The Study, Based On The Performance Of The Xen Network Virtualization

Advancement in computer hardware, as well as the diversity of user applications make virtualization technology to become a research focus again in the industry and academia. Using virtualization technology can improve the utilization of computer resources, and reduce overall system cost. Currently, virtualization technology has been widely applied to the server consolidation, cluster computing, dynamic resource migration, system security and system development and testing and so on.In recent years, more and more enterprises and schools joined to research virtualization technology, virtualization technology gets an unprecedented development, XEN is an excellent virtualization products. XEN is developed by the University of Cambridge,and it is an open source project, which allows a computer to run multiple guest operating system concurrently. At the beginning, XEN only supports paravirtualization technology, but since 2005, INTEL and AMD develop virtualization technology of processor-based hardware, and this makes XEN not only supports paravirtualization techonology but also supports full virtualization. The performance and resource isolation of XEN are very good, and it is an open source project, so XEN is studyed by more and more people in recent days. Based on the above considerations,This paper also choose XEN as a research object.However, compared to native Linux, the overhead of network I/O virtualization can still significantly affect the performance of network-intensive applications, and this becomes a major obstacle for the wide usage of XEN. In XEN, relative to native Linux, the network performance of the guest domain is lower than the driver domain,when receiving packets, the receive performance in the guest domain achieves only 30% of the throughput achievable under native Linux, when sending packets, the transmit performance achieves only 20% of the throught achievable under native linux. In addition, with the rapid development of the Internet, there is a growing requirment of network-intensive applications in virtual machine, so how to improve the performance of network-intensive applications has become an urgent problem in virtual machine environment.Based on this, First, this paper by reading a lot of relevant literature, finds that the main reasons of affecting the performance of network-intensive applications in guest domain include two aspects:XEN network virtualization architecture, and the XEN CPU scheduling algorithm; Second, by analyzing XEN network virtualization architecture, and XEN Credit Scheduling Algorithm, we identify their specific reasons that makes the performance of network-intensive applications lower in the guest domain than in the native Linux; Third, we analysis and compare the existing optimization for the performance of improving network-intensive applications, in particular, in order to reduce the delay caused by the scheduling algorithm, we modify the Credit scheduling algorithm to make it schedule network-intensive and other I/O-intensive domain earlier than other domain, and by the method, the performance of network-intensive applications is improved; Finally, we compare the Credit scheduling algorithm with modified algorithm, and prove that modified algorithm improve the perfomance of neiwork-intensive applications.