Re: [Cake] second system syndrome

[Jonathan Morton <chromatix99@gmail.com>]

> On 23 Dec, 2015, at 14:41, Dave Taht <dave.taht@gmail.com> wrote:
> 
> Are you actually testing your codel changes at longer RTTs?

The latest set has, so far, only been tested on an ordinary Internet link.  It produced an immediately noticeable improvement on ingress there, implying that it’s controlling the upstream queue better.

I’m reasonably confident, however, that it’ll stand up to more varied tests as well.  Fundamentally, it returns to the standard Codel trigger mechanism under most circumstances, since that’s been shown to work well.

It also adds a new wrinkle that only appears when the queue is growing very quickly, to trigger the signalling early when it’s abundantly clear that it *will* inevitably trigger later.  I think this will particularly help cope with TCP slow-start or, on a long-RTT path, with RTT-independent TCPs like CUBIC.

Feel free to run your own tests.  I need to sleep.

 - Jonathan Morton