[Cerowrt-devel] [Bloat] Comcast upped service levels -> WNDR3800 can't cope...

[Jonathan Morton]

On 29 Aug, 2014, at 9:06 pm, Dave Taht wrote:

> The cpu caches are 32k/32k, the memory interface 16 bit. The rate limiter
> (the thing eating all the cycles, not the fq_codel algorithm!) is
> single threaded and has global locks,
> and is at least partially interrupt bound at 100Mbits/sec.

Looking at the code, HTB is considerably more complex than TBF in Linux, and not all of the added complexity is due to being classful (though a lot of it is).  It seems that TBF has dire warnings all over it about having limited packet-rate capacity which depends on the value of HZ, while HTB has some sort of solution to that problem.

Meanwhile, FQ has per-flow throttling which looks like it could be torn out and used as a simple replacement for TBF.  I should take a closer look and check whether it would just suffer from the same problems, but if it won't, then that could be a potential life-extender for the 3800.

 - Jonathan Morton