[ath9k-devel] oprofile the ath9k for low throughput rate and 3 questions

From: Dave Taht <d@teklibre.org>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] oprofile the ath9k for low throughput rate and 3	questions
Date: Wed, 28 Apr 2010 08:17:47 -0600	[thread overview]
Message-ID: <4BD8438B.4070503@teklibre.org> (raw)
In-Reply-To: <8CCAE3CBA5A9F88-AB4-97F2@webmail-m009.sysops.aol.com>

On 04/19/2010 07:05 PM, oiioeu at aol.com wrote:
>
> I got avg. 60Mbps of the throughput rate by iperf testing and had the 
> testing environment like below:
>
>
> OpenWrt:                       r18529 (I tried the latest r20851  and 
> the throughput rate could be even worse )
> AP && STA h/w platform: IXP425
> wireless module:             AR9280( 11na, HT40 )
> wireless driver: ath9k version matched OpenWrt r18529
> topology is like:               PC1 - STA - AP - PC2 ( ethernet 
> connection between PC1 and STA, AP and PC2, and the wireless
>                                       connection between STA and the 
> AP. iperf client on PC1 and iperf server on PC2 )
>
> then I added oprofile support to this throughput rate testing and had 
> the throughput rate decrease to avg 8Mbps, here are my questions:
> 1. whether the avg. 8Mbps of the throughput after adding the oprofile 
> support seemed to be reasonable?
> 2. why there were the warning messeges at the beginning of the 
> opreport result and does it matter or not?
> 3. anyone could point me is there anything abnormal from the opreport 
> messeges that lead to the low throughput in my case?
> the oprofile log are attached

Interesting. I've been meaning to get around to oprofiling my hardware 
(nanostation M5) one of these days  as I'd noted that I was achieving 
~70Mbit via iperf and seeing (via top) that the hardware was spending 
70% of its time in the "sirq" state. (whether or not that was the 
wireless or wired drivers doing that, I don't know).

oprofile tends to be high overhead unless there is special on-chip 
counter support.

As for this particular oprofile, I don't know, but it looks like 
ath9k_ioread32 is a good candidate for optimization, even without the 
huge oprofile slowdown....

>
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