Hi, if one executes for example "iperf -c 178.62.60.141 -fm -b 100m -u -t 30 -i 10", then after each 10 second interval Iperf client prints out the amount of data it has transferred in mebibytes:
root@vserver:~# iperf -c 178.62.60.141 -fm -b 100m -u -t 30 -i 10 WARNING: option -b implies udp testing ------------------------------------------------------------ Client connecting to 178.62.60.141, UDP port 5001 Sending 1470 byte datagrams UDP buffer size: 0.22 MByte (default) ------------------------------------------------------------ [ 3] local 146.185.187.148 port 37660 connected with 178.62.60.141 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 119 MBytes 100 Mbits/sec [ 3] 10.0-20.0 sec 119 MBytes 100 Mbits/sec [ 3] 20.0-30.0 sec 119 MBytes 100 Mbits/sec [ 3] 0.0-30.0 sec 358 MBytes 100 Mbits/sec [ 3] Sent 255661 datagrams Same is true for TCP. Fact, that transferred data and bandwidth are printed out after the end of each interval and transferred data is sometimes bit more or less than the bandwidth specified with the "-b" flag, should mean that Iperf client actually somehow counts the sent data and doesn't just print the argument of "-b" flag. Still, how does Iperf client count the amount of data it sends? It sure doesn't do this on some low level because if I introduce 10% packet loss with tc, execute "iperf -c 178.62.60.141 -fm -b 100m -u -t 30 -i 10" and then compare the packets Iperf client thought it sent(from Iperf client output) with the amount of packets actually were put to wire(from "ip -s link show dev eth0" output), then Iperf client thought that it sent >250k datagrams while it actually did just bit over 230k. Exactly the same holds true if I police the traffic with tc Token Bucket Filter queuing discipline, i.e. according to Iperf client it has sent out traffic at 100Mbps while actual traffic rate was policed by policer. How does Iperf 2.x client detect the amount of traffic it has sent? Does Iperf client simply count the packets it has passed to Linux network stack? Could somebody point me to the place in source-code where this takes place? thanks, Martin ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
