Call For Testing: pm-utils-powersave-policy

Chase Douglas chase.douglas at
Thu Mar 18 14:59:58 GMT 2010

Hello all,

I've been working on some fixes, additions, and cleanup to the current
pm-utils-powersave-policy package that's slated for inclusion in
Lucid. The package takes some of the good stuff from the old
laptop-mode-tools package and moves it to policy scripts that are
invoked by pm-powersave when on battery power. The items currently

* 10 second audio codec power down (vs no power down)
* 1 minute console (tty1) screen powersave timeout
* 60 (vs 15) second dirty page writeback timeout
* Disable WOL for ethernet devices
* Enable SATA link power save mode (when swapping is unlikely)
* Enable multi-thread and multi-core power save mode

To test these changes, please add my powersave ppa
(ppa:chasedouglas/powersave) and upgrade the pm-utils and
pm-utils-powersave-policy packages. When you transition from AC to
battery power these scripts will fire and log what they did (if
anything) to /var/log/pm-powersave.log. You can also test by running
'sudo pm-powersave true' to enable power saving, or 'sudo pm-powersave
false' to disable power saving.

One easy way to gauge power savings is to install powertop and execute
while on battery power:

$ sudo sh -c "sleep 30; powertop -d -t 30"

This will wait 30 seconds and then retrieve power information for 30
seconds. During this time you should not use your laptop as we are
trying to get a steady-state result. It wouldn't hurt to run this a
few times to ensure the results are consistent. In the output you
should find a "Power usage (ACPI estimate)" wattage that describes how
much energy is used by the system.

I am interested in hearing whether the scripts seem to be doing their
job by looking at the pm-powersave.log file and the power usage. A
comparison to Karmic power usage would also be helpful, but not


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