4. AVP Poll Mode Driver

The Accelerated Virtual Port (AVP) device is a shared memory based device only available on virtualization platforms from Wind River Systems. The Wind River Systems virtualization platform currently uses QEMU/KVM as its hypervisor and as such provides support for all of the QEMU supported virtual and/or emulated devices (e.g., virtio, e1000, etc.). The platform offers the virtio device type as the default device when launching a virtual machine or creating a virtual machine port. The AVP device is a specialized device available to customers that require increased throughput and decreased latency to meet the demands of their performance focused applications.

The AVP driver binds to any AVP PCI devices that have been exported by the Wind River Systems QEMU/KVM hypervisor. As a user of the DPDK driver API it supports a subset of the full Ethernet device API to enable the application to use the standard device configuration functions and packet receive/transmit functions.

These devices enable optimized packet throughput by bypassing QEMU and delivering packets directly to the virtual switch via a shared memory mechanism. This provides DPDK applications running in virtual machines with significantly improved throughput and latency over other device types.

The AVP device implementation is integrated with the QEMU/KVM live-migration mechanism to allow applications to seamlessly migrate from one hypervisor node to another with minimal packet loss.

4.1. Features and Limitations of the AVP PMD

The AVP PMD driver provides the following functionality.

  • Receive and transmit of both simple and chained mbuf packets,
  • Chained mbufs may include up to 5 chained segments,
  • Up to 8 receive and transmit queues per device,
  • Only a single MAC address is supported,
  • The MAC address cannot be modified,
  • The maximum receive packet length is 9238 bytes,
  • VLAN header stripping and inserting,
  • Promiscuous mode
  • VM live-migration
  • PCI hotplug insertion and removal

4.2. Prerequisites

The following prerequisites apply:

  • A virtual machine running in a Wind River Systems virtualization environment and configured with at least one neutron port defined with a vif-model set to “avp”.

4.3. Launching a VM with an AVP type network attachment

The following example will launch a VM with three network attachments. The first attachment will have a default vif-model of “virtio”. The next two network attachments will have a vif-model of “avp” and may be used with a DPDK application which is built to include the AVP PMD driver.

nova boot --flavor small --image my-image \
   --nic net-id=${NETWORK1_UUID} \
   --nic net-id=${NETWORK2_UUID},vif-model=avp \
   --nic net-id=${NETWORK3_UUID},vif-model=avp \
   --security-group default my-instance1