Merge "OVS-DPDK integration documentation changed"

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Jenkins 2017-05-26 13:55:30 +00:00 committed by Gerrit Code Review
commit 0851546fd9
1 changed files with 79 additions and 8 deletions

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@ -30,7 +30,9 @@ Using DPDK in OVS requires the following minimum software versions:
* QEMU 2.1.0
* libvirt 1.2.13
Multiqueue support is available if the following newer versions are used:
Support of ``vhost-user`` multiqueue that enables use of multiqueue with
``virtio-net`` and ``igb_uio`` is available if the following newer
versions are used:
* OVS 2.5
* DPDK 2.2
@ -39,15 +41,44 @@ Multiqueue support is available if the following newer versions are used:
In both cases, install and configure Open vSwitch with DPDK support for each
node. For more information, see the
`OVS-DPDK <https://github.com/openvswitch/ovs/blob/v2.5.0/INSTALL.DPDK.md>`__
installation guide.
`OVS-DPDK <https://github.com/openvswitch/ovs/blob/master/Documentation/intro/install/dpdk.rst>`__
installation guide (select an appropriate OVS version in the
:guilabel:`Branch` drop-down menu).
`Neutron configuration reference for OVS-DPDK
<https://docs.openstack.org/developer/neutron/devref/ovs_vhostuser.html>`__
for configuration of neutron OVS agent.
In case you wish to configure multiqueue, see the
`OVS configuration chapter on vhost-user
<http://wiki.qemu.org/Documentation/vhost-user-ovs-dpdk#Enabling_multi-queue>`__
in QEMU documentation.
The technical background of multiqueue is explained in the corresponding
`blueprint <https://specs.openstack.org/openstack/nova-specs/specs/liberty/implemented/libvirt-virtiomq.html>`__.
Additionally, OpenStack supports ``vhost-user`` reconnect feature starting
from the Ocata release, as implementation of fix for
`bug 1604924 <https://bugs.launchpad.net/neutron/+bug/1604924>`__.
Starting from OpenStack Ocata release this feature is used without any
configuration necessary in case the following minimum software versions
are used:
* OVS 2.6
* DPDK 16.07
* QEMU 2.7
The support of this feature is not yet present in ML2 OVN and ODL
mechanism drivers.
Using vhost-user interfaces
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Once OVS is correctly configured with DPDK support, ``vhost-user`` interfaces
are completely transparent to the guest. However, guests must request large
pages. This can be done through flavors. For example:
Once OVS and neutron are correctly configured with DPDK support,
``vhost-user`` interfaces are completely transparent to the guest
(except in case of multiqueue configuration described below).
However, guests must request huge pages. This can be done through flavors.
For example:
.. code-block:: console
@ -72,13 +103,53 @@ fashion as conventional interfaces. These interfaces can use the kernel
$ openstack server create --nic net-id=$net_id ... testserver
Using vhost-user multiqueue
~~~~~~~~~~~~~~~~~~~~~~~~~~~
To use this feature, the following should be set in the flavor extra specs
(flavor keys):
.. code-block:: console
$ openstack flavor set $m1.large --property hw:vif_multiqueue_enabled=true
This setting can be overridden by the image metadata property if the feature
is enabled in the extra specs:
.. code-block:: console
$ openstack image set --property hw_vif_mutliqueue_enabled=true IMAGE_NAME
Support of ``virtio-net`` multiqueue needs to be present in kernel of
guest VM and is available starting from Linux kernel 3.8.
Check pre-set maximum for number of combined channels in channel
configuration.
Configuration of OVS and flavor done successfully should result in
maximum being more than '1'):
.. code-block:: console
$ ethtool -l INTERFACE_NAME
To increase number of current combined channels run following command in
guest VM:
.. code-block:: console
$ ethtool -L INTERFACE_NAME combined QUEUES_NR
The number of queues should typically match the number of vCPUs
defined for the instance. In newer kernel versions
this is configured automatically.
Known limitations
~~~~~~~~~~~~~~~~~
* This feature is only supported when using the libvirt compute driver, and the
KVM/QEMU hypervisor.
* Large pages are required for each instance running on hosts with OVS-DPDK.
If large pages are not present in the guest, the interface will appear but
* Huge pages are required for each instance running on hosts with OVS-DPDK.
If huge pages are not present in the guest, the interface will appear but
will not function.
* Expect performance degradation of services using tap devices: these devices
do not support DPDK. Example services include DVR, FWaaS, or LBaaS.