SR-IOV

SR-IOV technology is a hardware-based virtualization solution that can significantly improve both performance and scalability.

The SR-IOV standard facilitates efficient sharing of PCIe (Peripheral Component Interconnect Express) devices among virtual machines. This technology is implemented in hardware, which allows for I/O performance that rivals native, non-virtualized environments. The SR-IOV specification outlines a new standard that enables newly created devices to connect virtual machines directly to I/O devices (the SR-IOV specification is defined and maintained by the PCI-SIG at http://www.pcisig.com). A single I/O resource can be shared by numerous virtual machines. The shared device provides dedicated resources, as well as utilizes shared common resources. As a result, each virtual machine has access to unique resources. Therefore, PCIe devices (like Ethernet ports) with SR-IOV enabled and the right hardware and OS support can appear as multiple separate physical devices, each with their own PCIe configuration space.

SR-IOV is primarily used in virtualization but can also be applied to containers.

SR-IOV Configuration

modprobe ixgbevf
lspci -Dvmm|grep -B 1 -A 4 Ethernet
echo 2 > /sys/bus/pci/devices/0000:82:00.0/sriov_numvfs
# check ifconfig -a. You should see a number of new interfaces created, starting with “eth”, e.g. eth4

Docker SR-IOV Network Plugin

Intel has developed an SR-IOV network plugin for Docker, with the source code hosted at https://github.com/clearcontainers/sriov. It supports both runc and clearcontainer.

CNI Plugin

Intel maintains an SR-IOV CNI plugin, which is a fork from hustcat/sriov-cni, and extends support for DPDK.

The project homepage can be found at https://github.com/Intel-Corp/sriov-cni.

Advantages

• Excellent performance

• Does not consume computing resources

Disadvantages

• Limited number of VFs (Virtual Functions)

• Hardware binding does not support container migration

Reference Documents

• http://blog.scottlowe.org/2009/12/02/what-is-sr-iov/
• https://github.com/clearcontainers/sriov
• https://software.intel.com/en-us/articles/single-root-inputoutput-virtualization-sr-iov-with-linux-containers
• http://jason.digitalinertia.net/exposing-docker-containers-with-sr-iov/