Research On Split I/O Virtualization Technology

Cross-platform virtualization is an important means to resolve the operating system and application transparent migration issues, it is important to promote the popularization of new processors. I/O virtualization is one of the cross-platform virtualization main contents, which is aiming at simulating the ways of working and I/O resources of source platform on the target platform, and providing environmental support for the source platform software transparently running on the target platform. It has important research value.Firstly, this paper describes the main way to achieve I / O virtualization technology, and focuses on analyzing the advantages of performance and need of hardware support for direct distribution model. Based on cross-platform system virtual machine monitor ARCH-BRIDGE, this paper analyses the current I/O virtualization technology problems and then combined with the advantages of different virtualization technology this paper presents a split I/O virtualization framework for cross-platform system virtualization, which can separate I/O virtualization subsystem from virtual machine monitor in order to achieve I/O device virtualization and virtual machine monitor running in parallel virtual machine monitor, direct access to the host hardware resources to accelerate I/O access, which can enhance cross-platform virtualization performance. This paper designs the I/O virtualization mechanism based on multi-tasking and implements split VIO process in the framework, which uses the way of asynchronous I/O to solve performance loss problems of virtual processor emulation involved of device simulation in cross-platform I/O virtualization. In addition, this paper presents a technique of device directly assigned in cross-platform system virtualization environment. This technique achieves device discovery, I/O address translation, memory address translation interrupt remapping and other core functions related to device directly assigned in cross-platform. With the use of this technique, the driver in virtual machine can directly access hardware devices on the host platform, and effectively shorten the I/O path to the virtual machine operations.The tests show that with the use of split I/O virtualization technology, disk read performance increases about 8.59% and disk write performance increases about 7.73% in single-threaded file read and write tests. In multi-threaded file read and write performance tests the increase of performance is more than 20%, VGA processing performance is more than 9.2% improvement in different scenario tests. In the use of cross-platform I / O direct assignment technology, disk read and write speed increase is above 30%.