各优先类的用户请求实时检测参数与限定延迟间的数学公式，以实现动态的接纳控制和分发策略，达到控制各优先类的用户请求延迟的目的．对MCDDS与现有的机制进行了模拟实验，结果表明，在高负载下系统的资源利用率提高了61％，且MCDDS机制能控制各优先类的用户请求延迟在限定的延迟范围之内．

Differentiated Service Mechanism Based on Multi-Class Bounded Delay for Web Cluster Server

To solve the problem of inadequate resource utility in cluster Web server using existing differentiated services mechanisms, the MCDDS(differentiated services with multi-class bounded delay) mechanism for cluster Web server was proposed.The MCDDS mechanism makes the requests of users with lower priority can use the resource that are not used by requests of users with higher priority and improves the resource utility.The mathematical formula for real-time detecting parameters and bounded delay of each priority user's requests is built by combining the priority scheduling policy with queue theory,and the dynamical admission control and dispatching policy are implemented to control the request delay of each priority user.Simulation test shows that MCDDS is more efficient than existing mechanisms,and the system resource utility is increased by 61% under high workload and the request mean delay of each priority user can be controlled within bounded delay.