Power Saving

Increase dirty writeback

Note this may lead to data loss up to 60 seconds. We have already adapted the commit time in /etc/fstab earlier.

Create /etc/sysctl.d/dirty.conf with content:

vm.dirty_writeback_centisecs = 6000

You may want to run mkinitcpio -P afterwards.

Enable WiFi power-save

Create /etc/modprobe.d/iwlwifi.conf with content:

options iwlwifi power_save=1

You may want to run mkinitcpio -P afterwards.

Activate PCI Runtime Power Management

Create /etc/udev/rules.d/pci_pm.rules with content:

SUBSYSTEM=="pci", ATTR{power/control}="auto"
SUBSYSTEM=="ata_port", KERNEL=="ata*", ATTR{device/power/control}="auto"

You may want to run mkinitcpio -P afterwards.

Activate USB power saving

Create /etc/udev/rules.d/50-usb_power_save.rules with content:

# blacklist for usb autosuspend
# ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="05c6", ATTR{idProduct}=="9205", GOTO="power_usb_rules_end"

# CHERRY G83 (RS 6000) Keyboard
ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="046a", ATTR{idProduct}=="0011", GOTO="power_usb_rules_end"

# Dell Computer Corp. Dell MS116 Optical Mouse
ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="413c", ATTR{idProduct}=="301a", GOTO="power_usb_rules_end"

ACTION=="add", SUBSYSTEM=="usb", TEST=="power/control", ATTR{power/control}="auto"
LABEL="power_usb_rules_end"

Note that the blacklist can be used in case you encounter a device which has problems with that. You may want to run mkinitcpio -P afterwards.

Setup some services to run only on AC power

This requires some preparation, as it is not a built-in feature to systemd or udev.

Create the file /etc/systemd/system/battery-power.target with content:

[Unit]
Description=Battery-only services

and the file /etc/systemd/system/ac-power.target with content:

[Unit]
Description=AC-only services

Then, hook that unit udev by creating /etc/udev/rules.d/99-powertargets.rules with content:

SUBSYSTEM=="power_supply", KERNEL=="AC", ATTR{online}=="0", RUN+="/usr/bin/sh -c '/usr/sbin/systemctl stop ac-power.target && /usr/sbin/systemctl start battery-power.target'"
SUBSYSTEM=="power_supply", KERNEL=="AC", ATTR{online}=="1", RUN+="/usr/bin/sh -c '/usr/sbin/systemctl stop battery-power.target && /usr/sbin/systemctl start ac-power.target'"

and finally reload everything as-needed:

systemctl daemon-reload
udevadm control --reload-rules
udevadm trigger

Now, set up services as wanted, for example, you’ll likely want to do this for beesd (see also BEES (for btrfs dedupe)):

mkdir -p /etc/systemd/system/beesd\@.service.d/

In there, create /etc/systemd/system/beesd\@.service.d/only-on-ac.conf with content:

[Unit]
PartOf=ac-power.target

[Install]
WantedBy=ac-power.target

To activate the Install part, you need to re-enable the service after reloading systemd, for example:

systemctl daemon-reload
systemctl enable beesd@b8a34ebc-029a-4c77-ac2c-33290c18b461.service

Now, the service should be switched with AC state. You can check like this:

systemctl status ac-power.target
systemctl status battery-power.target

and of course by investigating the logs of affected services.

Intel Low-Power-Mode Daemon

Install service:

yay -S intel-lpmd

Enable it:

systemctl enable --now intel_lpmd

Still need to determine whether that helps (may need to set intel_lpmd_control AUTO or write an actual XML config).

Check in:

systemctl status intel-lpmd

then copy over config to more matching config, e.g.:

cp /etc/intel_lpmd/intel_lpmd_config_F6_M189.xml /etc/intel_lpmd/intel_lpmd_config_F6_M189_T17.xml

and edit to your liking, for example:

<PerformanceDef>-1</PerformanceDef>
<BalancedDef>0</BalancedDef>
<PowersaverDef>1</PowersaverDef>

Note: Switching to powersave with this example config means only the E cores will be used. In case performance is not required, this can increase battery runtime noticeably.