Kubernetes优秀的架构设计，借助multus cni intel userspace cni 可以屏蔽了DPDK底层的复杂，让KubeVirt 支持DPDK变得比较容易。
因为 e2e验证 等原因，KubeVirt社区至今未加入对DPDK支持，本篇试着在最新版的KubeVirt v0.53加入DPDK功能。
network Phase1 & Phase2
Phase1 | Phase2 | |
|---|---|---|
权限 | 大（privileged networking configuration） | 小（unprivileged networking configuration） |
发生场所 | the virt-handler process | virt-launcher process |
主要功能 | 第一步是决定改使用哪种 BindMechanism，一旦 BindMechanism 确定，则依次调用以下方法：1. discoverPodNetworkInterface：获取 Pod 网卡设备相关的信息，包括 IP 地址，路由，网关等信息2. preparePodNetworkInterfaces：基于前面获取的信息，配置网络3. setCachedInterface：缓存接口信息在内存中4. setCachedVIF：在文件系统中持久化 VIF 对象 | 和Phase1一样Phase2 也会选择正确的 BindMechanism，然后取得 Phase1 的配置信息（by loading cached VIF object）。基于 VIF 信息， proceed to decorate the domain xml configuration of the VM it will encapsulate |
DPDK不需要Phase1做任何事情，因为不需要获取Pod的网络信息，也不需要缓存Pod的网络和配置vm的网络。
Phase2是基于Phase1的后续，所以DPDK也不需要Phase2做任何事情。
代码语言：javascript复制func (l *podNIC) PlugPhase1() error {
...
if l.vmiSpecIface.Vhostuser != nil {
return nil
}
...language-go复制代码func (l *podNIC) PlugPhase2(domain *api.Domain) error {
...
if l.vmiSpecIface.Vhostuser != nil {
return nil
}
...language-go复制代码准备Pod with DPDK mainifest
pkg/virt-controller/services/template.go
代码语言：javascript复制const VhostuserSocketDir = "/var/lib/cni/usrcni/"const OvsRunDirDefault = "/var/run/openvswitch/"const PodNetInfoDefault = "/etc/podnetinfo"func addVhostuserVolumes(volumeMounts *[]k8sv1.VolumeMount, volumes *[]k8sv1.Volume) {
// "shared-dir" volume name will be used by userspace cni to place the vhostuser socket file`
*volumeMounts = append(*volumeMounts, k8sv1.VolumeMount{
Name: "shared-dir",
MountPath: VhostuserSocketDir,
})
*volumes = append(*volumes, k8sv1.Volume{
Name: "shared-dir",
VolumeSource: k8sv1.VolumeSource{
EmptyDir: &k8sv1.EmptyDirVolumeSource{
Medium: k8sv1.StorageMediumDefault,
},
},
})
// Libvirt uses ovs-vsctl commands to get interface stats
*volumeMounts = append(*volumeMounts, k8sv1.VolumeMount{
Name: "ovs-run-dir",
MountPath: OvsRunDirDefault,
})
*volumes = append(*volumes, k8sv1.Volume{
Name: "ovs-run-dir",
VolumeSource: k8sv1.VolumeSource{
HostPath: &k8sv1.HostPathVolumeSource{
Path: OvsRunDirDefault,
},
},
})}func addPodInfoVolumes(volumeMounts *[]k8sv1.VolumeMount, volumes *[]k8sv1.Volume) {
// userspace cni will set the vhostuser socket details in annotations, app-netutil helper
// will parse annotations from /etc/podnetinfo to get the interface details of
// vhostuser socket (which will be added to VM xml)
*volumeMounts = append(*volumeMounts, k8sv1.VolumeMount{
Name: "podinfo",
// TODO: (skramaja): app-netutil expects path to be /etc/podnetinfo, make it customizable
MountPath: PodNetInfoDefault,
})
*volumes = append(*volumes, k8sv1.Volume{
Name: "podinfo",
VolumeSource: k8sv1.VolumeSource{
DownwardAPI: &k8sv1.DownwardAPIVolumeSource{
Items: []k8sv1.DownwardAPIVolumeFile{
{
Path: "labels",
FieldRef: &k8sv1.ObjectFieldSelector{
APIVersion: "v1",
FieldPath: "metadata.labels",
},
},
{
Path: "annotations",
FieldRef: &k8sv1.ObjectFieldSelector{
APIVersion: "v1",
FieldPath: "metadata.annotations",
},
},
},
},
},
})}func (t *templateService) renderLaunchManifest(vmi *v1.VirtualMachineInstance, imageIDs map[string]string, tempPod bool) (*k8sv1.Pod, error) {
...
