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[Xiao-Long Chen <chillermillerlong@xxxxxxxxxxx>]

The fix for this is to add the following to /etc/modprobe.d/iwlwifi.conf

    options iwlwifi 11n_disable=8

The problem was caused by the following commit, which disabled TX
aggregation by default on the "old" hardware managed by the iwldvm
driver (including our Intel 6300AGN):
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=205e2210daa975d92ace485a65a31ccc4077fe1a

Looking at the commit and output of "modinfo iwlwifi", passing the value
8 to the 11n_disable parameter forces TX aggregation to be enabled
again.

After some basic testing, this has boosted my (upload) transfer speed
from ~20 Mbps to ~100 Mbps (or equivalently, from ~2.5 MB/s to ~ 12
MB/s).

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https://bugs.launchpad.net/bugs/1270208

Title:
  8086:422b [Dell Latitude E6520] linux-image-3.11.0-15-generic appears
  to regress connection speed for iwlwifi

Status in “linux” package in Ubuntu:
  Expired

Bug description:
  I recently installed 13.10 and immediately updated to the latest
  updates via my ethernet work connection.

  Got home and noted that linux-image-3.11.0-15-generic was only able to
  transfer to my local media box via wifi at ~350kB/s (ie. Taking 10+
  minutes for a 300Mb file)

  After trawling the net for a while, the usual solution appeared to be
  "restart with 11n_disable=1 as a module option."

  That didn't solve the issue not did several other suggestions. So I
  reverted to the other kernal installed on my system linux-
  image-3.11.0-12-generic

  After booting that kernel my transfer speeds are ~3MB/s - much saner
  (though I have had things configured so I get closer to 6MB/s)

  Not sure what other info I can provide.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.10
  Package: linux-image-3.11.0-12-generic 3.11.0-12.19 [modified: boot/vmlinuz-3.11.0-12-generic]
  ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
  Uname: Linux 3.11.0-12-generic x86_64
  ApportVersion: 2.12.5-0ubuntu2.2
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  carlos     2193 F.... pulseaudio
   /dev/snd/controlC0:  carlos     2193 F.... pulseaudio
  Date: Fri Jan 17 23:59:56 2014
  HibernationDevice: RESUME=UUID=0fbe8395-5e8d-430f-823c-b5408451c73e
  InstallationDate: Installed on 2014-01-14 (3 days ago)
  InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
  MachineType: Dell Inc. Latitude E6520
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_AU:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_AU.UTF-8
   SHELL=/bin/bash
  ProcFB:
   0 inteldrmfb
   1 nouveaufb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-12-generic root=UUID=22c75466-3cb5-416a-9513-8debe4246bcd ro quiet splash vt.handoff=7
  PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
  RelatedPackageVersions:
   linux-restricted-modules-3.11.0-12-generic N/A
   linux-backports-modules-3.11.0-12-generic  N/A
   linux-firmware                             1.116
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/11/2012
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A14
  dmi.board.name: 0J4TFW
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A01
  dmi.chassis.type: 9
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA14:bd07/11/2012:svnDellInc.:pnLatitudeE6520:pvr01:rvnDellInc.:rn0J4TFW:rvrA01:cvnDellInc.:ct9:cvr:
  dmi.product.name: Latitude E6520
  dmi.product.version: 01
  dmi.sys.vendor: Dell Inc.

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