Merge branch 'multi-queue-aware-sch_cake'

Merge branch 'multi-queue-aware-sch_cake'

 says:

====================
Multi-queue aware sch_cake

This series adds a multi-queue aware variant of the sch_cake scheduler,
called 'cake_mq'. Using this makes it possible to scale the rate shaper
of sch_cake across multiple CPUs, while still enforcing a single global
rate on the interface.

The approach taken in this patch series is to implement a separate qdisc
called 'cake_mq', which is based on the existing 'mq' qdisc, but differs
in a couple of aspects:

- It will always install a cake instance on each hardware queue (instead
  of using the default qdisc for each queue like 'mq' does).

- The cake instances on the queues will share their configuration, which
  can only be modified through the parent cake_mq instance.

Doing things this way simplifies user configuration by centralising
all configuration through the cake_mq qdisc (which also serves as an
obvious way of opting into the multi-queue aware behaviour). The cake_mq
qdisc takes all the same configuration parameters as the cake qdisc.

An earlier version of this work was presented at this year's Netdevconf:
https://netdevconf.info/0x19/sessions/talk/mq-cake-scaling-software-rate-limiting-across-cpu-cores.html

The patch series is structured as follows:

- Patch 1 exports the mq qdisc functions for reuse.

- Patch 2 factors out the sch_cake configuration variables into a
  separate struct that can be shared between instances.

- Patch 3 adds the basic cake_mq qdisc, reusing the exported mq code

- Patch 4 adds configuration sharing across the cake instances installed
  under cake_mq

- Patch 5 adds the shared shaper state that enables the multi-core rate
  shaping

- Patch 6 adds selftests for cake_mq

A patch to iproute2 to make it aware of the cake_mq qdisc were submitted
separately with a previous patch version:

https://lore.kernel.org/r/20260105162902.1432940-1-toke@redhat.com
====================

Link: https://patch.msgid.link/20260109-mq-cake-sub-qdisc-v8-0-8d613fece5d8@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>