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

[Pete Heist]

> On Apr 24, 2018, at 3:51 PM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> 
> 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.

If it’s the ratio of "AMPDUs Completed” to "AMPDUs Retried” or “AMPDUs XRetried” we’re looking at, there’s a stark difference between Cabin 12 and Cabin 28. That said, they have quite different traffic patterns, so I’ll have to evaluate this in a situation where traffic patterns are more similar...

Cabin 12 (worst, two repeaters on gateway, NLOS):

# cat /sys/kernel/debug/ieee80211/phy0/ath9k/xmit
                            BE         BK        VI        VO

MPDUs Queued:            23330        735       112    304318
MPDUs Completed:       2096742       1468       144   6622260
MPDUs XRetried:          11932        509        74    274653
Aggregates:            1548313      31541       499         0
AMPDUs Queued HW:            0          0         0         0
AMPDUs Completed:      9674195     204610     22667         0
AMPDUs Retried:        1298897      22613      1025         0
AMPDUs XRetried:         45898       1189       120         0
TXERR Filtered:           7893         96         7         4
FIFO Underrun:               3          0         0        60
TXOP Exceeded:               0          0         0         0
TXTIMER Expiry:              0          0         0         0
DESC CFG Error:              0          0         0         0
DATA Underrun:               1          0         0         0
DELIM Underrun:              1          0         0         0
TX-Pkts-All:          11828767     207776     23005   6896913
TX-Bytes-All:       4193674267  197040003   23478961787460234
HW-put-tx-buf:         5318127     133067     23506   6395453
HW-tx-start:                 0          0         0         0
HW-tx-proc-desc:       5690166     132905     23507   6891740
TX-Failed:                   0          0         0         0

Cabin 28 (best, one repeater on gateway, LOS):

# cat /sys/kernel/debug/ieee80211/phy0/ath9k/xmit
                            BE         BK        VI        VO

MPDUs Queued:            23164        335         2   6929001
MPDUs Completed:       3218272        782        50   9311052
MPDUs XRetried:           6036        250         2   1821270
Aggregates:            6427093      20892        12         0
AMPDUs Queued HW:            0          0         0         0
AMPDUs Completed:    100430860     189959    375988         0
AMPDUs Retried:        1112896       8011        27         0
AMPDUs XRetried:         33862        449         2         0
TXERR Filtered:           2428        122         0        37
FIFO Underrun:               0          0         0         2
TXOP Exceeded:               0          0         0         0
TXTIMER Expiry:              0          0         0         0
DESC CFG Error:              0          0         0         0
DATA Underrun:               0          0         0         0
DELIM Underrun:              0          0         0         0
TX-Pkts-All:         103689030     191440    376042  11132322
TX-Bytes-All:       2783223251  210905451  601627081919930466
HW-put-tx-buf:        16245494     109264    376059  10911913
HW-tx-start:                 0          0         0         0
HW-tx-proc-desc:      16282116     109333    376056  11131555
TX-Failed:                   0          0         0         0

>> 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...

Could that cause mean RTT to go up 10x? :) In combination with having two repeaters on one gateway…