[netperf-talk] What is the unit of -b option?

[Rick Jones]

Lei Lu wrote:
> Hi all,
> 
> I am a newbie to netperf. I want to use the -b option to specify how
> many packets that I want to generate during 1 seconds, eg, sending
> 10000pkts/s each packet with size 100bytes. The problem is that I do
> not know the -b unit, I do take a look at the manual, but it is not
> very clear to me.  Is the following command correct?

It is the number of send() calls.

> "netperf -t UDP_STREAM -H 172.16.2.150 -b 10000 -l 180 -- -m 100  -w 1000"

The -w option for the wait time needs to be a global command-like parameter. 
Once that is fixed, then once a second, netperf will attempt to make 10000 
send() calls, each of 100 bytes.  Added to that by the stack will be an 8 byte 
UDP header, a 20 byte IP header, and then a link-layer header - eg 14 bytes if 
Ethernet without VLANs.

It will probably be very bursty.  If your platform supports a finer granularity 
on its interval timer, I would suggest making -w 10 and making -b 100 at which 
point you will have 100 sends every 10 milliseconds.  If your platform can go 
down to a 1 ms interval timer, I would suggest using that and adjusting -b 
accordingly.

Or, if you are not concerned about CPU utilization, you can add --enable-spin to 
the ./configure and rebuild netperf and you might even be able to get down to a 
-b 1 with a suitably small -w option.

happy benchmarking,

rick jones

> 
> Best,
> Lei
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