[Codel] drop state short-circuit...

[Jonathan Morton]

The logic is that if the stored count was effectively controlling the
queue, we want to keep using that value if the network is still under
load.  If 16 intervals (1.6 seconds) pass without re-entering drop state,
we can assume the link is no longer saturated (by this flow) and reset
count.

I think the value 16 itself is mostly arbitrary.

I'm a bit skeptical of the way count is saved and restored in the reference
versions - it's hard to follow.  Cake's version explicitly keeps the old
value, but halves it, allowing it to grow back to its original value if
required.  It would also be reasonable to scale the backoff with time,
rather than thresholding it.

- Jonathan Morton
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/codel/attachments/20150811/af419d6a/attachment-0002.html>