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Author Topic: Does removing modules save power?  (Read 1186 times)
wcs
Packager
Vectorian
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Posts: 1144


« on: March 11, 2009, 08:17:10 am »

Some netbooks come with a way to switch wireless off, which is claimed to save power.
Unfortunately, with the VL6 kernel, the "wifi kill switch" on my aspire one is a bit moody, and works when it feels like it.

Another thing I'd like to turn off when not using is the webcam. Ubuntu docs suggest that this is handled by the files "level" and "autosuspend" inside /sys/bus/usb/devices/1-5/power/, but I have no such files associated with the webcam device.

So the question is in the title. Do you reckon any power gets saved by removing the wireless and webcam kernel modules from the kernel and loading them when I need to?

Or do I need to go to a lower-level to make sure that these devices are "off off".

Thank you!
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M0E-lnx
Administrator
Vectorian
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Posts: 3134



« Reply #1 on: March 11, 2009, 09:56:42 am »

I guess the technical question would be yes... but then there is the question of "how much power is saved?"

think about it... take for instance the wifi interface...
So you turn that off... which powers off the LED behind your indicator...
How much power does that LED really consume?...
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lagagnon
Global Moderator
Vectorian
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Posts: 1922



WWW
« Reply #2 on: March 11, 2009, 10:28:28 am »

The chip that does the wifi transmit is what really consumes power. I think that needs to be hardware turned off, I am unsure of whether just removing the module would do that - I doubt it. Same goes for the webcam. You would need to do that with a hardware switch of some sort to notice any major power saving. As far a I know the biggest watt consumers on laptops/netbooks, in order are:

1) screen - so turn down brightness, turn off screen when unused.
2) CPU - use power saving apps for CPU and don't run 100% CPU apps such as games, etc.
3) optical drives and hard drives (if present)
4) wireless transmitter
5) webcam device

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"As people become more intelligent they care less for preachers and more for teachers". Robert G. Ingersoll
AMAMH
Member
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Posts: 6


« Reply #3 on: March 27, 2009, 03:02:25 am »

why do u think that the switch doesn't turn off the wifi
when I use the switch I can't find any wireless network with wicd, when I use it again I can see wireless networks again, doesn't that mean it works?
for the webcam, I don't know

btw the lowest battery consumption that I can reach is about 890 mA (displayed in the "System profiler and benchmarker" app that comes pre-installed)
here is how I get that:
use VL-HOT as default mounter, choose that from VASM
disable all services on runlevel 4 desktop (except wicd if it exists)
restart and just after vector linux starts :-
open vcpufreq and set powersave and  set max freq to 800, check save on exit
open htop and make sure no process is using the cpu heavily
use lowest brightness
turn off wifi with the switch (check wicd to make sure it's turned off)

now open system profiler and benchmarker and choose battery to see power consumption I think it should be < 900 mA

I don't have my laptop right now to check those steps that I have typed those r from my mem, anyway consider them as some hints I don't like sequential instructions anyway

please report if it worked for u

have a nice day Smiley

ah, I forgot something, I think u should change thread's name to something like "power consumption on acer one"  or something like that.
« Last Edit: March 27, 2009, 03:09:34 am by AMAMH » Logged
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