[ath9k-devel] ath9k performance issues

[Felix Fietkau <nbd@openwrt.org>]

On 2011-04-05 6:54 PM, Serene Gud wrote:
>
>
>     On 2011-04-05 6:03 PM, Serene Gud wrote:
>
>      >
>      > On 2011-04-05 5:44 PM, Bernhard Walle wrote:
>      > > Hello,
>      > >
>      > > we're using a PCIe AR9280 card on a Octeon MIPS CPU. The system
>      > > that does the transmission has a high CPU utilization:
>      > >
>      > > iperf in UDP mode with 50M bandwith has ~90 % CPU utilization
>     with a
>      > > high softirq proportion.
>      > >
>      > > Using an Intel card (5300) has a lower CPU utilization (~60 %),
>      > but it's
>      > > no option to use it because the Linux driver has no access point
>      > mode.
>      > >
>      > > Are there any tweaks to decrease the CPU utilization with the ath9k
>      > > driver? Any recommendations for the application to send the network
>      > > packets more efficient?
>      > What kernel version are you using? Are you using the in-kernel
>     ath9k or
>      > are you using compat-wireless? I have added quite a few performance
>      > optimizations over time, as I'm working with much slower MIPS
>     CPUs than
>      > the octeon.
>      > In my tests, a 300 MHz MIPS 24K CPU is good enough for handling
>     around
>      > 90 mbit/s of traffic with only around 70% CPU utilization.
>      >
>      > - Felix
>      >
>      >
>      > Now thats interesting Felix :) , how have you managed to get all
>     these?
>     What do you mean with 'get all these'?
>
>     - Felix
>
>
>     Sorry, I am new to these things; what I wanted to ask you was that
>     with the kind of CPU info that you have; how were you able to get 90
>     mbit/s of traffic. I am using a much faster CPU with 1.66 Ghz 512K
>     still I usually get 65mbit/s. I am using in-kernel ath9K. Are you
>     using compat-wireless? Are there any other changes that you have
>     made to your system?
The device I used was using an AR7130 MIPS CPU. I set it up as an access 
point (with 4addr/wds mode enabled), then used another device as a 
4-addr client. Both were set up for bridging wireless to wired.
After that I ran iperf TCP sessions between two laptops (each connected 
to one of the embedded devices).

>     I have no idea if we can make the tx bitrate stable? If you have
>     done that, kindly share.
Are you using the ath9k rate control or are you using minstrel_ht? My 
tests were done with minstrel_ht. You can enable it by disabling the 
config option for the ath9k rate control.

- Felix