On 2012-06-14 4:37 AM, Stephen Donecker wrote: > Hi, > > I am experiencing very high datagram loss between two identical cards > communicating over a single spacial stream in adhoc mode. Using > minstrel_ht rate control the tx bitrate settles at MCS7 150Mbps, and I > get the following iperf results. > > # iperf -c 192.168.11.2 -p 7777 -u -b 150m -t 10 -i 1 > ------------------------------------------------------------ > Client connecting to 192.168.11.2, UDP port 7777 > Sending 1470 byte datagrams > UDP buffer size: 160 KByte (default) > ------------------------------------------------------------ > [ 3] local 192.168.11.1 port 43287 connected with 192.168.11.2 port 7777 > [ ID] Interval Transfer Bandwidth > [ 3] 0.0- 1.0 sec 16.1 MBytes 135 Mbits/sec > [ 3] 1.0- 2.0 sec 16.3 MBytes 137 Mbits/sec > [ 3] 2.0- 3.0 sec 16.3 MBytes 137 Mbits/sec > [ 3] 3.0- 4.0 sec 15.9 MBytes 133 Mbits/sec > [ 3] 4.0- 5.0 sec 16.4 MBytes 138 Mbits/sec > [ 3] 5.0- 6.0 sec 16.0 MBytes 134 Mbits/sec > [ 3] 6.0- 7.0 sec 16.2 MBytes 136 Mbits/sec > [ 3] 7.0- 8.0 sec 16.0 MBytes 135 Mbits/sec > [ 3] 8.0- 9.0 sec 16.2 MBytes 136 Mbits/sec > [ 3] 0.0-10.0 sec 161 MBytes 135 Mbits/sec > [ 3] Sent 115053 datagrams > [ 3] Server Report: > [ 3] 0.0-10.0 sec 92.0 MBytes 77.0 Mbits/sec 0.262 ms 49459/115052 > (43%) > [ 3] 0.0-10.0 sec 1 datagrams received out-of-order > > When I set minstrel_ht to fixed_rate MCS7 I get the following iperf results. > > # iperf -c 192.168.11.2 -p 7777 -u -b 150m -t 10 -i 1 > ------------------------------------------------------------ > Client connecting to 192.168.11.2, UDP port 7777 > Sending 1470 byte datagrams > UDP buffer size: 160 KByte (default) > ------------------------------------------------------------ > [ 3] local 192.168.11.1 port 55776 connected with 192.168.11.2 port 7777 > [ ID] Interval Transfer Bandwidth > [ 3] 0.0- 1.0 sec 17.4 MBytes 146 Mbits/sec > [ 3] 1.0- 2.0 sec 17.4 MBytes 146 Mbits/sec > [ 3] 2.0- 3.0 sec 17.6 MBytes 147 Mbits/sec > [ 3] 3.0- 4.0 sec 17.4 MBytes 146 Mbits/sec > [ 3] 4.0- 5.0 sec 17.5 MBytes 147 Mbits/sec > [ 3] 5.0- 6.0 sec 17.6 MBytes 148 Mbits/sec > [ 3] 6.0- 7.0 sec 17.4 MBytes 146 Mbits/sec > [ 3] 7.0- 8.0 sec 17.4 MBytes 146 Mbits/sec > [ 3] 8.0- 9.0 sec 17.8 MBytes 149 Mbits/sec > [ 3] 0.0-10.0 sec 175 MBytes 147 Mbits/sec > [ 3] Sent 124930 datagrams > [ 3] Server Report: > [ 3] 0.0-10.2 sec 10.2 MBytes 8.39 Mbits/sec 4.527 ms > 117609/124920 (94%) > [ 3] 0.0-10.2 sec 1 datagrams received out-of-order > > In either case the overall throughput and datagram loss percentages are > terrible. I believe overall the datagram loss should be less than a few > percent. Your expectations seem quite wrong. A PHY rate of 150 Mbit/s will not get you anywhere near 150 Mbit/s UDP throughput, there's lots of 802.11 related overhead inbetween. To check some stats on tx rate and retransmissions, take a look at /sys/kernel/debug/ieee80211/phy0/netdev:wlan0/stations/*/rc_stats (without fixed-rate). One reason why the fixed-rate iperf looks so much worse is that it disables aggregation.
- Felix _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
