[ath9k-devel] Performance degradation when monitor interface is enabled

[Ali Abedi <a2abedi@uwaterloo.ca>]

Hi,
I am writing this response to my own question since I have found a
workaround for this problem and this may help others as well.
So the problem is that if you have an interface wlan0 in managed mode
and then add another interface wlan1 in monitor mode it lowers your
outgoing throughput. It does not affect the incoming traffic though. The
trick is to add the monitor interface wlan1 then remove wlan0 by using
"iw dev wlan0 del" and then create wlan0 again. This way the incoming
and outgoing traffic is not affected by the monitor interface. This can
be caused by a bug in the driver. Those folks who know more about this
part of the driver may figure out what is going on after seeing this
solution.

Best,
Ali

On 23/10/2012 3:06 PM, Ali Abedi wrote:
> Hello,
>
> I asked this question once before but didn't get a satisfying answer. In
> our experiments, with two laptops running Ath9k driver we get about 29
> Mbps bandwidth (802.11g configuration  + UDP traffic), but when the
> monitor mode interface is enabled on the sender the throughput drops to
> 25 Mbps. This is not a performance issue. The performance is unaffected
> if monitor mode interface is enabled on the receiver (no monitor
> interface on sender). I really appropriate your answer.
>
> Regards,
> Ali Abedi
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