Fwd: DPDK+OVS with OpenStack

Mark Wittling mark.wittling at gmail.com
Sat Oct 10 22:25:39 UTC 2020


Looking for someone who knows OpenStack with OpenVSwitch, and in addition
to that, DPDK with OpenStack and OVS.I am using OpenStack Queens, with
OpenVSwitch. The architecture I am using is documented here:
https://docs.openstack.org/neutron/queens/admin/deploy-ovs-provider.htmlThe
OVS I am using on the Compute Node, is compiled with DPDK, and I have
enabled the datapath to netdev (DPDK) on br-prv (provider network bridge),
and br-tun (tunneling bridge). But these two bridges, br-tun and br-prv,
are patched into another OpenStack bridge, called br-int. I wasn’t actually
sure about whether to tinker with this bridge, and wondered what datapath
it was using.Then, I realized there is a parameter in the
openvswitch_agent.ini file, which I will list here:

# OVS datapath to use. 'system' is the default value and corresponds to the
# kernel datapath. To enable the userspace datapath set this value to 'netdev'.
# (string value)
# Possible values:
# system - <No description provided>
# netdev - <No description provided>
#datapath_type = system
datapath_type = netdev

So in tinkering with this, what I realized, is that when you set this
datapath_type to system or netdev, it will adjust the br-int bridge to that
datapath type.So here is my question. How can I launch a non-DPDK VM, if
all of the bridges are using the netdev datapath type?Here is another
question. What if one of the flavors don’t have the largepages property set
on them? I assumed OpenStack would revert to a system datapath and not use
DPDK for those VM interfaces. Well, I found out in testing, that is not the
case. If you set all your bridges up for netdev, and you don’t set the
property on the Flavor of the VM (largepages), the VM will launch, but it
simply won’t work.Is there no way, on a specific Compute Host, to support
both DPDK (netdev datapaths) and non-DPDK (system datapaths)?Either on a VM
interface level (VM has one interface that is netdev DPDK and another that
is system datapath non-DPDK)?Or on a VM by VM basis (VM 1 has 1 or more
netdev datapath interfaces and VM 2 has 1 or more system datapath
interfaces)?Am I right here? Once you set up a Compute Host for DPDK, it’s
DPDK or nothing on that Compute Host? (edited)
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