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

[Pete Heist <pete@eventide.io>]

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> On Apr 24, 2018, at 1:54 PM, Toke Høiland-Jørgensen <toke@toke.dk> wrote:
> 
> Pete Heist <pete@eventide.io <mailto:pete@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’...

> 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. :)

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...

Cabins 12 and 20 hang off the same gateway (which are all on the same channel, obviously). That will mean more collisions between them. Cabin 28 is the only repeater on its gateway, so is likely to be better. It’s an interesting setup from the standpoint that it’s not very large, but tests a few different single channel repeater scenarios.

>> Overall it would be nice to know, in a typical real-world setup, how
>> much is WiFi latency is due to bufferbloat, and how much to the
>> physical layer?
> 
> On ath9k bufferbloat should be more than 10-20ms or so.

My pings can definitely be in the ether for longer than that, for some reason… :)


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