[ltp] High power consumption after suspend/resume cycle

[Robert Tomsick]

On Wed, 2009-10-07 at 11:51 +0200, Volker Krueger wrote:

> Presently, all I can do on my X200s to get it below 9W is to switch it
> off :-)

I have an X200s (1440x900 screen) and I'm able to get it to idle at ~7W
with 2.6.28.10.  I was able to get it as low as 5.4W using a newer
kernel and a less "chatty" userland, but since I like to run a mostly
standard install, my average idle usage is around 7W.  That's about 2W
more than with a properly-tuned Windows install, but since 7W gives me
about 7 hours on the six cell battery, I'm content.

Here are some things to try:

1) Use the 'intel' driver in UXA mode.  If UXA isn't an option, disable
DRI (older versions of the intel driver generate several interrupts
every second when DRI is enabled.)

2) Build a custom kernel and apply the patch to power off unused SATA
ports.

3) Check to make sure that xrandr has disabled HDMI-1 and HDMI-2 (along
with other unused outputs.)

4) Make sure your wireless card is in powersaving mode.

5) Force your Ethernet card into 100mbit mode and disable WOL (or unload
e1000e entirely if you're not using it.)

6) Disable all unused devices via the BIOS.  Take extra care to make
sure the fingerprint reader is disabled, as that will keep USB awake
otherwise.  Disable Bluetooth if at all possible (it's also rather
power-hungry.)

7) Make sure that processor freq. scaling and USB sleep are not disabled
in the BIOS.  They shouldn't be, but it's worth checking,

8) Enable USB autosuspend (via the kernel param that powertop suggests.)

That brings me to...

9) Follow powertop's suggestions.  Add the recommended commands
to /etc/acpi/battery.d/99-custom.sh or somesuch, and take out and shoot
all the misbehaving programs that it finds.

10) If you're building a custom kernel, enable Intel HDA sleep and set
the sleep timeout to 1 second.  Otherwise, add the appropriate sysctl
manipulation (available on ThinkWiki) to your battery ACPI script.

ThinkWiki's got a bunch of good general ThinkPad-related powersaving
tips, but the above were some of the ones that were most useful for me.

Hope that's of use to someone.

Oh, and one more thing: some of the X200s models have an SU9300/SU9400,
whereas others have an SL9x00 -- there is a notable difference in power
consumption, as the former are ULV chips and the latter are merely LV
chips.  From what I've seen the ULV models are/were only common in the
US.  That might explain some of the difference with regards to power
consumption.

-Rob