UDP throughput problems with WDS and ath10k

[Xue Liu]

Hello,

I have test throughput with different 3  parameters. But the results are 
similar. The data rate from PC via  Client to the AP decreases 
significantly comparing with the reverse direction.

During the test I also obverse the CPU load of client and AP. When the 
data is sent from PC, the AP has ~2% CPU load, ~63 nic and ~25% sirq. 
The client has ~0% CPU load ~78% nic and ~20% sirq. When the data sent 
from AP, the AP has ~1% cpu ~69% nic and 7% sirq. The client has ~0% 
cpu, 76% nic and ~24% sirq.

The test diagram is shown as

PC(GbE) --- (GbE)WDS Client (Wireless) --- (Wireless) WDS AP.

Did anyone else tries with such setup ?


On 23/03/16 18:20, Ben Greear wrote:
> On 03/23/2016 09:54 AM, Michal Kazior wrote:
>> On 23 March 2016 at 11:53, Xue Liu <xue.liu at dks-koeln.de> wrote:
>>> Hello everyone,
>>>
>>> Now I am doing point to point  throughput test using  and ath10k. The
>>> hardwares are clearfog A1 board with armada 388 and WLE900VX 
>>> (QCA9880). The
>>> OpenWRT trunk is running on it.
>>>
>>> At first I did UDP throughput test ( WDS AP <---> WDS Client ) with 
>>> iperf3
>>> server on the WDS AP. The throughput is approx 630 Mbps.  But if the 
>>> server
>>> sends the data, the throughput will rise to 700 Mbps.  I did the
>>> bidirectional test for many times. The UDP data transferring from AP 
>>> side
>>> always has 70 - 80 Mbps more throughput.
>>>
>>> In the same situation, I did UDP throughput test between PC and WDS 
>>> AP ( PC
>>> <---->WDS Client <----> WDS AP ) . The PC is connected with the WDS 
>>> client
>>> via GbE port.  I have found a more interesting result. The data 
>>> throughput
>>> is about 678 Mbps when the data is transmitted from AP to PC. There is
>>> almost no performance loss. But the throughput is only about 425 
>>> Mpbs from
>>> PC to AP.
>>>
>>> Can anyone give me some advises or some info about the reason and 
>>> how to
>>> improve the transmitting performance from PC to AP side. Thank you.
>>
>> This is weird. Did you check CPU utilization on all involved devices
>> (PC, WDS Client, WDS AP)? Did you try tweaking iperf parameters, e.g.
>> number of threads, buffer sizes? Playing around with some parameters
>> could narrow down the problem.
>>
>> Normally I would expect the reverse performance drop (i.e. slower
>> performance when traffic is generated locally on WDS Client).
>
> I don't know about WDS, but we definitely see slower upload (from 
> station perspective)
> than download rates, using identical hardware for AP and STA devices.
>
> Patches posted to ath10k list yesterday claim to resolve at least some 
> of this,
> but I have not tested those yet...
>
> Thanks,
> Ben
>
>