| Virtualization technology is an important technology in computer's architecture. With the increasing performance of personal computer hardware, Virtualization technology's in computer field range of application is wider and wider. So Virtualization technology may become a future trend in computer development.In Virtualization technology, virtualization physical resource can be classified into three main tasks:CPU virtualization, memory virtualization and I/O virtualization. Therefore, I/O virtualization is no doubt an important part in virtualization technology. However, on traditional X86 system use software to simulate a device or use a par-virtualization way to implement virtualization, in their implementation and their performance both have their inherent characteristic. The method using software to simulate device is versatile, but it is difficult to implementation, and the performance is not ideal. Using Para-virtualization approach, the performance has been greatly improved, but lack of versatility. So based on Intel's virtualization technology for directed I/O (VT-d), we implement the I/O virtualization. In this way, we can not only have good performance but also it is versatile. The technology using hardware support for DMA remapping, setting of I/O pages, interrupt remapping make it is possible that any virtual machine can direct using its hardware device. In this way, we achieve the improvement in performance.This paper first reviews the modern virtualization technology and analyses the defect in I/O virtualization in full virtualization. Then describe using software to emulate IDE disk and using VT-d to implement the architecture on I/O virtualization based on SmartVMM which is developed by our lab, illustrate details in each module. At last on the SmartVMM platform, we use software to emulate IDE disk and VT-d technology to implement the virtual machine using DMA to access to IDE disk device; and evaluate the performance of the two methods on the SmartVMM system. |
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