ATI fan controller

ati_fan_watch.rb

#!/usr/bin/env ruby

# Quick and dirty ATI fan control script.  This script will attempt to keep your
# cards around the OPTIMAL temperature within WINDOW degrees.  You'll probably
# need to run this as root.

OPTIMAL = 75 # Celcius
WINDOW  = 1  # Celcius
MIN_FAN = 40 # Minimum fan speed

def system_capture(cmd, raise_on_error = true)
  handle = IO.popen(cmd + " 2>&1")
  exit_code = Process.waitpid2(handle.pid)[1] >> 8
  output = handle.read

  if exit_code.to_i > 0 and raise_on_error
    raise "Command: #{cmd} exited with code: #{exit_code}, output follows:\n#{output}"
  end

  return [exit_code, output]
end

while true do
  # Get current temps
  code, temps = system_capture('aticonfig --odgt --adapter=all')

  temps.gsub("\n", '').scan(/Adapter (\d+).*? (\d+\.\d+) C/).each do |card, temp|
    # Get current fan for this card
    code, fan = system_capture("DISPLAY=:0.#{card} aticonfig --pplib-cmd 'get fanspeed 0'")
    fan = fan.match(/Speed: (\d+)/)[1]

    puts "Card #{card} current: temp #{temp}C, fan #{fan}%"

    temp = temp.to_i
    fan  = fan.to_i

    next if (OPTIMAL - temp).abs <= WINDOW


    if OPTIMAL > temp
      next if fan <= MIN_FAN
      puts "\tDecreasing fan"
      code, output = system_capture("DISPLAY=:0.#{card} aticonfig --pplib-cmd 'set fanspeed 0 #{fan - 1}'")
      raise "unable to decrease fan to #{new_fan} on card #{card}" if code != 0
    else
      puts "\tIncreasing fan"
      code, output = system_capture("DISPLAY=:0.#{card} aticonfig --pplib-cmd 'set fanspeed 0 #{fan + 1}'")
      raise "unable to increase fan to #{new_fan} on card #{card}" if code != 0
    end
  end

  sleep 5
end