Folks testing APs may be interested in iperf 2.0.14 features. It adds support for both capacity (throughput) an speed (latency) measurements with the --trip-times option. It also has support for scheduling transmit start times and -P supports incrementing the destination IP. It's currently in an early field test phase. Code is here https://sourceforge.net/projects/iperf2/ I haven't cross compiled it for openwrt though that might be a good thing to do.
Bob McMahon