The Research Of Inter-domain Communication Optimization Under Xen Hardware-assisted Virtualization

Virtualization technology originates from the IBM mainframe, the development ofInternet and IT industry brings different virtualization technologies, such as servervirtualization, network virtualization, microprocessor virtualization, file system virtualization,and storage virtualization technologie. In recent years, with the development of the Internet,virtual machine technology is used more and more in the server consolidation, securitysystems of distributed and other areas. However, the virtual machine features that make theindependence and isolated virtual machines on the same physical machine results thecommunication and data transfer between the performances greatly reduced. Existing virtualmachine technology, communication is completed through the standard inter-domain virtualnetwork I/O, the transmission of network packets from the sender needs to send to the virtualnetwork card in Dom0network device simulation module, and then from the Dom0sent tothe receiver the virtual card. In this packet transmission process to go through multipledomains processing, and also conducted a number of CPU privilege level switch andoperation mode switching; this is the main reasons for subject to inter-domain communicationperformance loss. Therefore, this domain for Xen virtual machine communication betweenthe hardware problems of low performance proposed a inter-domain traffic optimizationmodel, communicating directly between the data transmission channel for data transmissionby sharing memory hardware in the two virtual machines.First，This paper introduces the background and current research of virtual machinetechnology, summarizes the necessary key technologies and mechanisms of Xen, analyzes thedetail of the Xen network hardware I/O virtualization model and working process of theinter-domain communication, and sums up the reasons of inter-domain communicationperformance loss.Then, this paper combines the reason of inter-domain communication performance lossbetween hardware virtual machines with the characteristics of its hardware virtualization,proposed data transfer optimization model based on shared memory. Optimization model hasthe following advantage: data transmission is not through the virtual network I/O, but by wayof inter-domain bi-directional shared memory data transfer, improved data transmissionreliability and efficiency; reduced the overhead through the mechanism of inter-domain eventchannel provides for data transmission Management and control services; in the hardwarevirtual machine provided filtering function of data packets from the protocol stack between the shared memory buffer to the domain forwarding by NDIS intermediate driver forwards thepacket; Xenstore unified management through participation in inter-domain communicationVirtual machine hardware information to achieve data transmission channel between thedomain of automatic mechanisms.Finally, the experiment tests the network transmission bandwidth, delay, domain switchoverhead and CPU Utilization， proves that the optimization model has more betterperformance than the original model.