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Date: Tue, 12 Oct 2010 21:22:48 +0300
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Subject: Re: [ath5k-devel] How to profile this strange effect under high load?
From: Nick Kossifidis <mickflemm@gmail.com>
To: Bruno Randolf <br1@einfach.org>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	ath5k-devel@lists.ath5k.org
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Sender: linux-wireless-owner@vger.kernel.org

2010/10/12 Bruno Randolf <br1@einfach.org>:
> Hello!
>
> I am trying to debug a strange effect, I am seeing on soekris net48xx boards
> with two ath5k interfaces:
>
>  * wlan0 [phy0] configured in ad-hoc mode, A band, and it is getting a lot of
> traffic routed thru it
>  * wlan1 [phy1] also configured in ad-hoc mode, G band, but not actively
> sending (no IP address).
>
> I run iperf between two PCs attached by ethernet, UDP 25Mbps and I am sure all
> traffic is routed thru wlan0 (phy0). The load on the SENDING box gets very
> high:
>
> Mem: 27304K used, 99040K free, 0K shrd, 616K buff, 14128K cached
> CPU:   0% usr   0% sys   0% nic   0% idle   0% io   5% irq  93% sirq
> Load average: 1.73 1.01 2.23 2/38 3128
>  PID  PPID USER     STAT   VSZ %MEM %CPU COMMAND
>  2772     2 root     RW       0   0%  71% [phy1]
>  2757     2 root     SW       0   0%  11% [phy0]
>  3128   436 root     R      988   1%   8% top
>    3     2 root     SW       0   0%   5% [ksoftirqd/0]
>    5     2 root     SW       0   0%   3% [events/0]
>   56     2 root     SW       0   0%   1% [bdi-default]
>  1383     1 root     S     1824   1%   0% /usr/bin/oprofiled --session-dir=/r
>
> ...and the interesting thing is that [phy1] - the INACTIVE interface -
> consumes much more CPU time than [phy0] which is actually transmitting.
>
> I have disabled ANI on wlan1, to avoid getting many MIB interrupts, but it
> does not change much.
>
> I have dumped frames on phy1, and all it sees are a few beacon frames.
>
> I have tried wlan1 in managed mode - same effect. The effect is slightly less
> in AP mode, though...
>
> I tried oprofile, but it shows mostly tx related things.
>
> So my question is: How can I find out, what [phy1] is so busy doing? Any ideas
> how to profile this?
>
> Thanks in advance,
> bruno
>

When ph1 is also connected consumes more or less CPU ? What happens If
you just give it an IP address ?


-- 
GPG ID: 0xD21DB2DB
As you read this post global entropy rises. Have Fun ;-)
Nick