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The Single Root I/O Virtualization (SR-IOV) specification is a standard for a type of PCI device assignment that can share a single device with multiple pods.

SR-IOV can segment a compliant network device, recognized on the host node as a physical function (PF), into multiple virtual functions (VFs). The VF is used like any other network device. The SR-IOV network device driver for the device determines how the VF is exposed in the container:

  • netdevice driver: A regular kernel network device in the netns of the container

  • vfio-pci driver: A character device mounted in the container

You can use SR-IOV network devices with additional networks on your OpenShift Container Platform cluster installed on bare metal or Red Hat OpenStack Platform (RHOSP) infrastructure for applications that require high bandwidth or low latency.

You can enable SR-IOV on a node by using the following command:

$ oc label node <node_name> feature.node.kubernetes.io/network-sriov.capable="true"

Components that manage SR-IOV network devices

The SR-IOV Network Operator creates and manages the components of the SR-IOV stack. It performs the following functions:

  • Orchestrates discovery and management of SR-IOV network devices

  • Generates NetworkAttachmentDefinition custom resources for the SR-IOV Container Network Interface (CNI)

  • Creates and updates the configuration of the SR-IOV network device plugin

  • Creates node specific SriovNetworkNodeState custom resources

  • Updates the spec.interfaces field in each SriovNetworkNodeState custom resource

The Operator provisions the following components:

SR-IOV network configuration daemon

A daemon set that is deployed on worker nodes when the SR-IOV Network Operator starts. The daemon is responsible for discovering and initializing SR-IOV network devices in the cluster.

SR-IOV Network Operator webhook

A dynamic admission controller webhook that validates the Operator custom resource and sets appropriate default values for unset fields.

SR-IOV Network resources injector

A dynamic admission controller webhook that provides functionality for patching Kubernetes pod specifications with requests and limits for custom network resources such as SR-IOV VFs. The SR-IOV network resources injector adds the resource field to only the first container in a pod automatically.

SR-IOV network device plugin

A device plugin that discovers, advertises, and allocates SR-IOV network virtual function (VF) resources. Device plugins are used in Kubernetes to enable the use of limited resources, typically in physical devices. Device plugins give the Kubernetes scheduler awareness of resource availability, so that the scheduler can schedule pods on nodes with sufficient resources.

SR-IOV CNI plugin

A CNI plugin that attaches VF interfaces allocated from the SR-IOV network device plugin directly into a pod.

SR-IOV InfiniBand CNI plugin

A CNI plugin that attaches InfiniBand (IB) VF interfaces allocated from the SR-IOV network device plugin directly into a pod.

The SR-IOV Network resources injector and SR-IOV Network Operator webhook are enabled by default and can be disabled by editing the default SriovOperatorConfig CR.

Supported platforms

The SR-IOV Network Operator is supported on the following platforms:

  • Bare metal

  • Red Hat OpenStack Platform (RHOSP)

Supported devices

OpenShift Container Platform supports the following network interface controllers:

Table 1. Supported network interface controllers
Manufacturer Model Vendor ID Device ID

Broadcom

BCM57414

14e4

16d7

Broadcom

BCM57508

14e4

1750

Intel

X710

8086

1572

Intel

XL710

8086

1583

Intel

XXV710

8086

158b

Intel

E810-CQDA2

8086

1592

Intel

E810-2CQDA2

8086

1592

Intel

E810-XXVDA2

8086

159b

Intel

E810-XXVDA4

8086

1593

Mellanox

MT27700 Family [ConnectX‑4]

15b3

1013

Mellanox

MT27710 Family [ConnectX‑4 Lx]

15b3

1015

Mellanox

MT27800 Family [ConnectX‑5]

15b3

1017

Mellanox

MT28880 Family [ConnectX‑5 Ex]

15b3

1019

Mellanox

MT28908 Family [ConnectX‑6]

15b3

101b

Mellanox

MT2892 Family [ConnectX‑6 Dx]

15b3

101d

Mellanox

MT2894 Family [ConnectX‑6 Lx]

15b3

101f

Pensando [1]

DSC-25 dual-port 25G distributed services card for ionic driver

0x1dd8

0x1002

Pensando [1]

DSC-100 dual-port 100G distributed services card for ionic driver

0x1dd8

0x1003

  1. OpenShift SR-IOV is supported, but you must set a static, Virtual Function (VF) media access control (MAC) address using the SR-IOV CNI config file when using SR-IOV.

