I have a few boards with Ampak 6256 chipsets which all have an issue
with 2.4GHz AP throughput and I am keen to find out if this is a known
issue or limitation of the chipset. The AP6256 contains a brcm43456 and
I have seen similar performance issues all the way back to Linux v5.2, I
haven't tested any further than that. I have also tried with various
available firmware found around the internet which has made no difference.
If anybody has any input on how to debug or if they know anything about
the issue I would be very interested to hear about it.
Please see some iperf3 throughput results below as examples. These were
conducted in a residential environment with very few other APs in the
vicinity.
AP6256 2.4GHz Channel 11 AP
---------------------------
[root@alarm ~]# cat /etc/hostapd/hostapd.conf
interface=wlan1
driver=nl80211
ctrl_interface=/var/run/hostapd
ssid=test
channel=11
ieee80211n=1
hw_mode=g
ignore_broadcast_ssid=0
Connecting to host 192.168.10.121, port 5201
[ 5] local 192.168.10.1 port 38954 connected to 192.168.10.121 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 1.69 MBytes 14.2 Mbits/sec 112 17.0 KBytes
[ 5] 1.00-2.00 sec 1.12 MBytes 9.38 Mbits/sec 40 15.6 KBytes
[ 5] 2.00-3.00 sec 1.12 MBytes 9.38 Mbits/sec 28 15.6 KBytes
[ 5] 3.00-4.00 sec 1.24 MBytes 10.4 Mbits/sec 22 24.0 KBytes
[ 5] 4.00-5.00 sec 891 KBytes 7.30 Mbits/sec 23 18.4 KBytes
[ 5] 5.00-6.00 sec 1.49 MBytes 12.5 Mbits/sec 36 15.6 KBytes
[ 5] 6.00-7.00 sec 1.12 MBytes 9.38 Mbits/sec 23 18.4 KBytes
[ 5] 7.00-8.00 sec 1018 KBytes 8.34 Mbits/sec 17 14.1 KBytes
[ 5] 8.00-9.00 sec 1.24 MBytes 10.4 Mbits/sec 28 14.1 KBytes
[ 5] 9.00-10.00 sec 1018 KBytes 8.34 Mbits/sec 29 11.3 KBytes
[ 5] 10.00-11.00 sec 1.12 MBytes 9.38 Mbits/sec 25 15.6 KBytes
[ 5] 11.00-12.00 sec 1.24 MBytes 10.4 Mbits/sec 21 17.0 KBytes
[ 5] 12.00-13.00 sec 1018 KBytes 8.34 Mbits/sec 23 33.9 KBytes
[ 5] 13.00-14.00 sec 1.12 MBytes 9.38 Mbits/sec 35 14.1 KBytes
[ 5] 14.00-15.00 sec 1.37 MBytes 11.5 Mbits/sec 33 24.0 KBytes
[ 5] 15.00-16.00 sec 1.12 MBytes 9.38 Mbits/sec 19 14.1 KBytes
[ 5] 16.00-17.00 sec 891 KBytes 7.30 Mbits/sec 19 8.48 KBytes
[ 5] 17.00-18.00 sec 1.37 MBytes 11.5 Mbits/sec 27 17.0 KBytes
[ 5] 18.00-19.00 sec 1.37 MBytes 11.5 Mbits/sec 26 15.6 KBytes
[ 5] 19.00-20.00 sec 1.12 MBytes 9.38 Mbits/sec 51 17.0 KBytes
[ 5] 20.00-21.00 sec 1018 KBytes 8.34 Mbits/sec 23 5.66 KBytes
[ 5] 21.00-22.00 sec 1.12 MBytes 9.38 Mbits/sec 28 17.0 KBytes
[ 5] 22.00-23.00 sec 891 KBytes 7.30 Mbits/sec 23 9.90 KBytes
[ 5] 23.00-24.00 sec 1.49 MBytes 12.5 Mbits/sec 28 18.4 KBytes
[ 5] 24.00-25.00 sec 1.24 MBytes 10.4 Mbits/sec 25 19.8 KBytes
[ 5] 25.00-26.00 sec 1.12 MBytes 9.38 Mbits/sec 23 9.90 KBytes
[ 5] 26.00-27.00 sec 1.37 MBytes 11.5 Mbits/sec 27 17.0 KBytes
[ 5] 27.00-28.00 sec 1.49 MBytes 12.5 Mbits/sec 22 18.4 KBytes
[ 5] 28.00-29.00 sec 1.37 MBytes 11.5 Mbits/sec 27 14.1 KBytes
[ 5] 29.00-30.00 sec 1018 KBytes 8.34 Mbits/sec 15 18.4 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-30.00 sec 35.6 MBytes 9.96 Mbits/sec 878 sender
[ 5] 0.00-30.00 sec 35.6 MBytes 9.96 Mbits/sec
receiver
iperf Done.
