Adrian,
Thanks for your reply.
You should first report what hardware, which channel, what configuration, etc.
Ubiquity Routerstation (Atheros AR7161 @ 680MHz)
Ubiquity SR71-15 (Atheros AR9220/AR9280) 802.11n 2T2R
OpenWRT r32347
mode adhoc
channel 157
frequency 5785MHz
channel type HT40+
rate control minstrel_ht
dual stream MCS15 300Mbps
Next is likely looking at the TX and RX side of things.
I have been doing some extensive testing and discovered that a lot of
packets are being dropped on the tx side with few if any drops on the rx
side. With a PHY of 300Mbps I get about 100Mbps UDP.
TX - check short/long retries, what the minstrel_ht rate control
debugging says. It should give you throughput information per rate
that it tries. Look at short/long retry counts.
RX - look at CRC errors.
long_retry_limit 4
short_retry_limit 7
type rate throughput ewma prob this prob this
succ/attempt success attempts
HT20/LGI MCS0 6.6 99.9 100.0 0( 0)
989 990
HT20/LGI MCS1 13.0 99.9 100.0 0( 0)
989 991
HT20/LGI MCS2 19.1 99.9 100.0 0( 0)
1026 1027
HT20/LGI MCS3 25.0 99.9 100.0 0( 0)
1060 1065
HT20/LGI MCS4 36.2 99.6 100.0 0( 0)
1036 1040
HT20/LGI MCS5 46.5 99.9 100.0 0( 0)
959 962
HT20/LGI MCS6 51.2 99.9 100.0 0( 0)
969 973
HT20/LGI MCS7 56.9 99.7 100.0 0( 0)
971 977
HT20/LGI MCS8 13.0 99.9 100.0 0( 0)
969 974
HT20/LGI MCS9 25.0 99.9 100.0 0( 0)
974 977
HT20/LGI MCS10 36.3 99.9 100.0 0( 0)
1007 1014
HT20/LGI MCS11 46.5 99.9 100.0 0( 0)
1017 1020
HT20/LGI MCS12 66.2 99.9 100.0 0( 0)
1058 1062
HT20/LGI MCS13 81.2 99.9 100.0 0( 0)
973 977
HT20/LGI MCS14 90.0 99.9 100.0 0( 0)
966 968
HT20/LGI MCS15 86.8 89.4 100.0 0( 0)
969 976
HT40/LGI MCS0 13.5 99.9 100.0 0( 0)
983 986
HT40/LGI MCS1 26.0 99.9 100.0 0( 0)
996 1000
HT40/LGI MCS2 37.4 99.9 100.0 0( 0)
1014 1018
HT40/LGI MCS3 48.2 99.9 100.0 0( 0)
1026 1033
HT40/LGI MCS4 68.0 99.9 100.0 0( 0)
1059 1062
HT40/LGI MCS5 84.0 100.0 100.0 0( 0)
975 975
HT40/LGI MCS6 93.4 99.9 100.0 0( 0)
970 974
HT40/LGI MCS7 101.0 99.9 100.0 0( 0)
976 978
HT40/LGI MCS8 25.4 97.4 100.0 0( 0)
963 971
HT40/LGI MCS9 48.2 99.9 100.0 0( 0)
975 982
HT40/LGI MCS10 68.0 99.9 100.0 0( 0)
978 985
HT40/LGI MCS11 84.0 100.0 100.0 0( 0)
1014 1014
HT40/LGI MCS12 114.9 99.9 100.0 0( 0)
1049 1051
HT40/LGI MCS13 133.3 99.9 100.0 0( 0)
970 972
HT40/LGI MCS14 148.0 99.2 100.0 0( 0)
983 987
HT40/LGI t MCS15 158.7 99.9 100.0 0( 0)
8419 8533
HT40/SGI MCS0 14.9 99.9 100.0 0( 0)
973 977
HT40/SGI MCS1 28.7 99.9 100.0 0( 0)
993 995
HT40/SGI MCS2 41.1 99.9 100.0 0( 0)
1003 1008
HT40/SGI MCS3 52.9 99.9 100.0 0( 0)
1013 1018
HT40/SGI MCS4 74.0 99.9 100.0 1( 1)
1027 1032
HT40/SGI MCS5 90.9 100.0 100.0 0( 0)
978 978
HT40/SGI MCS6 101.0 99.9 100.0 0( 0)
973 974
HT40/SGI PMCS7 108.6 99.9 100.0 0( 0)
974 976
HT40/SGI MCS8 28.7 99.9 100.0 0( 0)
978 983
HT40/SGI MCS9 52.9 99.9 100.0 0( 0)
978 984
HT40/SGI MCS10 74.0 99.9 100.0 0( 0)
994 998
HT40/SGI MCS11 90.8 99.9 100.0 0( 0)
1017 1019
HT40/SGI MCS12 123.4 99.9 100.0 0( 0)
1056 1066
HT40/SGI MCS13 140.3 99.6 100.0 0( 0)
991 999
HT40/SGI MCS14 158.7 99.9 100.0 0( 0)
18269 18402
HT40/SGI T MCS15 165.2 99.1 98.7 553(560)
10865638 11039921
Total packet count:: ideal 10890621 lookaround 46906
Average A-MPDU length: 4.8
I am not sure where I am to find the short and long retry counts.
In conclusion I discovered that during Tx the CPU load is almost 100%.
Thanks again,
-Stephen
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