There are several approaches to I/O virtualization(IOV). One uses InfiniBand another, Single Root I/O Virtualization( SR-IOV), is an extension ofPCI Express( PCIe). SR-IOV virtualization allows a PCIe device to be virtualized as if it were many separate PCIe devices.
SR-IOV technology is also used in network interface cards( NIC) of 10 Gigabit Ethernet and can represent I/O channels to a virtual machine as if they were multiple NICs in virtualized environments. SR-IOV is intended to eliminate I/O bottlenecks in virtualized server environments. Data rates of 30 Gbit/s can be realized with the method.
The specifications for SR-IOV were developed by the PCI Special Interest Group (PCI- SIG) and are intended to support interoperability between different systems and are based on the Physical Functions( PF) and the Virtual Functions( VF). The physical functions are the PCIe functions with all management functions for the PCIe devices. The virtual functions are simple PCIe functions without configuration functions. The virtual functions support the I/O functions. The VF functions can also not be configured because this would change the underlying physical functions and the other virtual functions.