=== Simple user tips for improving power usage ===
* Enforce turning of machines that are not used (e.g. company policy)
* Turn of unused hardware already in BIOS.
* Disable power hungry features.
* Enable CPU scaling if supported for ondemand CPU governor. DONT use powersave governor, typically uses more power than ondemand
(race to idle).
* Put network card to 100 mbit/10 mbit:
** 10 mbit: ethtool -s eth0 advertise 0x002
** 100 mbit: ethtool -s eth0 advertise 0x008
** Doesn't work for every card
* Put harddisk to spindown fast and full power saving:
** hdparm -S240 /dev/sda (20m idle to spindown)
** hdparm -B1 /dev/sda (Max powersave mode)
* Make sure writes to hd don't wake it up too quickly:
** Set flusing to once every hour
** echo "360000" > /proc/sys/vm/dirty_writeback_centisecs
** Enable laptop mode
** echo "1" > /proc/sys/vm/laptop_mode
* Screensaver needs to dpms off the screen, not just make colors black.  To turn of monitor after 120s when X is running:
** xset dpms 0 0 120

=== Simple programmer tips for improving power usage ===
* Wake up only when necessary
* No poll() calls
* If you wake up, do everything at once (race to idle)
* Use large buffers to avoid frequent disk access. Write one large block at a time
* Don't use [f]sync() if not necessary
* Group timers accross applications if possible (even systems)