[ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU

[ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU

[oiioeu at aol.com]

 I use IXP425( CPU 533M, 64M RAM ) platform, OpenWrt r18530 with compat-wireless-2009-11-21. 
As an AP, it worked just good I could see an average throughput like 70~80Mbps under HT40( the throughput limited by the 100M ethernet in my test environment). 


As a SU, I tested with a compex wp543 AP and got a throughput like 42~45Mbps under HT40( I think the AP uses HT20 ) so the iw wlan0 station dump on SU shows:

root at OpenWrt:/# iw wlan0 station dump
Station 00:80:48:5f:6f:1e (on wlan0)
        inactive time:  0 ms
        rx bytes:       58959465
        rx packets:     673487
        tx bytes:       2033665611
        tx packets:     1325864
        signal:         -29 dBm
        tx bitrate:     130.0 MBit/s MCS 15

and top shows:

CPU:   0% usr   1% sys   0% nic   3% idle   0% io   1% irq  92% sirq

it seems the SU's CPU has been used up for the throughput testing and turned to be the bottleneck, why?
I run iperf server and client on two PCs seperately connected to the SU and AP by ethernet, there's no significant big process running on the SU.
Any ideas are appreciated. Thank you.



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[ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU

[Felix Fietkau]

On 2010-02-03 9:44 AM, oiioeu at aol.com wrote:
> 
> I use IXP425( CPU 533M, 64M RAM ) platform, OpenWrt r18530 with
> compat-wireless-2009-11-21.
> As an AP, it worked just good I could see an average throughput like
> 70~80Mbps under HT40( the throughput limited by the 100M ethernet in my
> test environment).
> 
> As a SU, I tested with a compex wp543 AP and got a throughput like
> 42~45Mbps under HT40( I think the AP uses HT20 ) so the iw wlan0 station
> dump on SU shows:
OpenWrt r18530 is very old. A lot of things that can affect wifi
performance have changed since that revision. I would recommend building
a current version of OpenWrt and rerunning your tests with it.

- Felix

[ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU

[oiioeu at aol.com]

Thank you.
I did my test again with r19510 the latest one, and I got the avg. throughput like 45Mbps under HT40, the iw showed:

root at OpenWrt:/# iw wlan0 station dump
Station 00:80:48:5f:6f:1e (on wlan0)
        inactive time:  190 ms
        rx bytes:       1234509163
        rx packets:     1156668
        tx bytes:       1141929044
        tx packets:     1115333
        signal:         -48 dBm
        tx bitrate:     130.0 MBit/s MCS 15

root at OpenWrt:/# top -d 1

Mem: 19504K used, 43164K free, 0K shrd, 0K buff, 5356K cached
CPU:   0% usr   1% sys   0% nic   1% idle   0% io   1% irq  94% sirq

the avg. CPU load is like above 90%. meanwhile the AP's CPU load is like 60~70%, is there any other thing that I've forgotten to do to optimize the STA? I specified HT40 in /etc/config/wireless and I have the actuall 130Mbps MCS15, it was actually HT20, as for the throughput 45Mbps, how could it be?



 

-----Original Message-----
From: Felix Fietkau <nbd@openwrt.org>
To: oiioeu at aol.com
Cc: ath9k-devel at lists.ath9k.org
Sent: Thu, Feb 4, 2010 6:18 am
Subject: Re: [ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU


On 2010-02-03 9:44 AM, oiioeu at aol.com wrote:
> 
> I use IXP425( CPU 533M, 64M RAM ) platform, OpenWrt r18530 with
> compat-wireless-2009-11-21.
> As an AP, it worked just good I could see an average throughput like
> 70~80Mbps under HT40( the throughput limited by the 100M ethernet in my
> test environment).
> 
> As a SU, I tested with a compex wp543 AP and got a throughput like
> 42~45Mbps under HT40( I think the AP uses HT20 ) so the iw wlan0 station
> dump on SU shows:
OpenWrt r18530 is very old. A lot of things that can affect wifi
performance have changed since that revision. I would recommend building
a current version of OpenWrt and rerunning your tests with it.

- Felix

 
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[ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU

[oiioeu at aol.com]

 

if I did the iperf testing in the opposite direction, ( I used to set iperf client at PC2 and the server at PC1, not it's the client at PC1 and server at PC2 )
I got a avg. 55Mbps throughput rate, and maximum 60Mbps, it's still not alright for HT40, even for HT20.

why the CPU load is almost full? I guess the throughput would be nice if it doesn't use up the CPU resource.




 

 

-----Original Message-----
From: oiioeu@aol.com
To: nbd at openwrt.org; ath9k-devel at lists.ath9k.org
Sent: Thu, Feb 4, 2010 1:06 pm
Subject: Re: [ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU


Thank you.
I did my test again with r19510 the latest one, and I got the avg. throughput like 45Mbps under HT40, the iw showed:

root at OpenWrt:/# iw wlan0 station dump
Station 00:80:48:5f:6f:1e (on wlan0)
        inactive time:  190 ms
        rx bytes:       1234509163
        rx packets:     1156668
        tx bytes:       1141929044
        tx packets:     1115333
        signal:         -48 dBm
        tx bitrate:     130.0 MBit/s MCS 15

root at OpenWrt:/# top -d 1

Mem: 19504K used, 43164K free, 0K shrd, 0K buff, 5356K cached
CPU:   0% usr   1% sys   0% nic   1% idle   0% io   1% irq  94% sirq

the avg. CPU load is like above 90%. meanwhile the AP's CPU load is like 60~70%, is there any other thing that I've forgotten to do to optimize the STA? I specified HT40 in /etc/config/wireless and I have the actuall 130Mbps MCS15, it was actually HT20, as for the throughput 45Mbps, how could it be?



 

-----Original Message-----
From: Felix Fietkau <nbd@openwrt.org>
To: oiioeu at aol.com
Cc: ath9k-devel at lists.ath9k.org
Sent: Thu, Feb 4, 2010 6:18 am
Subject: Re: [ath9k-devel] weird low throughput avg. 42Mbps && high CPU load as a SU


On 2010-02-03 9:44 AM, oiioeu at aol.com wrote:

> 

> I use IXP425( CPU 533M, 64M RAM ) platform, OpenWrt r18530 with

> compat-wireless-2009-11-21.

> As an AP, it worked just good I could see an average throughput like

> 70~80Mbps under HT40( the throughput limited by the 100M ethernet in my

> test environment).

> 

> As a SU, I tested with a compex wp543 AP and got a throughput like

> 42~45Mbps under HT40( I think the AP uses HT20 ) so the iw wlan0 station

> dump on SU shows:

OpenWrt r18530 is very old. A lot of things that can affect wifi

performance have changed since that revision. I would recommend building

a current version of OpenWrt and rerunning your tests with it.



- Felix


 
 
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