Bug 890773

Summary: horribly slow throughput on wifi intel 3945ABG
Product: [Fedora] Fedora Reporter: Jan Teichmann <jan.teichmann>
Component: kernelAssignee: Stanislaw Gruszka <sgruszka>
Status: CLOSED WONTFIX QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 18CC: dcbw, gansalmon, itamar, jklimes, jonathan, kernel-maint, madhu.chinakonda
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2013-06-26 12:56:46 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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dmesg none

Description Jan Teichmann 2012-12-29 22:11:27 UTC 
I have horribly slow throughput on intel 3945ABG dropping down to as low as 10kb/s. Laptop is directly next to access point with 54MBs wifi link. Restarting NetworkManager immediately restores throughput for a few minutes until it drops again and only restarting the NetworkManager temporarily fixes the throughput.  

Name        : NetworkManager
Arch        : x86_64
Epoch       : 1
Version     : 0.9.7.0
Release     : 11.git20121004.fc18
Comment 1 Jirka Klimes 2013-01-08 15:29:13 UTC 
The most probably it is an issue with the driver. What kernel version do you use?
Please include output of 'dmesg' command.

Does
# rmmod iwl3945
# modprobe iwl3945
resolve the issue as well.
Comment 2 Jan Teichmann 2013-01-08 22:14:25 UTC 
It is kernel 3.6.10-4.fc18.x86_64

and yes rmmod/modprobe also fixes the throughput issues for a while.
Comment 3 Jan Teichmann 2013-01-08 22:14:51 UTC 
Created attachment 675113 [details]
dmesg
Comment 4 Josh Boyer 2013-04-01 16:02:07 UTC 
3.6.10 is rather old at this point.  Are you still seeing this with 3.8.x?
Comment 5 Jan Teichmann 2013-04-01 16:17:41 UTC 
3.8.3-201.fc18.x86_64

Yes still the same problem. Wifi throughput on my laptop 1.05 Mbps. Android phone on the same wifi network 8.2 Mbps.
Comment 6 Stanislaw Gruszka 2013-04-03 10:02:05 UTC 
Not sure what Mbps mean, is that Mbits/s or Mbytes/s ? Assuming Mbytes/s: 8MB/s is expected on 11n devices and 2MB/s on old 11g devices, 1MB/s is not that bad, you can check if disable_hw_scan=0 iwl3945 module option help to improve it. If values are in  Mbits/s, there is something wrong on both devices: android & laptop, I suggest update firmware on your router (can do this to help with first case too).
Comment 7 Jan Teichmann 2013-04-03 12:20:48 UTC 
It's in Mbits/s.
The router is 11g and I didn't do the measurement next to the router so there is interference (residential high rise with plenty of other APs).
The 8Mbits/s shows what was possible and what I got on the laptop is 1Mbits/s. Interestingly, improving signal quality increases throughput on the Android device but not on the laptop.

I tried as suggested:
/etc/modprobe.d/iwl3945.conf
  options iwl3945 disable_hw_scan=0

and I am now at stable 6.8 Mbits/s on my laptop.
Comment 8 Jan Teichmann 2013-04-11 14:09:48 UTC 
I have a second laptop with the same wifi module and exactly the same poor wifi throughput. options iwl3945 disable_hw_scan=0 also improved the throughput on this second laptop.
Comment 9 Stanislaw Gruszka 2013-06-26 12:56:46 UTC 
I'm sorry, but I do not see any chance to fix this bug (performance problem with disable_hw_scan=1) - closing with won't fix resolution.