if util.IsVhostuserVmi(vmi) {
...
addVhostuserVolumes(&volumeMounts, &volumes)
addPodInfoVolumes(&volumeMounts, &volumes)
...
}
...language-go复制代码代码语言：javascript复制生成类似下面的pod yaml
volumes:
- name: vhostuser-sockets
emptyDir: {}containers:
- name: vm
image: vm-vhostuser:latest
volumeMounts:
- name: vhostuser-sockets
mountPath: /var/run/vmlanguage-yaml复制代码准备libvirt xml define
pkg/virt-launcher/virtwrap/converter/network.go
代码语言：javascript复制...} else if iface.Vhostuser != nil {
networks := map[string]*v1.Network{}
cniNetworks := map[string]int{}
multusNetworkIndex := 1
for _, network := range vmi.Spec.Networks {
numberOfSources := 0
if network.Pod != nil {
numberOfSources
}
if network.Multus != nil {
if network.Multus.Default {
// default network is eth0
cniNetworks[network.Name] = 0
} else {
cniNetworks[network.Name] = multusNetworkIndex
multusNetworkIndex
}
numberOfSources
}
if numberOfSources == 0 {
return nil, fmt.Errorf("fail network %s must have a network type", network.Name)
} else if numberOfSources > 1 {
return nil, fmt.Errorf("fail network %s must have only one network type", network.Name)
}
networks[network.Name] = network.DeepCopy()
}
domainIface.Type = "vhostuser"
interfaceName := GetPodInterfaceName(networks, cniNetworks, iface.Name)
vhostPath, vhostMode, err := getVhostuserInfo(interfaceName, c)
if err != nil {
log.Log.Errorf("Failed to get vhostuser interface info: %v", err)
return nil, err }
vhostPathParts := strings.Split(vhostPath, "/")
vhostDevice := vhostPathParts[len(vhostPathParts)-1]
domainIface.Source = api.InterfaceSource{
Type: "unix",
Path: vhostPath,
Mode: vhostMode,
}
domainIface.Target = &api.InterfaceTarget{
Device: vhostDevice,
}
//var vhostuserQueueSize uint32 = 1024
domainIface.Driver = &api.InterfaceDriver{
//RxQueueSize: &vhostuserQueueSize,
//TxQueueSize: &vhostuserQueueSize,
}}language-go复制代码func getVhostuserInfo(ifaceName string, c *ConverterContext) (string, string, error) {
if c.PodNetInterfaces == nil {
err := fmt.Errorf("PodNetInterfaces cannot be nil for vhostuser interface")
return "", "", err }
for _, iface := range c.PodNetInterfaces.Interface {
if iface.DeviceType == "vhost" && iface.NetworkStatus.Interface == ifaceName {
return iface.NetworkStatus.DeviceInfo.VhostUser.Path, iface.NetworkStatus.DeviceInfo.VhostUser.Mode, nil
}
}
err := fmt.Errorf("Unable to get vhostuser interface info for %s", ifaceName)
return "", "", err}func GetPodInterfaceName(networks map[string]*v1.Network, cniNetworks map[string]int, ifaceName string) string {
if networks[ifaceName].Multus != nil && !networks[ifaceName].Multus.Default {
// multus pod interfaces named netX
return fmt.Sprintf("net%d", cniNetworks[ifaceName])
} else {
return PodInterfaceNameDefault }}language-go复制代码代码语言：javascript复制生成类似下面的libvrit xml define
<interface type='vhostuser'>