For the most up-to-date list of supported cards and compatible OpenShift Container Platform versions available, see Openshift Single Root I/O Virtualization (SR-IOV) and PTP hardware networks Support Matrix.

Automated discovery of SR-IOV network devices

The SR-IOV Network Operator searches your cluster for SR-IOV capable network devices on worker nodes. The Operator creates and updates a SriovNetworkNodeState custom resource (CR) for each worker node that provides a compatible SR-IOV network device.

The CR is assigned the same name as the worker node. The status.interfaces list provides information about the network devices on a node.

Do not modify a SriovNetworkNodeState object. The Operator creates and manages these resources automatically.

Example SriovNetworkNodeState object

The following YAML is an example of a SriovNetworkNodeState object created by the SR-IOV Network Operator:

An SriovNetworkNodeState object
apiVersion: sriovnetwork.openshift.io/v1
kind: SriovNetworkNodeState
metadata:
  name: node-25 (1)
  namespace: openshift-sriov-network-operator
  ownerReferences:
  - apiVersion: sriovnetwork.openshift.io/v1
    blockOwnerDeletion: true
    controller: true
    kind: SriovNetworkNodePolicy
    name: default
spec:
  dpConfigVersion: "39824"
status:
  interfaces: (2)
  - deviceID: "1017"
    driver: mlx5_core
    mtu: 1500
    name: ens785f0
    pciAddress: "0000:18:00.0"
    totalvfs: 8
    vendor: 15b3
  - deviceID: "1017"
    driver: mlx5_core
    mtu: 1500
    name: ens785f1
    pciAddress: "0000:18:00.1"
    totalvfs: 8
    vendor: 15b3
  - deviceID: 158b
    driver: i40e
    mtu: 1500
    name: ens817f0
    pciAddress: 0000:81:00.0
    totalvfs: 64
    vendor: "8086"
  - deviceID: 158b
    driver: i40e
    mtu: 1500
    name: ens817f1
    pciAddress: 0000:81:00.1
    totalvfs: 64
    vendor: "8086"
  - deviceID: 158b
    driver: i40e
    mtu: 1500
    name: ens803f0
    pciAddress: 0000:86:00.0
    totalvfs: 64
    vendor: "8086"
  syncStatus: Succeeded
1 The value of the name field is the same as the name of the worker node.
2 The interfaces stanza includes a list of all of the SR-IOV devices discovered by the Operator on the worker node.

Example use of a virtual function in a pod

You can run a remote direct memory access (RDMA) or a Data Plane Development Kit (DPDK) application in a pod with SR-IOV VF attached.

This example shows a pod using a virtual function (VF) in RDMA mode:

Pod spec that uses RDMA mode
apiVersion: v1
kind: Pod
metadata:
  name: rdma-app
  annotations:
    k8s.v1.cni.cncf.io/networks: sriov-rdma-mlnx
spec:
  containers:
  - name: testpmd
    image: <RDMA_image>
    imagePullPolicy: IfNotPresent
    securityContext:
      runAsUser: 0
      capabilities:
        add: ["IPC_LOCK","SYS_RESOURCE","NET_RAW"]
    command: ["sleep", "infinity"]

The following example shows a pod with a VF in DPDK mode:

Pod spec that uses DPDK mode
apiVersion: v1
kind: Pod
metadata:
  name: dpdk-app
  annotations:
    k8s.v1.cni.cncf.io/networks: sriov-dpdk-net
spec:
  containers:
  - name: testpmd
    image: <DPDK_image>
    securityContext:
      runAsUser: 0
      capabilities:
        add: ["IPC_LOCK","SYS_RESOURCE","NET_RAW"]
    volumeMounts:
    - mountPath: /dev/hugepages
      name: hugepage
    resources:
      limits:
        memory: "1Gi"
        cpu: "2"