Abstract: In order to decrease the I/O response time of Virtual CPU(VCPU) with I/O task and CPU intensive task in the default Credit scheduling algorithm of Xen Virtual Machine Manager(VMM),this paper presents a dynamic time slice self-adaptive algorithm based on Credit,named SACredit.It assesses the number of virtual machines of VCPU queue and I/O events by monitoring system response of VCPU queue and I/O event.BOOST mechanism is used in the algorithm,where VCPU can be waked up by I/O event at any time.The I/O response time can be reduced obviously,and with the way of dynamic time slice self-adaption,the fairness and balancing of credit scheduler can be reserved.Experimental result shows that SACredit has low I/O response delay,and retains the advantages of Credit scheduling algorithm in the aspects of resources proportional fair distribution and load balancing.

Key words: Credit scheduling algorithm, I/O response delay, BOOST priority, dynamic time slice, self-adaptive scheduling

摘要： 针对Xen虚拟机管理器默认的Credit调度算法中,同时运行I/O任务和CPU密集任务的虚拟CPU(VCPU)存在I/O响应延迟问题,提出动态时间片自适应调度算法SACredit。通过监测系统中VCPU队列和I/O事件的响应情况,评估混合I/O任务及CPU密集型任务对虚拟机数量的影响,结合BOOST优先级机制,实现调度时间片的自适应调整,从而降低系统中虚拟机I/O响应延迟,并通过控制调度时间片,保证各虚拟机在调度过程中的公平性。实验结果表明,SACredit对于系统I/O响应性能的优化效果明显,并且保留了Credit调度算法资源按比例公平分配和多CPU负载均衡的特点。

关键词: Credit调度算法, I/O响应延迟, BOOST优先级, 动态时间片, 自适应调度

CLC Number: 

• TP391