Tweaks To Extend The Battery Life Of Intel Linux Notebooks

[TechMage89]

As /etc/default/grub is referenced by the GRUB manual, I must assume that distros that don't use it are the "outsiders".

That's the manual for GRUB2, which is pretty significantly different from GRUB, which is what many of us are still running.

[Max Spain]

Thank you for the article, but I would have liked to have seen how using these power saving options compares to using previous versions of the kernel. If it reduces power to the same level as earlier versions then there would be no reason to avoid upgrading kernels.

[grigi]

ok, Back to the topic!

I tested all those options on an Acer Aspire One Happy (Atom N450, 2GB ram), using Kernel 3.0.1

i915.i915_enable_rc6=1
No effect at all. I suspect this is only for the Core i series of processors.

pcie_aspm=force
No effect. I think no peripherals are connected using the PCIe bus.

i915.i915_enable_fbc=1
Works. Actually improved performance a bit.

i915.lvds_downclock=1
Works quite well, probably because of the low resolution screen? (1024x600)

The last 2 options together, saved me about 10% power consumption in pure idle, and it seems to carry over on a lightly loaded system.
So, ATOM users are not completely left out to dry with these options either :-)

[tball]

Does this only works with newer kernels? or is it only driver dependent?
Would this work with Debian stable?

[grigi]

i915.i915_enable_fbc=1
Has been around for a very long while. Intel driver specific.
i915.lvds_downclock=1
Has been around for a very long while. Intel driver specific. Only works on systems that has lvds displays (typically notebooks only)

915.i915_enable_rc6=1
Is new, and very gpu specific. Intel Core i<somethingmeaningless>

pcie_aspm=force
Is only needed from 2.6.38 onwards, but works on any system.

[lkraav]

i'm running an Arrandale Acer Travelmate 8172T i3-330UM laptop.

i have been wondering if there's a way to influence fan trippoints on this machine. my regular idling temperatures with no tweaks have been 45/37 for two cores, that's when machine is dead quiet and just how i like it. but as soon as temperature crosses 47C, and that's pretty much with doing anything that changes anything on the screen, audible fan comes immediately on. so far i haven't found a way to do anything about it, haven't had the time either to learn more about modifying DSDT, to see if that's an option here at all. hints welcome btw.

back to topic. enabled all three options (+ pcie_aspm=force) and first apparent effect is that my idle temps rose by about 7C. even with machine sitting totally idle, temps would hover around 53-54C, instead of the earlier 46+.

now i only have pcie_aspm=force + i915_enable_rc6=1. idle temps seem to hover around 50C now, will have to do further monitoring, whether they will drop down to previous levels when the machine is completely idle instead of me typing in this firefox javascripted forum.

$ uname -a
Linux travelmate 3.0.2-pf #4 SMP PREEMPT Fri Aug 26 12:39:19 EEST 2011 i686 Intel(R) Core(TM) i3 CPU U 330 @ 1.20GHz GenuineIntel GNU/Linux

$ sudo grep -H '' /sys/module/i915/parameters/*
/sys/module/i915/parameters/fbpercrtc:0
/sys/module/i915/parameters/i915_enable_fbc:0
/sys/module/i915/parameters/i915_enable_rc6:1
/sys/module/i915/parameters/lvds_downclock:0
/sys/module/i915/parameters/lvds_use_ssc:1
/sys/module/i915/parameters/modeset:-1
/sys/module/i915/parameters/panel_ignore_lid:0
/sys/module/i915/parameters/powersave:1
/sys/module/i915/parameters/reset:Y
/sys/module/i915/parameters/semaphores:0
/sys/module/i915/parameters/vbt_sdvo_panel_type:-1

there's another parameter - powersave. does that have anything to do with anything here?

$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1:         +6.8°C  (crit = +100.0°C)
temp2:         +5.8°C  (crit = +119.8°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0:       +44.0°C  (high = +95.0°C, crit = +105.0°C)
Core 2:       +50.0°C  (high = +95.0°C, crit = +105.0°C)

i have no idea what the acpitz temperatures are. https://bugzilla.kernel.org/show_bug.cgi?id=41612 hints welcome.

so far it seems on this laptop these tweaks have an opposite effect on power consumption.

[dimitris]

I'm running 64-bit Lucid on a Thinkpad X200s. When at "home base" this in a dual head configuration: X200 UltraBase/DisplayPort-to-DVI-D adapter/Dell 20-inch 1600x1200 panel. I tried the enable_fbc and lvds_downclock options.

enable_fbc does not seem to be supported by the i915 version in Lucid:

parm:           modeset:int
parm:           fbpercrtc:int
parm:           powersave:int
parm:           lvds_downclock:int

and adding it to /etc/modprobe.d/foo.conf options led to the module not loading, which in turn broke both displays: wrong resolution on both plymouth and gdm. In fact I could not see gdm. Not sure if it was not there at all or "displayed" with an offset that made it not visible on the screen.

Enabling only lvds_downclock still resuts in major problems with my system: Again, plymouth looks wrong (including barely visible cryptsetup prompt) and gdm is not shown. Furthermore, now attempting to ctrl-alt-F1 to get to a console results in a corrupt "rainbow" pattern on the bottom left of both screens, or just the laptop panel if the machine is booted with the Dell display switched off, instead of the console.