[Cake] upstreaming cake in 2017?

[Dave Taht]

I think most of the reasons why cake could not be upstreamed are now
on their way towards being resolved, and after lede ships, I can't
think of any left to stop an
upstreaming push.

Some reasons for not upstreaming were:

* Because the algorithms weren't stable enough
* Because it wasn't feature complete until last month (denatting,
triple-isolate, and a 3 tier sqm)
* Because it had to work on embedded products going back to 3.12 or so
* Because I was busy with make-wifi-fast - which we got upstream as
soon as humanly possible.
* Because it was gated on having the large tester base we have with
lede (4.4 based)
* Because it rather abuses the tc statistics tool to generate tons of stats
* Because DSCP markings remain in flux at the ietf
* We ignore the packet priority fields entirely
* We don't know what diffserv models and ratios truly make sense

Anyone got more reasons not to upstream? Any more desirable features?

In looking over the sources today I see a couple issues:

* usage of  // comments and overlong lines
* could just use constants for the diffserv lookup tables (I just pushed the
   revised gen_cake_const.c file for the sqm mode, but didn't rip out the
   relevant code in sch_cake). I note that several of my boxes have 64
hw queues now
* I would rather like to retire "precedence" entirely
* cake cannot shape above 40Gbit (32 bit setting). Someday +40Gbit is possible
* we could split gso segments at quantum rather than always
* could use some profiling on x86, arm, and mips arches
* Need long RTT tests and stuff that abuses cobalt features
* Are we convinced the atm and overhead compensators are correct?
* ipv6 nat?
* ipsec recognition and prioritization?
* I liked deprioritizing ping in sqm-scripts

Hardware mq is bugging me - a single queued version of cake on the
root qdisc has much lower latency than a bql'd mq with cake on each
queue and *almost* the same throughput.

-- 
Dave Täht
Let's go make home routers and wifi faster! With better software!
http://blog.cerowrt.org