Pete Heist <
peteheist@gmail.com> writes:
I’ll mention one example I noticed of the kind of adjustment that
probably can’t be done from the qdisc layer today. On page 3 from
http://pollere.net/Pdfdocs/noteburstymacs.pdf:
"In addition to increasing the interval by the waiting delay s,
another adjustment might be useful for certain kinds of bursty MACs.
If the MAC is a request-and-grant type, as wifi in infrastructure
mode, cable modems and some satellite modems, the allocation of bytes
or packets that can be sent during each transmission slot is generally
known at the beginning of transmission and may vary for each
transmission slot. In that case, it MAY be useful to use that value
instead of the MTU value to reset first_above_time_."
Yeah, we've had this issue with CoDel when the per-station WiFi rate
drops too low (this is a function of both signal quality and number of
stations). As a temporary fix, I just fiddled with the target until
CoDel stopped being too aggressive, but that is not a proper solution,
and so has not been upstreamed. I'm planning to get back around to
fixing that properly at some point... Problem is that it is not always
the case that "the allocation of bytes or packets that can be sent
during each transmission slot is generally known". For ath9k we could
get at this information at dequeue time, but for ath10k, only the
firmware knows ahead of time...
-Toke
