Wireless performance issues on kernel 3.4.0-1-generic (iwlwifi)

[Vikrant]

I was expecting this to happen but was too lazy on reporting issues on mainline kernels earlier. But now since the 3.4 kernels has made it to quantal repos, I am affected by it.

The issue is that on 3.4 kernels (I have tried all mainline kernels RC1 to RC5), my wireless performance goes for toss.

I am attaching a screenshot as well on current wireless signal. At same location on my previous precise kernel ( 3.2.0.24) the connection speed is around 52 mpbs (average), but on this kernel the connection is very unstable. As I connect (or when system starts up), the connection speed is like 40mbps, and this degrades in a minute or so to 19 mbps, then to 6 mbps and eventually connection becomes crazily slow on 1 mbps.

This is reproducible every time.

Hopefully, apport has collected enough information but I will try to provide some more info as part of description.

$ lspci -v

03:00.0 Network controller: Intel Corporation Centrino Wireless-N + WiMAX 6150 (rev 67)
        Subsystem: Intel Corporation Centrino Wireless-N + WiMAX 6150 BGN
        Flags: bus master, fast devsel, latency 0, IRQ 48
        Memory at f5600000 (64-bit, non-prefetchable) [size=8K]
        Capabilities: <access denied>
        Kernel driver in use: iwlwifi
        Kernel modules: iwlwifi

Let me know what information I can provide to get help resolve this blocking issue, which wont let me try/test kernel 3.4 further.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: linux-image-3.4.0-1-generic 3.4.0-1.3
ProcVersionSignature: Ubuntu 3.4.0-1.3-generic 3.4.0-rc5
Uname: Linux 3.4.0-1-generic x86_64
NonfreeKernelModules: nvidia
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.25.
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: ALC269VB Analog [ALC269VB Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: kx 2169 F.... pulseaudio
 /dev/snd/controlC0: kx 2169 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0xf6a00000 irq 49'
   Mixer name : 'Realtek ALC269VB'
   Components : 'HDA:10ec0269,10431b33,00100100'
   Controls : 24
   Simple ctrls : 13
Card1.Amixer.info:
 Card hw:1 'NVidia'/'HDA NVidia at 0xf4080000 irq 17'
   Mixer name : 'Nvidia GPU 15 HDMI/DP'
   Components : 'HDA:10de0015,10de0101,00100100'
   Controls : 24
   Simple ctrls : 4
Date: Thu May 3 22:20:25 2012
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20110901)
MachineType: ASUSTeK Computer Inc. G74Sx
ProcEnviron:
 LANGUAGE=en_IN
 TERM=xterm
 PATH=(custom, user)
 LANG=en_IN.UTF-8
 SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.4.0-1-generic root=UUID=ad1c5163-5aee-4c62-8395-af61ae2995a7 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.4.0-1-generic N/A
 linux-backports-modules-3.4.0-1-generic N/A
 linux-firmware 1.80
SourcePackage: linux
StagingDrivers: rts5139 mei
UpgradeStatus: Upgraded to quantal on 2011-11-17 (167 days ago)
dmi.bios.date: 09/23/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: G74Sx.203
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: G74Sx
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrG74Sx.203:bd09/23/2011:svnASUSTeKComputerInc.:pnG74Sx:pvr1.0:rvnASUSTeKComputerInc.:rnG74Sx:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: G74Sx
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.

[Vikrant (vikrant82)]

Can't I set affected package to linux-image-3.4.0-1-generic, It gets set to linux automatically with a message - 'linux-image-3.4.0-1-generic' is a binary package. This bug has been assigned to its source package 'linux' instead.

[Vikrant (vikrant82)]

Some more information - The wireless router is a Dlink DIR-615. I have tried setting wireless mode to n , b/g/n , g/n. The signal % shown on router page also diminishes drastically on this kernel.

[Vikrant (vikrant82)]

Screenshot showing gutted connection

[Joseph Salisbury (jsalisbury)]

@Vikrant,

Was there a prior kernel version or Ubuntu release where you didn't see this issue?

[Vikrant (vikrant82)]

Yes, I have not seen this issue on any precise kernel (3.2.0-XX). I bumped into the issue while testing mainline 3.4 RC2, and it kept reproducing through all RCs. Now when 3.4 hit quantal repos, I am seeing the issue again. When I boot back into precise kernel - linux-image-3.2.0-24-generic, I don't see the issue.

[Tim Gardner (timg-tpi)]

Something environmental? I've just tested the same Intel Corporation Centrino Wireless-N + WiMAX 6150 BGN against a Cisco WRT310 and am seeing 96-101 Mbit/sec on both Precise (3.2.0-24.38) and Quantal (3.4.0-1.3).

