Virtualization technology essentially componentizes a computer system into the following:
PCI Express with Single Root I/O Virtualization (SR-IOV) enables some of the virtualization to be done in hardware for the I/O devices instead of software, thereby streamlining the Virtualization Intermediary. Of course, hardware runs faster than software for the same function, so PCI Express with SR-IOV helps improve the overall system performance of a virtualized system.
To understand the benefits of PCI Express with SR-IOV, you can watch SolarFlare’s demo that was videotaped in the Synopsys booth at the Intel Developer’s Forum (IDF) conference in 2011 (shown below). The demo utilizes two servers running Citrix XenServer 6 to showcase the 3x in performance achieved when utilizing PCI Express 2.0 with SR-IOV virtualization technology. By incorporating DesignWare PCIe IP with SR-IOV, SolarFlare’s Dual Port SFP+ 10GbE Server Adapters were able to support hundreds of virtual PCIe functions and thousands of virtual NICs, thus reducing total hardware costs and power consumption, while increasing performance.
It’s tough to explain such complex technology in a blog posting, but in a nutshell, PCI Express with SR-IOV enables virtualization of a single physical I/O device to masquerade as multiple virtualized I/O devices, one for each virtual machine and with complete independence from each other. You can learn more about how virtualization benefits PCI Express by reading this whitepaper: