low TCP throughput with 80MHz channel width

[Iñaki Pascual]

Thanks for the tip Ben. We have moved to 'reno' and tried several window 
sizes but we are still on max. 35 Mbps which is too low.

Bests,

Iñaki

On 22/04/16 17:40, Ben Greear wrote:
> Use 'reno' instead of cubic TCP congestion control, cubic is broken 
> with ath10k.
>
> Thanks,
> Ben
>
> On 04/22/2016 08:32 AM, Iñaki Pascual wrote:
>> Hi everyone,
>>
>> we have configured two boxes with 802.11ac NICs to work in channel 48 
>> (5240 MHz), ad-hoc mode, 80MHz channel width.
>> For UDP traffic we get 300 Mbps bandwith but for TCP we are around 30 
>> Mbps.
>>
>> We have tried other channels with similar results.
>> Throughput for 20 and 40 MHz channel width are ok (20MHz: TCP 21Mbps, 
>> UDP 27Mbps, 40MHz: TCP 82Mbps, UDP 144Mbps).
>>
>> Testing with iperf we have also tried different congestion windows 
>> with no or low improvements.
>>
>> Below are config details and the sequence of commands we are using to 
>> configure the interface.
>>
>> Any ideas on what we may be doing wrong?
>>
>> Bests,
>>
>> Iñaki
>>
>> iw outputs:
>>
>> root at sc227:/home/monet# iw wlan2 info
>> Interface wlan2
>>      ifindex 6
>>      wdev 0x200000001
>>      addr 04:f0:21:18:26:a2
>>      ssid SC226SC227
>>      type IBSS
>>      wiphy 2
>>      channel 48 (5240 MHz), width: 80 MHz, center1: 5210 MHz
>>
>> root at sc227:/home/monet# iw wlan2 station dump
>> Station 04:f0:21:18:26:a8 (on wlan2)
>>      inactive time:    86 ms
>>      rx bytes:    467732521
>>      rx packets:    364249
>>      tx bytes:    1394558
>>      tx packets:    16200
>>      tx retries:    0
>>      tx failed:    0
>>      signal:      -51 dBm
>>      signal avg:    -51 dBm
>>      tx bitrate:    351.0 MBit/s VHT-MCS 4 80MHz VHT-NSS 2
>>      rx bitrate:    526.5 MBit/s VHT-MCS 4 80MHz VHT-NSS 3
>>      authorized:    yes
>>      authenticated:    yes
>>      preamble:    long
>>      WMM/WME:    yes
>>      MFP:        no
>>      TDLS peer:    no
>>      connected time:    3169 seconds
>>
>>
>> config commands:
>>
>> ifconfig wlan2 down
>> iw wlan2 set type ibss
>> ifconfig wlan2 up
>> ifconfig wlan2 10.2.1.7 netmask 255.255.255.0
>> iw wlan2 ibss join SC226SC227 5240 80MHz
>>
>> iperf:
>> root at sc227:/home/monet# iperf -c 10.2.1.6
>> ------------------------------------------------------------
>> Client connecting to 10.2.1.6, TCP port 5001
>> TCP window size: 85.0 KByte (default)
>> ------------------------------------------------------------
>> [  3] local 10.2.1.7 port 48548 connected with 10.2.1.6 port 5001
>> [ ID] Interval       Transfer     Bandwidth
>> [  3]  0.0-10.0 sec  33.1 MBytes  27.7 Mbits/sec
>>
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>
>