【摘要】 虚拟机技术作为云计算的重要技术之一,近年来得到广泛关注,但是由于虚拟机管理层的存在,导致语义鸿沟,使得实时应用程序、并发程序等在虚拟机上的运行性能受到影响。分析和研究了Xen虚拟机管理器的Credit调度算法,针对其在并发调度和软实时调度方面存在的不足,提出了改进调度算法,实现了算法的调度器原型。新的调度算法对软实时虚拟机进行Credit比例预分配,采用动态调度时间片机制,以non-work-conserving方式实现软实时任务周期调度,保障调度周期满足运行周期要求。通过区分并发和非并发软实时虚拟机,采取不同的调度策略,在满足资源利用率的基础上,确保实时任务的顺利运行。测试结果表明,该调度算法在对并发和非并发软实时任务调度上,具有良好的表现,较好满足了软实时应用调度需求。更多还原

【Abstract】 As one of the most important technology of cloud computing,virtual machine(VM)technology has attracted considerable attention in recent years.But the virtual machine monitor(VMM)impacts the performance of real-time applications and parallel applications due to semantic gap.In this paper we analyze the Credit scheduler of Xen VMM,propose a novel soft real-time scheduling algorithm based on the Credit,and implement a scheduler prototype base on the new algorithm,which can satisfy the requirements of the soft real-time VM scheduling.In this new scheduling algorithm the Credit is preallocated to the soft real-time VMs according to the occupation rate of the CPU,and the scheduler adopts the dynamic time slice scheduling mechanism and works in non-work-conserving mode to realize soft real-time scheduling so as to guarantee that the scheduling period meets the requirements.Distinguishing the parallel and the non-parallel VMs and using different strategies ensure the execution of realtime tasks as well as meet the requirement of resource utilization.Test results show that the new algorithm has good performance in scheduling both parallel and non-parallel soft real-time tasks and hence meets the requirements of soft real-time application scheduling.更多还原