[ovs-dev] 8021q module is not loaded when adding vlan through ovs (ovs-vsctl)

Jiri Pirko jiri at resnulli.us
Thu Oct 25 06:34:59 UTC 2018

Wed, Oct 24, 2018 at 10:12:54PM CEST, michaelsh86 at gmail.com wrote:
>I noticed that there is a performance issue when running traffic on a vlan
>interface that was created by OVS.
>If we create a bridge with a vlan interface, the 8021q module is not loaded.
>Then when packets with a 8021q tag arrives, the linux stack can't use the
>vlan ndos (such as gro_recieve) since there is no such vlan device.
>If I perform the same test after loading the 8021q module, I get 2x-5x
>better performance.

Could you please describe why exacly do you think you see this increase?

>I personally test that using tunnels (vxlan) but I think the issue exists
>even without the tunnel.
>*Creating a bridge and vlan interface:*
>ovs-vsctl --no-wait add-br br_0
>ip link set br_0 up
>ovs-vsctl --no-wait add-port br_0 ens5f0
>ovs-vsctl --no-wait add-port br_0 vlan10 tag=10 -- set interface vlan10
>ip link set vlan10 up
>ip addr add <ip> dev vlan10
>run traffic (netperf on the vlan10 interface) and see the result.
>Then do 'modprobe 8021q' and perform the same test -> you will see much
>better numbers.
>I am suggesting to load 80021q module once vlan interface is added through
>similarly as a vlan interface would be created using 'ip link'.

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