[Make-wifi-fast] Thoughts on tackling airtime fairness
dave.taht at gmail.com
Wed May 11 12:19:41 EDT 2016
My own foci are going to be around trying to rip every source of
potential latency out of the current system: be it deferred
interrupts, bad rate control information, overlong txops, excessive
retries, insufficient packet loss, busting the block ack window, and
quashing stations grabbing too much airtime...
and then adding back in "bandwidth" from there. We have enough
bandwidth in wifi nowadays, just now narrow enough time slices to feed
many stations sanely.
a somewhat subtle distinction is that aiming for airtime fairness
independently of the behaviors of real traffic is not a goal (for me).
A system handing out 8 stations 8ms each of airtime is "fair", but
handing out 1ms each - or just enough, for example, for my
videoconferencing flow to handle each frame with a single txop - or
getting a new station started faster on some web traffic - is better.
Certainly there is a ton of low hanging fruit to excise, and achieving
something closer to but we ignore multicast, channel scans, and other
oddities to our peril.
I don't, for example, think that aiming for airtime fairness over 1sec
intervals is good, 20-50ms would be way more desirable. And so on.
Getting a good rate control estimate by the second txop used by a
previously idle station would be good. And so on.
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