[netperf-talk] Measuring wifi throughput

[Rick Jones]

[keeping the discussion on netperf-talk would be best]

Ekki Plicht (DF4OR) wrote:
> On Sunday 19 July 2009, you wrote:
> 
>>Ekki Plicht (DF4OR) wrote:
>>
>>>Hi.
>>>
>>>New to netperf I wonder if I can really use this tool to measure
>>>throughput of link, in this case a wireless link.
>>>
>>>I used netperf for some initial tests and got a mesured throughput of
>>>about 2.7MBit/s. Not very exciting when looking at the 54Mbit/s link
>>>speed. But over the same wifi link I have access to an ethernet webcam,
>>>and when looking at that I get about 16 to 20MBit/s throughput (measured
>>>with the internal tools of the wifi device).
>>>
>>>Looking at this difference, I ask myself if netperf really is able to
>>>saturate the link or not. Or what other explanation could there be for
>>>the large difference?
>>>netserver is running on a relativly powerful machine, netperf on a slower
>>>machine (P3, 700MHz) with little memory.
>>>
>>>Any ideas?
>>>My ultimate goal is to fine tune the wifi link for best throughput.
>>
>>Given that netperf has been used to saturate 10G Ethernet links, I suspect
>>chances are good we can get it to saturate your 54 Mbit/s wireless link.
>>Probably a matter of things like socket buffer settings and the like. So...
> 
> 
> Ok, great :-)
> That's basically the information I wanted to get. So I know that I have to go 
> looking elswhere in my test setup (config of netperf, setup of testmachines, 
> connections).
> 
> 
> 
>>Not that it is 100% complete, but have you gone through the netperf manual
>>yet?
> 
> 
> Briefly, to get an overview.
> 
> 
> 
>>http://www.netperf.org/svn/netperf2/trunk/doc/netperf.html  should be about
>>as good a link as any for that.
>>
>>On what platform are you running your tests - the OS and revision and such?
> 
> 
> netserver on an AMD 2GHz, running gentoo kernel 2.6.25
> netperf on a notenook with P3 @800MHz, 512MB, running CentOS 5.2 with kernel 
> 2.6.18.
> 

Which is the receiver, and which the sender?

> 
>>What netperf command lines have you tried thusfar?
> 
> 
> netperf -H ip.ad.dr.es
> netperf -H ip.ad.dr.es -t TCP_STREAM (which is the default, I think)

Yes.

> netperf -H ip.ad.dr.es -t TCP_SENDFILE -F somelargefile

I would suggest adding -c -C to those command lines, and then consider 
experimenting with some test-specific -s, -S and -m options, even though in 
theory the default socket buffer sizes for 2.6 kernels should be OK.

Also, you might peruse the attached, which is still evolving.

happy benchmarking,

rick jones

> 
> rgds,
> Ekki

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