Power consumption double compared to windows... where could energy be

rggjan · 2011-11-27 21:05:07

I just bought a new Laptop (Acer Aspire 5755g), and first thing after I got it was, of course, installing arch ;-)

However, I noticed that the energy consumption under Linux is at least about 22 Watts in idle mode, while it uses only 10 Watts on the preinstalled Windows 7. I was wondering where the big power leak could be. That's what I already thought of:

• I enabled most of the laptop-mode energy saving options, that means ondemand CPU governor, soundcard/ethernet/wireless powersavings, usb autosuspend, hard drive power saving etc...
• Since it is a nvidia optimus laptop, it has two graphics cards. However, I disabled the nvidia graphics card in the BIOS (what saved about 5 Watts), and I think the remaining "cheap" intel chip should not use that much power.
• The laptop has an LCD LED display that can be quite bright. However, the 22 Watts are measured when background light is almost at the minimum.

Are there any ideas, where else the problem could be?

I know of the kernel power regression discussed on phoronix recently, but can this really double the power consumption?

rggjan · 2011-11-27 21:13:07

Ok, I just added "pcie_aspm=force" to grub, as mentioned here:

http://www.phoronix.com/scan.php?page=a … aspm&num=1

And power consumption actually dropped to about 19 Watts. However, that's still quite high, I think...

jon · 2011-11-28 00:18:49

I assume you are unplugging your laptop when you measure the power consumption, because as I recall laptop-mode-tools only activates on battery.

Have you tried running powertop (on battery power)? Any suggestions or high wakeups there?

rggjan · 2011-11-29 19:25:13

Yes, that was measured unplugged. However, this does not really matter since I have all the laptop-mode settings also enabled when on battery.

Have run both powertop and powertop2, and enabled the few things left there. Nothing with particularly high Events left there, highest thing is the tick_sched_timer.

With WLAN disabled, background light to the minimum and no programs running, I get down to 16 Watts. Still, thats 50% more than on windows, where I had more background light and WLAN enabled...

ancient_archer · 2011-11-29 21:11:02

It may be connected with the new 3.x kernel which has according to some sources up to 30% more energy consumption. So I would suggest installing older kernel: kernel26-lts + optionally kernel26-lts-headers.

Last edited by ancient_archer (2011-11-29 21:11:19)

Larsson · 2011-11-29 22:27:59

Don't want to highjack your thread, but can I ask how you measure the power consumption?

Awebb · 2011-11-29 22:37:35

Powertop, as mentioned before.

cybertorture · 2011-11-29 23:20:54

its funny that powertop give me less than 2w on t2300e witch is out of the question
anyway about your problem did you try "cpupower" as introduced in kernel 3.1
source

skunktrader · 2011-11-29 23:41:25

cybertorture wrote:

its funny that powertop give me less than 2w on t2300e witch is out of the question
anyway about your problem did you try "cpupower" as introduced in kernel 3.1
source

powertop has a bug with current kernel releases which makes its power calculation off by a factor of 10
https://bbs.archlinux.org/viewtopic.php?id=130149

rggjan · 2011-12-03 11:40:51

Actually, I measured the power consumption using the gnome-power-statistics tool, since both powertop's give wrong values.

As for the kernel26: I tried to boot into it, but during startup there was some sort of kernel panic or something. Not sure what the problem was, but this kernel doesn't seem to work for me... maybe some drivers missing or so.

rggjan · 2011-12-04 11:59:21

I just brought it down to under 8 Watts! Using this trick:

http://www.phoronix.com/scan.php?page=a … ower&num=1

What made the laptop finally turn of the fans, and really saves a lot of power...

jmissao · 2011-12-04 23:21:17

rggjan wrote:

I just brought it down to under 8 Watts! Using this trick:
http://www.phoronix.com/scan.php?page=a … ower&num=1
What made the laptop finally turn of the fans, and really saves a lot of power...

Indeed, this and the pcie_aspm option, plus disabling the NVidia card with power management from Bumblebee (extra dangerous BTW, I would not recomend, though I use it) and unloading some modules, took my Alienware M11xR3 consumption down to 7.95W.

graysky · 2011-12-04 23:49:01

I have an nvidia card in my laptop. I'll try the "pcie_aspm=force" kernel option. Beyond that, none of the tweaks in the linked article will apply to my system. I run gnome3 on it. Any suggestions to reduce power consumption?

Arch Linux

#1 2011-11-27 21:05:07

Power consumption double compared to windows... where could energy be

#2 2011-11-27 21:13:07

Re: Power consumption double compared to windows... where could energy be

#3 2011-11-28 00:18:49

Re: Power consumption double compared to windows... where could energy be

#4 2011-11-29 19:25:13

Re: Power consumption double compared to windows... where could energy be

#5 2011-11-29 21:11:02

Re: Power consumption double compared to windows... where could energy be

#6 2011-11-29 22:27:59

Re: Power consumption double compared to windows... where could energy be

#7 2011-11-29 22:37:35

Re: Power consumption double compared to windows... where could energy be

#8 2011-11-29 23:20:54

Re: Power consumption double compared to windows... where could energy be

#9 2011-11-29 23:41:25

Re: Power consumption double compared to windows... where could energy be

#10 2011-12-03 11:40:51

Re: Power consumption double compared to windows... where could energy be

#11 2011-12-04 11:59:21

Re: Power consumption double compared to windows... where could energy be

#12 2011-12-04 23:21:17

Re: Power consumption double compared to windows... where could energy be

#13 2011-12-04 23:49:01

Re: Power consumption double compared to windows... where could energy be

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