With PoC FDP-1286 we evaluate userspace datapaths with OVS-DPDK for OpenShift's default CNI plugin OVN-Kubernetes, OpenShift's default CNI plugin. In the previous PoC FDP-1285 we moved container networking to userspace by replacing veth devices with VDUSE devices. Now, we also want to move networking of KubeVirt virtual machines to userspace with help of the vhost-vdpa protocol.

We explored available options for attaching KubeVirt virtual machines to networks and agreed on an architecture for VDUSE/vhost-vDPA support in our KubeVirt PoC FDP-1286 (FDP-1309, summary from 2025-07-01):

• We developed a new Kubernetes device plugin that creates VDUSE/vhost-vDPA ports in OVS and their associated vhost-vDPA character devices (FDP-1513).
• We evaluated and extended OVN-Kubernetes as our CNI for exposing vhost-vDPA char devices from OVS VDUSE ports to pods (FDP-1514).
• We developed a new CNI with the minimum required functionality to expose the vhost-vDPA character device, provided by the new device plugin (FDP-1513), to a pod. It will serve as a reference implementation for customers such as Orange (FDP-1516).
• We implemented support for attaching VMs to userspace networks using the vhost-vdpa protocol in KubeVirt (FDP-1515).

This ultimately moved the entire OpenShift networking stack to userspace.

We now aim to evaluate the performance and latency of our userspace networking stack. Franck Baudin requested results for VM-to-VM traffic across bare-metal nodes: We will deploy a multi-node OpenShift (MNO) cluster on bare-metal servers, launch two VMs on separate nodes, and run benchmarks between them. We will engage QE engineers from our vDPA group to help define and run meaningful benchmarks.

We replicate this setup for both CNIs: OVN-Kubernetes CNI (FDP-1514) and the new CNI (FDP-1516). This setup will enable us to compare stock OpenShift with OVN-Kubernetes against a cluster running the vhost-vDPA-enabled OVN-Kubernetes CNI, as well as to compare the vhost-vDPA-enabled OVN-Kubernetes CNI with Maxime's new CNI.

This task covers benchmarking on QE's bare-metal servers, while FDP-1546 covers benchmarking on our servers.