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#1 2016-01-29 02:43:58

Vytautas
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Registered: 2016-01-17
Posts: 27

iwlwifi power usage: 3W vs 6W on same software and hardware

Hi,

I have two Lenovo x220 machines with Bunsenlabs on the same desk. They are both with Centrino Advanced-N 6205 wifi and connected to the same WEP2 router.

Power usage measured with powertop for Network interface: wlan0 (iwlwifi) on the first system is 6W and on the second is 3W.


iwconfig wlan0 info on both machines is the same:

wlan0     IEEE 802.11abgn  ESSID:"TEO"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: D0:D4:12:7E:AB:20   
          Bit Rate=144.4 Mb/s   Tx-Power=15 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=63/70  Signal level=-47 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:95   Missed beacon:0

Except that 3W system has additional line:

Encryption key: off

How can I find out the reasons for different power usage and have 3W on both machines?

Thank you in advance!
Vytautas

Last edited by Vytautas (2016-02-09 08:59:10)

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#2 2016-01-29 06:46:16

Head_on_a_Stick
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From: London
Registered: 2015-09-29
Posts: 8,759
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Re: iwlwifi power usage: 3W vs 6W on same software and hardware

How are you measuring the power consumption?


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#3 2016-01-29 11:09:56

twoion
ほやほや
Registered: 2015-08-10
Posts: 2,600

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

Vytautas wrote:

Hi,

I have two Lenovo x220 machines with Bunsenlabs on the same desk. They are both with Centrino Advanced-N 6205 wifi and connected to the same WEP2 router.

Measured power usage for Network interface: wlan0 (iwlwifi) on the first system is 6W and on the second is 3W.


iwconfig wlan0 info on both machines is the same:

wlan0     IEEE 802.11abgn  ESSID:"TEO"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: D0:D4:12:7E:AB:20   
          Bit Rate=144.4 Mb/s   Tx-Power=15 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=63/70  Signal level=-47 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:95   Missed beacon:0

Except that 3W system has additional line:

Encryption key: off

How can I find out the reasons for different power usage and have 3W on both machines?

Thank you in advance!
Vytautas

Use powertop, in particular the 'Device stats' and 'Tunables' sections.

apt-get install powertop

The show must go on.

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#4 2016-02-09 08:58:12

Vytautas
Member
Registered: 2016-01-17
Posts: 27

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

I have used powertop. Sorry for not mentioning that in the first post.

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#5 2016-02-09 09:45:39

Head_on_a_Stick
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From: London
Registered: 2015-09-29
Posts: 8,759
Website

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

Vytautas wrote:

I have used powertop

That is not an accurate measurement of power consumption and relies on accurate reporting of ACPI data from your hardware.

Try using an external power consumption analyser, I think you will find that the usage is pretty much equivalent wink


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#6 2016-02-10 11:13:28

Vytautas
Member
Registered: 2016-01-17
Posts: 27

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

What concerns me it is wlan power usage. It is high all the time. Wlan is the biggest power sucker on my notebook.

9.48 W      2.2 pkts/s  Network interface: wlan0 (iwlwifi)

and I have found that

sudo sh -c 'modprobe -rv iwlmvm && modprobe iwlwifi 11n_disable=0 power_save=1 power_level=5'

does not help. Link quality is high (63/70).

What else should I try? I know that I can just use wlan switch but I would like it to be done automaticaly by OS.

Last edited by Vytautas (2016-02-10 11:17:20)

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#7 2016-02-10 11:29:48

Head_on_a_Stick
Member
From: London
Registered: 2015-09-29
Posts: 8,759
Website

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

Vytautas wrote:
9.48 W      2.2 pkts/s  Network interface: wlan0 (iwlwifi)

yikes

I wrote:

That is not an accurate measurement of power consumption

I don't think your machine is sinking 10W into your wi-fi card.

Is the battery life noticeably shorter when compared to your other laptop?


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#8 2016-02-10 18:18:55

Vytautas
Member
Registered: 2016-01-17
Posts: 27

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

Yes, it should mistake. I tested hardware switch and it gave me ~30 min. additional time. My x220 with Bunsenlabs lasts for 4 hours with 6 cell battery, 90% charge.

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#9 2016-02-10 18:32:54

Head_on_a_Stick
Member
From: London
Registered: 2015-09-29
Posts: 8,759
Website

Re: iwlwifi power usage: 3W vs 6W on same software and hardware

Vytautas wrote:

I have two Lenovo x220 machines

How does the battery life compare between the two devices?

You say that the powertop readings are different but I would be inclined to blame this on slightly different ACPI implementations (eg, because of different firmware (BIOS) versions) rather than power consumption per se.


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