On Mon, Jan 30, 2017 at 8:17 AM, Toke Høiland-Jørgensen <t...@toke.dk> wrote: > Klaus Kinski <jpo234-1vilx0x+lbkelga04la...@public.gmane.org> writes: > >> Hello all, >> >> this is a blast from the past, but something that still bothers me. >> I have two systems with Atheros/QCA cards: >> >> System A: >> OS and driver: Linux 3.18.36 with last Madwifi/sample code from trunk >> >> WLAN card: AR5413 (Senao EMP-8602 PLUS-S) >> >> System B: >> OS and driver: Linux 3.18.36 with mac80211/minstrel and ath9k from >> backports-4.2 >> >> WLAN card: AR9280 (Compex WLE200NX) >> >> While doing the performance measurements both systems are connected to a >> reference system >> >> with a HF cable, so there should be no outside influences. >> >> Both systems are running in 802.11a mode on channel 40. >> The following table shows 802.11 data packets sent from system A and B >> generated by >> >> iperf in UDP mode over a 2s interval: > > What version of iperf, and configured to which rate? Some versions of > iperf will send its traffic in very large bursts (see > http://burntchrome.blogspot.se/2016/09/iperf3-and-microbursts.html?m=1) > which could cause the queue inside ath9k to overflow (it is only 123 > packets pre-4.10). > > Did you try the latest mac80211/ath9k from 4.10? The queueing structure > changed dramatically, which would impact this, at least if it's a queue > overflow problem...
Packet captures would be helpful. Aircaps, if possible, also. > -Toke -- Dave Täht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org
