Re: [PATCH net-next v8 2/3] net: dsa: mv88e6xxx: use the hw tx queues

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 18 Aug 2026 10:59:35 +0200 Cedric Jehasse wrote:
> > Pretending that a DSA device has multiple Tx queues _from the stack_
> > makes no sense. You should be offloading PRIO as the root qdisc,
> > like mlxsw does. Then the rate limiters should be attached as children
> > of PRIO.  
> 
> This patch follows what the implementation i found in other dsa drivers.
> mlxsw seems to be the only driver handling TC_SETUP_QDISC_PRIO.
> Wouldn't that mean setting up cbs for a mv88e6xxx switch would use different
> tc commands than setting it up for another dsa switch (prio vs mqprio)?
> Is your comment specific to this driver, or for dsa drivers in general?

Maybe Vladimir can comment why he picked mqprio. He probably explained
it to me and I forgot.

My mental model is that mqprio offload is for the host ("NIC", IOW host
traffic egress). But if you're configuring a switch where most of the
traffic is internally forwarded within the ASIC. We should have a way
to report stats and offload status. There's no need to pretend we have
multiple host queues and waste memory.