netperf was used without any special tuning parameters. Usually we start
two processes on two hosts which start (almost) simultaneously, last for
20-60 seconds and simply use UDP_STREAM (works well) and TCP_STREAM, i.e.
on 192.168.0.202: netperf -H 192.168.2.203 -t TCP_STREAL -l 20
on 192.168.0.203: netperf -H 192.168.2.202 -t TCP_STREAL -l 20
192.168.0.20[23] here is on eth0 which cannot do jumbo frames, thus we
use the .2. part for eth1 for a range of mtus.
The server is started on both nodes with the start-stop-daemon and no
special parameters I'm aware of.
So long as you are relying on external (netperf relative) means to
report the throughput, those command lines would be fine. I wouldn't be
comfortably relying on the sum of the netperf-reported throughtputs with
those comand lines though. Netperf2 has no test synchronization, so two
separate commands, particularly those initiated on different systems,
are subject to skew errors. 99 times out of ten they might be epsilon,
but I get a _little_ paranoid there.
There are three alternatives:
1) use netperf4. not as convenient for "quick" testing at present, but
it has explicit test synchronization, so you "know" that the numbers
presented are from when all connections were actively transferring data
2) use the aforementioned "burst" TCP_RR test. This is then a single
netperf with data flowing both ways on a single connection so no issue
of skew, but perhaps an issue of being one connection and so one process
on each end.
3) start both tests from the same system and follow the suggestions
contained in :
<http://www.netperf.org/svn/netperf2/tags/netperf-2.4.4/doc/netperf.html>
particluarly:
<http://www.netperf.org/svn/netperf2/tags/netperf-2.4.4/doc/netperf.html#Using-Netperf-to-Measure-Aggregate-Performance>
and use a combination of TCP_STREAM and TCP_MAERTS (STREAM backwards) tests.
happy benchmarking,
rick jones
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