wrong "expected throughput" values

[bittorf]

on r48014: no matter if I stress tx or rx or both, the "expected throughput" is always low but the
real speed much higher, e.g.:

cat /sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/64:70:02:d3:24:0c/rc_stats
best   __________rate_________    ________statistics________    ________last_______    ______sum-of________
rate  [name idx airtime max_tp]  [avg(tp) avg(prob) sd(prob)]  [prob.|retry|suc|att]  [#success | #attempts]
        6     0    1648    5.3       5.3     100.0      0.0     100.0   2     0 0            20   20       
        9     1    1112    8.0       8.0     100.0      0.0     100.0   2     0 0             1   1        
       12     2     844   10.5      10.5     100.0      0.0     100.0   2     0 0             1   1        
       18     3     576   15.5      15.5     100.0      0.0     100.0   2     0 0            22   22       
   D   24     4     440   20.4      20.4     100.0      0.0     100.0   2     0 0             1   1        
  C    36     5     308   29.1      29.1      95.5      0.9     100.0   2     0 0            50   51       
 B     48     6     240   37.3      30.5      73.4      1.7     100.0   2     0 0           355   1164     
A   P  54     7     216   41.6      41.6      99.7      0.2     100.0   2     3 3         51469   52307    

Total packet count::    ideal 2600      lookaround 137

root@xiaomi-mini2:~ iw dev wlan0 station get 64:70:02:d3:24:0c
Station 64:70:02:d3:24:0c (on wlan0)
        inactive time:  240 ms
        rx bytes:       111497696
        rx packets:     269063
        tx bytes:       25070029
        tx packets:     43389
        tx retries:     803
        tx failed:      0
        signal:         66 [66, 64] dBm
        signal avg:     59 [-64, 68] dBm
        tx bitrate:     54.0 MBit/s
        rx bitrate:     54.0 MBit/s
        expected throughput:    3.808Mbps
        authorized:     yes
        authenticated:  yes
        preamble:       long
        WMM/WME:        yes
        MFP:            no
        TDLS peer:      no
        connected time: 24563 seconds

root@xiaomi-mini2:~ iw dev wlan0 info
Interface wlan0
        ifindex 8
        wdev 0x2
        addr 64:09:80:7f:48:86
        ssid ffintern.5GHz
        type IBSS
        wiphy 0
        channel 40 (5200 MHz), width: 20 MHz (no HT), center1: 5200 MHz
        txpower 17.00 dBm

i tested the 5ghz radio, other side is a WDR4300.
real speed is constant ~28 mbit TCP tx and ~15mbit TCP rx.

[nbd168]

This is a mac80211 issue, not caused by mt76