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When I run Powertop, and look at the Tunables screen, about twenty things are listed as Bad. I can toggle these to Good by pressing enter, and when I do so, projected battery lifetime doubles.

How can I make these changes persist? (I'm on Fedora 18, by the way, with Powertop 2.2)

mattdm
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3 Answers3

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Powertop is not a permanent tool, as you know, so you will have to setup your system to run the commands through sysctl, udev, systemd units, scripts, whatever...

In order to see what commands are used by powertop you will have to run powertop --html BEFORE MAKING ANY CHANGES, that is, BEFORE toggling the settings from Bad to Good. If you already tuned for maximum battery life, undo your changes and run powertop --html again.

This is what the output should look like:

enter image description here

don_crissti
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    AH! The part in all caps is exactly what I was missing. – mattdm Feb 24 '13 at 16:44
  • Excitingly, some of the advice appears to be _backwards_. For example, it says `iw dev wlan0 set power_save off`, but turning it _on_ is what changes the setting to "Good". – mattdm Feb 24 '13 at 16:45
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When following all powertop suggestions you can also call it with the --auto-tune option:

   --auto-tune
         Set all tunable options to their good setting without interaction.

Thus, calling powertop --auto-tune from a start script would make it permanent (e.g. from rc.local).

maxschlepzig
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  • There may be particular settings e.g. USB device sleep that you might want to disable from auto-tuning. It'd be nice to have a way to do that. – jocull Jan 30 '19 at 18:22
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Look into /etc/rc.local. powertop suggests some commands to run , so insert them there.

schaiba
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    I have no `/etc/rc.conf`. Also, powertop doesn't seem to be suggesting any commands to run. (I think it did that in an older version.) – mattdm Feb 24 '13 at 15:07
  • Create it if it isn't there. Use powertop --html and open the resulting file, going to the section called 'Software Settings in need of Tuning' – schaiba Feb 24 '13 at 15:12
  • If I create that file, I'm quite sure it will do nothing on my system. And the html output has no section by that name. There is _Optimal Tuned Software Settings_, but that just lists items like "Enable SATA link power Managmenet for host0", with no commands. – mattdm Feb 24 '13 at 15:19
  • My bad, that was meant to be rc.local. Fedora has , IIRC, a systemd unit file that will run that. – schaiba Feb 24 '13 at 15:23
  • Thanks, yeah, that would work. However, the key problem still stands: `powertop --html` (or anything else I can see) still doesn't tell me any actual commands. I assume they're mostly kernel tunables, so they really should go in `/etc/sysctl.conf` or under `/etc/sysctl.d/`, but I'm not sure what should be set (or to what values). – mattdm Feb 24 '13 at 15:29
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    I'm not on Fedora, I'm on Arch, and not only I have that section, but I do have the suggested commands. Perhaps anyone using Fedora could help further. – schaiba Feb 24 '13 at 15:31
  • Adding some information as I came accross this question : Arch initscripts are handled by `systemd`, see the wiki for more details : https://wiki.archlinux.org/index.php/Initscripts‎ – John WH Smith Sep 09 '13 at 22:11