[Codel] fq_"codel" in apple's gear

[Jonathan Morton]

> On 14 Oct, 2023, at 8:23 pm, Dave Taht <dave.taht at gmail.com> wrote:
> 
> I would really like someone with a fresh set of eyeballs to review the
> "codel"  portion of apple's latest code drop here:
> 
> https://www.linkedin.com/feed/update/urn:li:activity:7118969694987935744/

So far as I can tell, it still implements DRR++ (with a comment referencing RFC-8290), but not Codel (there's also no comment referencing RFC-8289).  There's at least one function for handling ECN which is simply not called, at least not in that source file.

In fact, I looked in the header to see where an ECN mark counter was defined.  It is referenced in essentially three places:  the definition, an extraction for reporting to userspace, and an increment - in a function implementing L4S marking, not Codel.

A similar counter for "early dropped" packets is incremented only when packets have to be dropped in an emergency because the queue is *full*.  That's the other counter I would expect to be touched by an AQM implementation.

So, no tangible improvement that I can find easily.

 - Jonathan Morton