Powersave

This is a powersaving script for Linux. Initially, I've created it for my own laptop. That means that this script will not work on every setup so please check this before running it on your computer! Things might break otherwise and I will not be responsible for any damage that has been done. This script gives me roughly 1:30/2:00 hours of battery life, on a battery that would otherwise last ~45 minutes. (yea, I know, my battery is fried)

Installation

The script will need the following dependencies to run:

• hdparm
• wireless_tools
• xset
• udev
• udisks

Just run make install as root to install the script and the udev rules.

Usage

Once the script is installed, one can run powersave true | false and the powersaving will kick in. The udev rule will automatically run these commands depending on the battery state (Charging, discharging). The other udev rule will also enable or disable CD polling by udisks, depending on the battery state.

Configuration

Things you should edit, should you use this on your setup:

• NMI watchdog; I have this disabled at kernel level. If you don't, then uncomment the line in the powersave script. This option is safe to do! Should you want to disable this at kernel level too, use: nmi_watchdog=0
• ASPM powersave; this option is safe! To be able to write to this file you have to use a kernel parameter at boot: pcie_aspm=force
• Disk powersave; as I have only one HDD (laptop), I have edited the wildcard that Taylorchu originally uses. If you have multiple HDD's and want to run powersave on all of them, then use this: for dev in $(awk '/^\/dev\/sd/ {print $1}' /etc/mtab); do hdparm -S 6 -B 254 -a 2048 $dev; done
  Also, note that I use -B254. I hate the clicking noises my HDD would make otherwise, but this is not power-efficient. If you want maximum powersave, use -B1. THIS CAN HURT YOUR HARDDRIVE, SO BE CAREFUL.
• Screen powersave; this option is safe! The numbers of brightness differ per manufacturer. You should check yours. Do so by setting your screen on maximum brightness and then running cat/sys/class/backlight/acpi_video*/brightness Then, lookup the false) part in the script and change the value. Mine is set to 9.
• Battery line in the systemd sleep hook, your setup might have a different path.

These modules can be blacklisted to save power:

• btusb
• bluetooth
• uhci_hcd
• pcmcia
• yenta_socket
• ipw2200
• ohci1394
• firewire-ohci

In Arch Linux, add this list to /etc/modprobe.d/blacklist.conf to have them all blacklisted at boot.

ToDo

• Set more aggresive power savings