Abstract: This paper presents three real-time scheduling schemes for cluster servers：centralized scheme，distributed scheme and pull-based distributed scheme.Distributed scheme deploys scheduling on the end-node，while the scheduling work of centralized scheme is on the front-nodes，and that makes the former has a greater scalability.Pull-based distributed scheme makes end-nodes ask for events and direct load balance by themselves，to improve the scalability and efficiency of real-time cluster system.Lots of experimental results have been presented，illustrating the three scheduling schemes are benefit for decreasing the response time and maximizing the system throughout.

Key words: cluster server, real-time service, scheduling schemes, real-time response characteristic

摘要： 研究了集群架构服务器的三种实时调度策略，即集中式策略、分布式策略和主动型全分布策略。与调度功能主要集中在前端机的集中式策略比较，分布式策略将调度功能部分离散至后端节点，改善了系统的可扩展性。而主动型全分布式调度则进一步实现了调度分派功能的完全离散化，通过后端机的主动拉取事件和频率调控实现了负载平衡的自调节，极大地改善了系统的扩展性和服务效率。通过试验研究和试验表明，这三种都有效地降低了集群的响应服务请求的时间，还保证了系统的输出最大化。

关键词: 集群服务器, 实时服务, 调度策略, 实时响应特性