AP6256 5GHz Channel 36 AP
-------------------------
[root@alarm ~]# iperf3 -c 192.168.10.121 -t 30
Connecting to host 192.168.10.121, port 5201
[ 5] local 192.168.10.1 port 50634 connected to 192.168.10.121 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 7.18 MBytes 60.2 Mbits/sec 0 332 KBytes
[ 5] 1.00-2.00 sec 8.76 MBytes 73.5 Mbits/sec 0 553 KBytes
[ 5] 2.00-3.00 sec 9.01 MBytes 75.6 Mbits/sec 0 697 KBytes
[ 5] 3.00-4.00 sec 8.02 MBytes 67.2 Mbits/sec 0 773 KBytes
[ 5] 4.00-5.00 sec 8.82 MBytes 74.0 Mbits/sec 0 911 KBytes
[ 5] 5.00-6.00 sec 8.26 MBytes 69.3 Mbits/sec 0 981 KBytes
[ 5] 6.00-7.00 sec 8.76 MBytes 73.5 Mbits/sec 0 981 KBytes
[ 5] 7.00-8.00 sec 7.83 MBytes 65.7 Mbits/sec 0 981 KBytes
[ 5] 8.00-9.00 sec 9.20 MBytes 77.2 Mbits/sec 0 1.07 MBytes
[ 5] 9.00-10.00 sec 8.20 MBytes 68.8 Mbits/sec 0 1.07 MBytes
[ 5] 10.00-11.00 sec 8.26 MBytes 69.3 Mbits/sec 0 1.13 MBytes
[ 5] 11.00-12.00 sec 8.45 MBytes 70.9 Mbits/sec 0 1.13 MBytes
[ 5] 12.00-13.00 sec 8.51 MBytes 71.4 Mbits/sec 0 1.13 MBytes
[ 5] 13.00-14.00 sec 8.51 MBytes 71.4 Mbits/sec 0 1.13 MBytes
[ 5] 14.00-15.00 sec 8.68 MBytes 72.8 Mbits/sec 0 1.58 MBytes
[ 5] 15.00-16.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.58 MBytes
[ 5] 16.00-17.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 17.00-18.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 18.00-19.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 19.00-20.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.58 MBytes
[ 5] 20.00-21.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 21.00-22.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 22.00-23.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 23.00-24.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 24.00-25.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.58 MBytes
[ 5] 25.00-26.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 26.00-27.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 27.00-28.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
[ 5] 28.00-29.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.58 MBytes
[ 5] 29.00-30.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1.58 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-30.00 sec 253 MBytes 70.7 Mbits/sec 0 sender
[ 5] 0.00-30.00 sec 250 MBytes 69.9 Mbits/sec
receiver
iperf Done.
AP6256 2.4GHz Channel 11 STA
----------------------------
[root@alarm ~]# iw wlan0 info
Interface wlan0
ifindex 3
wdev 0x1
addr c0:84:7d:31:5d:d4
ssid test
type managed
wiphy 0
channel 11 (2462 MHz), width: 20 MHz, center1: 2462 MHz
txpower 31.00 dBm
[root@alarm ~]# iperf3 -c 192.168.11.1
Connecting to host 192.168.11.1, port 5201
[ 5] local 192.168.11.70 port 58330 connected to 192.168.11.1 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 2.71 MBytes 22.7 Mbits/sec 0 146 KBytes
[ 5] 1.00-2.00 sec 3.42 MBytes 28.7 Mbits/sec 0 280 KBytes
[ 5] 2.00-3.00 sec 3.29 MBytes 27.6 Mbits/sec 0 407 KBytes
[ 5] 3.00-4.00 sec 3.04 MBytes 25.5 Mbits/sec 0 553 KBytes
[ 5] 4.00-5.00 sec 3.23 MBytes 27.1 Mbits/sec 0 696 KBytes
[ 5] 5.00-6.00 sec 3.23 MBytes 27.1 Mbits/sec 0 844 KBytes
[ 5] 6.00-7.00 sec 3.73 MBytes 31.3 Mbits/sec 0 892 KBytes
[ 5] 7.00-8.00 sec 2.80 MBytes 23.5 Mbits/sec 1 624 KBytes
[ 5] 8.00-9.00 sec 2.80 MBytes 23.5 Mbits/sec 0 711 KBytes
[ 5] 9.00-10.00 sec 2.80 MBytes 23.5 Mbits/sec 0 711 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 31.0 MBytes 26.0 Mbits/sec 1 sender
[ 5] 0.00-10.04 sec 29.4 MBytes 24.5 Mbits/sec
receiver
iperf Done.