Optimising power consumption of backlight and wifi

orschiro · 2014-04-08 14:09:47

Hi there,

Do you have any effective measures in place to optimise power consumption of backlight and wifi?

On my Thinkpad X200T they are by far the biggest consumers of power.

How much does backlight and wifi consume on your laptops?

centos · 2014-05-02 12:53:26

Hi,
I also have troubles with backlight. Changing kernel parameters hasn't helped, currently I have acpi_osi='!Windows 2012' acpi_backlight=legacy but it seems to be no change from others ("acpi_osi=Linux acpi_backlight=vendor", "acpi_osi='!Windows 2012' acpi_osi=Linux" or no parameter specified).
My laptop is Thinkpad Edge E430. Even with powerdown script I only get 3 hours of web browsing and I don't know what to do about it.

orschiro · 2014-05-02 17:01:49

@centos

Is the consumption shown in your screenshot at minimum brightness?

centos · 2014-05-03 15:36:28

As I remember it was the third darkest step (brightness key up). Now I have it at minimum brightness and I get 6.13 W and 5 %. But it is too dark to use in daylight, I would say it is usable only in the night with no lights on, so I use two more brightness steps up as in the screenshot.

edit: and minimum brightness is

% cat /sys/class/backlight/intel_backlight/actual_brightness 
244

Last edited by centos (2014-05-03 15:38:44)

orschiro · 2014-05-03 18:13:29

@centos

The 6.13 W is for the display, right?

Since you are already using the finer grained intel_backlight, I guess there is really not much to do.

centos · 2014-05-04 16:10:30

Yes, it's brightness only, in total I get more than 10 W, which is terrible.
But to be honest I don't know what that percentage in second column means.

orschiro · 2014-05-05 06:28:43

If you go to the Device stats tab, you see that the % column is labelled Usage.

However, neither do I know what it precisely means.

Out of curiousity, is Display Backlight displayed twice for you under Device Stats?

Last edited by orschiro (2014-05-05 06:30:23)

centos · 2014-05-09 13:54:03

I just did system update and powertop is acting kinda weird. I get about 7 W CPU (which is almost not used) and nothing for backlight (which I see only once btw). I'll try again later if I'll get some reasonable numbers.

orschiro · 2014-05-11 12:08:45

Do you have powertop or powertop-git installed? Do the results change between the two?

amaro · 2014-05-12 15:55:26

I usually get 15 W and approximately 2 1/2 hours on hp 6910p (Korora 20) and this is the best I could get. I checked that

centos wrote:

% cat /sys/class/backlight/intel_backlight/actual_brightness 
244

and it looks very differently

 cat /sys/class/backlight/intel_backlight/actual_brightness 
110080

I tried

 echo 1 > /sys/class/backlight/intel_backlight/brightness 
1

and it worked and gave 13.5 W and approximately 3 hours but upon reboot had to do it again. Tried to put it in rc.local and in .xsession and nothing happens. Needs to be manually added on every reboot. Noticed that it's very good for my eyes, there is a big difference.

centos · 2014-05-12 19:09:43

amaro: Try changing the boot parameter (my first post).
orschiro: powertop. I'll try the other one and let you know.

amaro · 2014-05-13 09:00:54

@centos
Well, I tried acpi_osi='!Windows 2012' acpi_backlight=legacy and got 11.9 W and 4 hours which is a record
Interestingly when the results were 13.5 W and 15 W powertop showed

7.66 W     33.7%                      Device         Display backlight

Now it shows

11.0 W     76.8%                      Device         Display backlight

@orschiro
And I also have it twice

orschiro wrote:

If you go to the Device stats tab, you see that the % column is labelled Usage.
Out of curiousity, is Display Backlight displayed twice for you under Device Stats?

With acpi_osi='!Windows 2012' acpi_backlight=legacy and 11.9 W and 4 hours

5.52 W 	76.8% 	Display backlight
5.52 W 	20.0% 	Display backlight

Without acpi_osi='!Windows 2012' acpi_backlight=legacy and 13.5 W and approximately 3 hours

3.83 W 	33.7% 	Display backlight
3.83 W 	20.0% 	Display backlight

centos · 2014-05-17 13:55:55

@amaro: Glad it helped

@orschiro: Now I have the git version and it's the same. I get about 8 Watts for usb mouse and nothing for backlight. Measurement is broken, I believe it is caused by changes in upower API.

orschiro · 2014-05-21 05:12:03

@centos

Regarding pure measurement, you can also try powerstat from the AUR.

Arch Linux

#1 2014-04-08 14:09:47

Optimising power consumption of backlight and wifi

#2 2014-05-02 12:53:26

Re: Optimising power consumption of backlight and wifi

#3 2014-05-02 17:01:49

Re: Optimising power consumption of backlight and wifi

#4 2014-05-03 15:36:28

Re: Optimising power consumption of backlight and wifi

#5 2014-05-03 18:13:29

Re: Optimising power consumption of backlight and wifi

#6 2014-05-04 16:10:30

Re: Optimising power consumption of backlight and wifi

#7 2014-05-05 06:28:43

Re: Optimising power consumption of backlight and wifi

#8 2014-05-09 13:54:03

Re: Optimising power consumption of backlight and wifi

#9 2014-05-11 12:08:45

Re: Optimising power consumption of backlight and wifi

#10 2014-05-12 15:55:26

Re: Optimising power consumption of backlight and wifi

#11 2014-05-12 19:09:43

Re: Optimising power consumption of backlight and wifi

#12 2014-05-13 09:00:54

Re: Optimising power consumption of backlight and wifi

#13 2014-05-17 13:55:55

Re: Optimising power consumption of backlight and wifi

#14 2014-05-21 05:12:03

Re: Optimising power consumption of backlight and wifi

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