8086:422c [Dell Latitude E6510] iwlwifi: tx speed regression with kernel 3.11.0-15-generic

[Øyvind Stegard]

Kernel 3.11.0-15-generic appears to regress iwlwifi performance significantly. I get about 400-500KiB/s sustained transfer rate with 3.11.0-15-generic, while speed is over 7MiB/s with either 3.11.0-12-generic or mainline kernel v3.11.10.3-saucy (same access point).

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: linux-image-3.11.0-15-generic 3.11.0-15.23
ProcVersionSignature: Ubuntu 3.11.0-15.23-generic 3.11.10
Uname: Linux 3.11.0-15-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: oyvind 2102 F.... pulseaudio
 /dev/snd/controlC0: oyvind 2102 F.... pulseaudio
Date: Tue Jan 21 21:13:24 2014
HibernationDevice: RESUME=UUID=0f94207f-b6d7-4b98-8f13-eaaeebb896b1
InstallationDate: Installed on 2013-11-02 (80 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: Dell Inc. Latitude E6510
MarkForUpload: True
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcEnviron:
 LANGUAGE=nb_NO:nb:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=nb_NO.UTF-8
 SHELL=/bin/bash
ProcFB:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-15-generic root=UUID=7816e956-27c6-48c4-9ce2-3b22b5842157 ro quiet nosplash nouveau.perflvl_wr=7777
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-3.11.0-15-generic N/A
 linux-backports-modules-3.11.0-15-generic N/A
 linux-firmware 1.116.1
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/05/2013
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A16
dmi.board.name: 0N5KHN
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA16:bd12/05/2013:svnDellInc.:pnLatitudeE6510:pvr0001:rvnDellInc.:rn0N5KHN:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E6510
dmi.product.version: 0001
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[penalvch (penalvch)]

Øyvind Stegard, thank you for reporting this and helping make Ubuntu better. Could you please confirm this issue exists with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ . If the issue remains, please just make a comment to this.

If reproducible, could you also 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-3.13

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.

[Øyvind Stegard (oyvindstegard)]

Latest desktop image from http://cdimage.ubuntu.com/daily-live/current/ (using kernel 3.13.0-4-generic) works great – no problems with wifi speeds (close to 10MiB/s sustained for both tx/rx).

[Øyvind Stegard (oyvindstegard)]

As mentioned in bug description, the mainline kernel build:

 v3.11.10.3-saucy/ 16-Jan-2014 10:53

from http://kernel.ubuntu.com/~kernel-ppa/mainline/ does not have the problem.

[penalvch (penalvch)]

Øyvind Stegard, would you need a backport to a release prior to Trusty, or may this be closed as Status Invalid?

[Øyvind Stegard (oyvindstegard)]

For Ubuntu Trusty the bug is invalid.

For Ubuntu 13.10, no, definitely not invalid, and a backport would be nice. I thought perhaps the extended stable releases 3.11.10.N would be made available in kernel updates for Ubuntu 13.10 ? If they are, then this problem will likely disappear, since the mainline kernel 3.11.10.3 works OK. (Although I do not know which commit between 3.11.10 and 3.11.10.3 that fixes the problem.)

[penalvch (penalvch)]

Øyvind Stegard, thank you for taking the time to report this bug and helping to make Ubuntu better. However, I am closing it because as per your test in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1271307/comments/4 the bug has been fixed in the latest development version of Ubuntu - Trusty Tahr.

This is a significant bug in Ubuntu. If you need a fix for the bug in previous versions of Ubuntu, please perform as much as possible of the SRU Procedure [1] to bring the need to a developer's attention.

[1]: https://wiki.ubuntu.com/StableReleaseUpdates#Procedure

[Øyvind Stegard (oyvindstegard)]

If anyone else lands here and wonders what the status is in Ubuntu 13.10:
Bug is fixed in kernel 3.11.0-17-generic 3.11.0-17.30 for me. I downloaded and installed it from the Canonical Kernel team PPA:
https://launchpad.net/~canonical-kernel-team/+archive/ppa

I guess it will appear in -proposed eventually ..