云计算系统性能依赖性建模与分析

loud computing is considered to be a new type of computing mode after parallel computing, distributed computing and grid computing. Virtualization technology is the basis of cloud computing, and it makes a large number of virtual machines to run concurrently and to share the resources in the resource pool. However, just because of the resource sharing, performances of some jobs deployed in the cloud computing change along with the variation of other jobs or resources, and this is called as "performance jitter". What's more, jobs deployed in the cloud computing (especially the computing intensive tasks and storage intensive tasks) are usually divided into several tasks, which are allocated to different virtual machines to be executed in a parallel mode. The division degree of the jobs (which refers to the number of tasks that a job is divided into) determines how close the sharing relationship between the jobs are, then determines the "performance jitter" degree of the jobs. In this paper, the "performance jitter" of the jobs are discussed in two scenarios, one is that a new job is inserted into the cloud computing, the other is that a shared physical resource is down. The simulation results show that the "performance jitter" of one job is not only related to the variation of other jobs or resources, but also closely related to average division degree of the jobs.