Script to run on udev power_supply events to adjust Macbook performance for battery/AC

powerchange

#!/bin/sh -e

# Executed by udev upon power supply status changes using this rule:
# SUBSYSTEM=="power_supply", RUN+="/usr/local/bin/powerchange"

# This script sets minimum performance on battery. Adjust to suit.
BATTERY_BRIGHTNESS=250
# AC brightness is the maximum level.

if [ $POWER_SUPPLY_ONLINE = 1 ]; then
  echo "Power supply online" | systemd-cat -t powerchange
  x86_energy_perf_policy performance
  for cpufreq in /sys/devices/system/cpu/cpu*/cpufreq ; do
    cat $cpufreq/cpuinfo_max_freq > $cpufreq/scaling_max_freq
  done
  echo 0 > /sys/devices/system/cpu/intel_pstate/no_turbo
  echo 100 > /sys/devices/system/cpu/intel_pstate/max_perf_pct
  # Change the brightness last. If it doesn't change, we know something above failed and can check the journal.
  cat /sys/class/backlight/gmux_backlight/max_brightness > /sys/class/backlight/gmux_backlight/brightness
else
  echo "Power supply offline" | systemd-cat -t powerchange
  x86_energy_perf_policy powersave
  for cpufreq in /sys/devices/system/cpu/cpu*/cpufreq ; do
    cat $cpufreq/scaling_min_freq > $cpufreq/scaling_max_freq
  done
  echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
  cat /sys/devices/system/cpu/intel_pstate/min_perf_pct > /sys/devices/system/cpu/intel_pstate/max_perf_pct
  # Change the brightness last. If it doesn't change, we know something above failed and can check the journal.
  echo $BATTERY_BRIGHTNESS > /sys/class/backlight/gmux_backlight/brightness
fi