Klaus Kinski <jpo234-1ViLX0X+lBKELgA04lAiVw@xxxxxxxxxxxxxxxx> 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... -Toke