<mac address='00:00:00:0A:30:89'/>
<source type='unix' path='/var/run/vm/sock' mode='server'/>
<model type='virtio'/>
<driver queues='2'>
<host mrg_rxbuf='off'/>
</driver></interface>language-markup复制代码变更KubeVirt API
staging/src/kubevirt.io/api/core/v1/schema.go
代码语言：javascript复制type InterfaceBindingMethod struct {
Bridge *InterfaceBridge `json:"bridge,omitempty"`
Slirp *InterfaceSlirp `json:"slirp,omitempty"`
Masquerade *InterfaceMasquerade `json:"masquerade,omitempty"`
SRIOV *InterfaceSRIOV `json:"sriov,omitempty"`
Vhostuser *InterfaceVhostuser `json:"vhostuser,omitempty"`
Macvtap *InterfaceMacvtap `json:"macvtap,omitempty"`}language-go复制代码type InterfaceVhostuser struct{}language-go复制代码代码语言：javascript复制支持类似下面的CRD
apiVersion: kubevirt.io/v1kind: VirtualMachineInstancemetadata:
name: vm-trex-1spec:
domain:
devices:
interfaces:
- name: default
masquerade: {}
- name: vhost-user-net-1
vhostuser: {}
networks:
- name: default
pod: {}
- name: vhost-user-net-1
multus:
networkName: userspace-ovs-net-1language-yaml复制代码感觉KubeVirt增加DPDK不是很复杂，只是在KubeVirt自动化流程上多加点DPDK相关的pod yaml部分，vm define xml部分。关键是对DPDK功能的验证，今后再开一篇补上验证相关的内容。
附：DPDK vHost User Ports
Open vSwitch 提供两种类型的 vHost User ports:
- vhost-user (dpdkvhostuser)
- vhost-user-client (dpdkvhostuserclient)
vHost User采用客户端服务端模式。服务端 creates/manages/destroys the vHost User sockets。客户端连接到服务端。
For vhost-user ports, Open vSwitch acts as the server and QEMU the client.
代码语言：javascript复制ovs-vsctl add-port br0 vhost-user-1 -- set Interface vhost-user-1 type=dpdkvhostuser复制代码libvirt xml define
代码语言：javascript复制<interface type='vhostuser'>
<mac address='00:00:00:00:00:01'/>
<source type='unix' path='/usr/local/var/run/openvswitch/dpdkvhostuser0' mode='client'/>
<model type='virtio'/>
<driver queues='2'>
<host mrg_rxbuf='off'/>
</driver>
</interface>复制代码For vhost-user-client ports, Open vSwitch acts as the client and QEMU the server.
代码语言：javascript复制VHOST_USER_SOCKET_PATH=/path/to/socket
ovs-vsctl add-port br0 vhost-client-1 -- set Interface vhost-client-1 type=dpdkvhostuserclient options:vhost-server-path=$VHOST_USER_SOCKET_PATH复制代码libvirt xml define
代码语言：javascript复制 <interface type='vhostuser'>
<mac address='00:00:00:0A:30:89'/>
<source type='unix' path='/var/run/vm/sock' mode='server'/>
<model type='virtio'/>
<driver queues='2'>
<host mrg_rxbuf='off'/>
</driver>
</interface>复制代码由于在QEMU中不支持动态重新连接中，因此在OVS-DPDK中已弃用了dpdkvhostuser模式。dpdkvhostuser模式重新启动OVS需要重新启动VM。 在 DPDK vhostuserclient 模式下，QEMU充当服务器，QEMU创建了Vhostuser套接字文件，此时OVS充当客户端。即使重新启动OVS也不会影响VM，因为OVS可以在重新启动后连接到socket，OVS支持重启后自动重新连接。 由于旧模式 DPDK VHostuser 被弃用，KubeVirt仅实现了DPDK VHostUserClient模式。 OVS-DPDK 借助vhostuser socket绕过内核空间，增强了应用程序的数据包处理性能，它需要启用大页内存，在host和guest间共享数据包处理。 userspace CNI 借助 multus CNI增加一个额外的DPDK网络，在 OVS-DPDK 和 kubevirt (Qemu) 间共享 vhostuser socket。
