[ovs-discuss] QoS: linux- QoS configuration reset when port enslaved to ovs bridge

[Reshma Sreekumar]

Hello All,

I see a peculiar behavior where the following steps resets the QoS
configuration on the netdevice:

*sudo ip link add dummy0 type dummy*
*sudo tc qdisc add dev dummy0 root handle 1: htb default 1*
*sudo ovs-vsctl add-port global_fwbr dummy0*

i.e. when a port with linux htb config having qdisc "1:" is added to ovs
bridge, the qdisc is reset to default type ('noqueue').

*However, this is only true for qdisc "1:" and not for any other qdiscs!*

On further checking the code, it looks like *netdev_linux_set_qos*
eventually calls tc_del_qdisc for this port due to a mismatch in *new_ops*
and *netdev->tc->ops*!

And eventhough the description of *tc_del_qdisc* says that it's equivalent
to `tc qdisc del dev <name> root`, it's not so! tc_del_qdisc only deletes
the qdisc with handle "1:0" and nothing else!

So, what exactly is the expected behaviour? *Is it a valid configuration to
have a port with its own linux htb configuration to be enslaved into an ovs
bridge while the configs remain intact?*

Thanks in advance!

Thanks,
Reshma
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