[Soekris] Atheros maxes out CPU at 24Mb/s on net4801

Flemming Frandsen ff-soekris at partyticket.net
Sat Jun 2 10:07:03 UTC 2007


Sam Leffler wrote:
>> Good to hear, what are those numbers then, using what iperf parameters?
> 
> I've already cited numbers.

I just went over your posts again, and the only number I could find was 
"28Mb/s".

Is that for a net4801 or a much slower machine?
Are the CPUs maxed out or is this limitation of the radio/protocol?

I can certainly see how a limitation in the card or the protocol would 
show up as spent CPU time if the CPU spins while waiting for the card, 
in which case I wouldn't see any improvement by getting a beefier processor.

I'll soon have some results to report, as I'm in the process of ordering 
a set of these 1GHz boards:
http://www.icp-epia.co.uk/index.php?act=viewProd&productId=232

It's no Soekris, but it certainly has a lot more umpf and it's still in 
the same price and power ballpark.


> When someone makes comments like "the Atheros wireless driver relies 
> heavily on the CPU where the Ethernet does not" w/o an ounce of 
> justification then it's FUD.  I'm beginning to think responding to you 
> is similarly productive.

Are you seriously trying to imply that the only reason I'm posting here 
is to discredit the quality of Atheros hardware and your code?


All I'm trying to do is to figure out answers to my questions:

* Is this really all I can hope for with Atheros cards?

I guess this is about it on net4801, without playing unrealistic tricks 
with TCP options and switching to freebsd.


* If it's the card that has been designed to eat CPU then are there
    others that do more work in hardware?

Probably not and I do like Atheros.


* On paper the net5501 looks to be about twice as fast as net4801,
    which is not quite enough to reach the performance I want, how does
    the net5501 CPU perform compared to net4801?

Nobody tried to answer this one, so I'm going to assume that it's about 
twice as fast.


> I wrote the original madwifi code.  I wrote the freebsd ath code. I 
> wrote the hal code that underlies both code bases.  I know how the 
> hardware and software works.  I've profiled all this code and done 
> extensive performance tuning for currently shipping products that use 
> this code. 

I guess that means that I can trust you when you say that it doesn't go 
any faster than 28Mb/s, good to know.


> You clearly haven't a clue who you're talking to.

I know you've worked in movies, but this is a bit over the top.


> As to the linux code base I've already told you that your best bet is to 
> talk to the madwifi folks because they are presently working on reducing 
> the cpu consumption.

Well, I'm trying to do that at the same time, however if I want to talk 
to other people who use Atheros on anemic CPUs then there is no better 
place to post than right here.

Witness the 7 answers I got here, vs. the 1 answer I got on the 
madwifi-users list.

-- 
  Regards Flemming Frandsen - YAPH - http://dion.swamp.dk


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