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Ticket #2290 (new defect)

Opened 13 years ago

Performance problem (latency + bandwidth) with madwifi-hal-

Reported by: Assigned to:
Priority: critical Milestone:
Component: madwifi: other Version: trunk
Keywords: Cc:
Patch is attached: 0 Pending: 0


I have some latency+bandwidth problem with madwifi using this snapshot: madwifi-hal-

I've compiled and installed it (I'm on Ubuntu Jaunty, and I have used jockey to activate it).

Linux ozzu 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:58:03 UTC 2009 x86_64 GNU/Linux

This is my lsmod:

ath_rate_sample        21888  1 
ath_pci               224832  0 
wlan                  259232  5 wlan_tkip,wlan_scan_sta,ath_rate_sample,ath_pci
ath_hal               339088  3 ath_rate_sample,ath_pci
multipath              16512  0 

When the computer boots, everything seems to work correctly. I get perfect latency (ping times to my AP < 1ms) and perfect bandwidth (an internal speed-test of my ISP shows 6Mbit down and 1Mbit up, which is my nominal bandwidth).

But after a few minutes the situation slows degrades. After 5-10 minutes, ping to the gateway is like this:

PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=3.60 ms
64 bytes from icmp_seq=2 ttl=64 time=8.07 ms
64 bytes from icmp_seq=3 ttl=64 time=2.59 ms
64 bytes from icmp_seq=4 ttl=64 time=6.51 ms
64 bytes from icmp_seq=5 ttl=64 time=1.95 ms
64 bytes from icmp_seq=6 ttl=64 time=6.35 ms
64 bytes from icmp_seq=7 ttl=64 time=6.83 ms
64 bytes from icmp_seq=8 ttl=64 time=6.54 ms
64 bytes from icmp_seq=9 ttl=64 time=3.41 ms
64 bytes from icmp_seq=10 ttl=64 time=1.94 ms
64 bytes from icmp_seq=11 ttl=64 time=9.07 ms
64 bytes from icmp_seq=12 ttl=64 time=5.57 ms
64 bytes from icmp_seq=13 ttl=64 time=2.31 ms
--- ping statistics ---
13 packets transmitted, 13 received, 0% packet loss, time 12016ms
rtt min/avg/max/mdev = 1.948/4.984/9.076/2.360 ms

which is very high compared to the initial < 1ms. Bandwidth tests also show a very noticable degrade: downstream speed goes to maximum 1Mbit (instead of 6Mbit) and upstream bandwidth doesn't go over 128Kbit (instead of 1Mbit).

NOTE: A bit of bkg history in case it helps. Ubuntu Jaunty ships with ath5k. This is where my problems started: I experimented random freezes. Googling around, I saw people that were turning back to madwifi. I tried, and this is the problem I now see. Notice that this wifi card had been working correctly in the past 2 years with whatever kernel+madwifi drivers Ubuntu shipped in the past versions. All the problems arose after the Jaunty upgrade.