[Vikrant (vikrant82)]

Security - ? I am on WPA-PSK. Could it be certain wireless configuration ? How can I debug further ? If I could get a graph/table or something which gives me connection speed with time. I could report how connection speed degrades on the two kernels..

[Joseph Salisbury (jsalisbury)]

Vikrant,

If you keep the system in the same location, connected to the same router and reboot into the precise kernel, does the issue go away?

[Vikrant (vikrant82)]

Yes Joseph, that's correct. Connection is stable on precise kernel and very unstable (going up and down and down and up and eventually throttles at 1mbps). I am playing with various router configurations, let me report back..

[Vikrant (vikrant82)]

The issue manifests, as soon as I start to access websites.

Precise kernel is rock solid on around (10mbps internet traffic):

wlan0 IEEE 802.11bgn ESSID:"Kxak"
          Mode:Managed Frequency:2.432 GHz Access Point: 1C:7E:E5:30:E3:DC
          Bit Rate=65 Mb/s Tx-Power=15 dBm
          Retry long limit:7 RTS thr:off Fragment thr:off
          Power Management:off
          Link Quality=43/70 Signal level=-67 dBm
          Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
          Tx excessive retries:1014 Invalid misc:78 Missed beacon:0

3.4.0 has throttled, and I am getting time outs on my websites: (Interesting see Tx-Power, its 0 here)
wlan0 IEEE 802.11bgn ESSID:"Kxak"
          Mode:Managed Frequency:2.432 GHz Access Point: 1C:7E:E5:30:E3:DC
          Bit Rate=1 Mb/s Tx-Power=0 dBm
          Retry long limit:7 RTS thr:off Fragment thr:off
          Power Management:off
          Link Quality=45/70 Signal level=-65 dBm
          Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
          Tx excessive retries:280 Invalid misc:615 Missed beacon:0

[Vikrant (vikrant82)]

Ok I tested with WEP (I had to enable mixed mode g/n to enable WEP).

- On 3.2 kernel, again connection was rock solid at 54 mbps no matter what I browse.
- On 3.4, connection seem to max at 36 mpbs, fluctuates between 6 to 22 mbps on some internet traffic. File transfer rates are lower, but it took more time to get throttled to 1 mbps. But after some time it recovered and is now at around 36 mbps as I am not transferring much. Here I open a youtube video and it goes to 11 mbps and back to 1 mbps(throttled) and recovers to 5.5, staying there. Basically its unstable.

[Vikrant (vikrant82)]

Sorry for the spam. But looks like I am getting lot of "invalid-misc" on newer kernel. I am monitoring connection with

$ watch --interval 5 iwconfig wlan0

[Eric Appleman (erappleman)]

Confirming with the Intel 6230 card.

You need to modprobe with 11n_disable=1 to avoid the bug.

[lonniehenry (lonniehenry-gmail)]

I am seeing this with this kernel. I have used all of the 3.4.0 release candidates up to rc4 with a precise install with no problem. I use a Broadcom card bcm4312.

[Vikrant (vikrant82)]

@Eric The connection is idling at 48mbps and goes to around 36 mbps but is stable with 11n_disable=1 flag on 3.4 kernel. However, same flag keeps connection stable at 54mbps on precise kernel. It looks like, that connection on g is still stabler on precise kernel, although the lock ups are not there any more.

[Vikrant (vikrant82)]

Tried RC 6, Still no luck.

[Joseph Salisbury (jsalisbury)]

This issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report at bugzilla.kernel.org [1]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug.

If you are comfortable with opening a bug upstream, It would be great if you can report back the upstream bug number in this bug report. That will allow us to link this bug to the upstream report.

[1] https://wiki.ubuntu.com/Bugs/Upstream/kernel

[Joseph Salisbury (jsalisbury)]

Please ignore my last comment. I looks like an upstream bug was already opened:
auto-bugzilla.intellinuxwireless.org #2328

[Leslie Viljoen (leslieviljoen)]

This bug makes daily work a real pain - my wifi is constantly going down and I have to press the hardware kill switch twice to get it back up again.

As a work-around, based on the upstream report, I have been running a script to force the adapter into (slower) g-mode:

sudo rmmod iwlwifi
sudo modprobe iwlwifi 11n_disable=1

This script sometimes causes a complete kernel crash, so I have not made it run by default, though it has not caused a crash so far when I run it manually soon after bootup. Perhaps it causes the crash after the adapter has gone through one of its failure cycles?

After the adapter is in g mode I do still get wifi disconnects but they are in the order of less than once a day, so I can at least get some work done.

[penalvch (penalvch)]

bugzilla.intellinuxwireless.org doesn't exist anymore.

[penalvch (penalvch)]

Vikrant, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

Also, could you please test the latest upstream kernel available (not the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.12

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.