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[korAk <1289961@xxxxxxxxxxxxxxxxxx>]

I can confirm this bug. I've got a Lenovo Yoga 2 Pro.

Ubuntu 12.04.4
3.11.0-15-generic
iwlwifi
firmware 22.0.7.0
power management enabled: 90 Mbps (that is my max possible internet speed, haven't tried any local file transfers tough maybe it is even faster)
power management disabled: 90 Mbps
--> PM does not seem to have an effect on the wifi speed but the connection isn't stable at all. It reconnect aproximately ever 2 minutes.

Ubuntu 14.04
3.13.0.-17-generic
iwlwifi
firmware 22.24.8.0
power management enabled: 4-24 Mbps (<- signal strength changes)
power management disabled: 32 Mbps (<- signal strength seems to be always good)
--> Here I don't have any disconnects and PM has an influence but additionally the speed is generally a lot slower.

3.14.0-031400rc6-generic
firmware 22.24.8.0
--> I cannot notice different behavior compared to previous kernel, at least no noteworthy differences

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https://bugs.launchpad.net/bugs/1289961

Title:
  Power management causes Intel wifi 7260 slowness

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I get a new ThinkPad T440s with Intel 7260 ac wireless.

  The dowload speed reachs an upper limit 400 kB/s instead of the normal
  1500 kB/s I get with some other PC connected to my network. The speed
  often slows down very very low, especially when I'm far away from my
  AP.

  I use Ubuntu Trusty (Gnome) up-to-date.

  Removing N mode does not solve the issue. So I tried removing the
  wireless interface's power management in Powertop and it did solve the
  slowness issue. (iwconfig shows "Power management : off" in this case,
  obviously.)


  lspci************************

  03:00.0 Network controller: Intel Corporation Wireless 7260 (rev 83)

  lshw*************************

  *-network
                  description: Interface réseau sans fil
                  produit: Wireless 7260
                  fabriquant: Intel Corporation
                  identifiant matériel: 0
                  information bus: pci@0000:03:00.0
                  nom logique: wlan0
                  version: 83
                  numéro de série: xxxxxxxxxxx
                  bits: 64 bits
                  horloge: 33MHz
                  fonctionnalités: bus_master cap_list ethernet physical wireless
                  configuration: broadcast=yes driver=iwlwifi driverversion=3.13.0-16-generic firmware=22.24.8.0 ip=192.168.1.21 latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn
                  ressources: irq:61 mémoire:f0400000-f0401fff

  iwconfig*******************************

  wlan0     IEEE 802.11abgn  ESSID:"Livebox"  
            Mode:Managed  Frequency:2.437 GHz  Access Point: xxx   
            Bit Rate=130 Mb/s   Tx-Power=16 dBm   
            Retry  long limit:7   RTS thr:off   Fragment thr:off
            Power Management:on
            Link Quality=60/70  Signal level=-50 dBm  
            Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
            Tx excessive retries:2549  Invalid misc:273   Missed beacon:0

  ifconfig******************************

  wlan0     Link encap:Ethernet  HWaddr xxx
            inet adr:192.168.1.21  Bcast:192.168.1.255  Masque:255.255.255.0
            adr inet6:xxx/64 Scope:Lien
            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
            Packets reçus:30450 erreurs:0 :0 overruns:0 frame:0
            TX packets:18296 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 lg file transmission:1000 
            Octets reçus:41761779 (41.7 MB) Octets transmis:1992389 (1.9 MB)

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