[Make-wifi-fast] mesh deployment with ath9k driver changes

Toke Høiland-Jørgensen toke at toke.dk
Tue Apr 24 09:51:32 EDT 2018

Pete Heist <pete at eventide.io> writes:

>> On Apr 24, 2018, at 1:54 PM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
>> Pete Heist <pete at eventide.io <mailto:pete at eventide.io>> writes:
>>> Mean ping time for
>>> cabin 12 is around 200 ms during “active use”, with outliers above 1
>>> second, which is higher than expected. I don’t have data collected on
>>> how many active users that is and what they’re doing, but there could
>>> be 40-50 students around the cabin 12 AP, with however many active "as
>>> is typical for kids”.
>> Hmm, yeah, 200ms seems quite high. Are there excessive collisions and
>> retransmissions?
> Hrm, how would I know that actually? /proc/net/wireless has all zeroes
> in it. I don’t see it anywhere in output from ‘iw’...

Assuming you have debugfs enabled you should be able to get aggregate
statistics from /sys/kernel/debug/ieee80211/phy0/ath9k/xmit - at least
that contains retries, but not backoff data, unfortunately.

There's also the per-station rate data in /sys/kernel/debug/ieee80211/phy0/netdev\:*/stations/*/rc_stats

>> Is the uplink on the same frequency as the clients?
> Most definitely, the OM2P-HS is a single channel (2.4 GHz) device,
> with dual antennas. I was hoping the new driver could make the best of
> this situation. :)

Well, in that situation 'the best' may not be terribly good ;)

> Now, my ping test goes from the gateway straight to the repeater, so
> there’s only one WiFi hop in my ping results. I don’t know how pings
> actually look for clients while the AP is under load. I suppose I’ll
> either have to test that manually when I’m on site, or set up a fixed
> wireless SmokePing instance to simulate a client.
> I wish I could cable everything, but it isn’t physically practical.
> The next possibility is dual channel APs, or separate backhaul links,
> all costing something...

Yeah, a separate backhaul on a different channel would cut you
contention in half, basically. Right now, each transmission has to
occupy the channel twice...


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