When I originally read about PowerTOP from Intel, I figured it was designed completely for laptops. I decided to install it on my desktop with a Core2Duo and see what happens… strangely enough, it worked!
Although there is less data available when using a desktop CPU, it is certainly VERY useful in determining what is using the most power.
After installing PowerTOP using apt-get, I ran
sudo powertop -d which collects data for 15 seconds and spits out what is waking up the CPU from idle.
While running Firefox with multiple tabs, a few directories open in Nautilus, and I’m copying several hundred megabytes of files across SSH (to a USB external hard drive), we can see pretty clearly that copying files wakes up the CPU almost as much as running Firefox does.
30.7% (113.7) firefox-bin : schedule_timeout (process_timeout)
22.3% ( 82.5)
18.5% ( 68.6) firefox-bin : futex_wait (hrtimer_wakeup)
9.7% ( 35.8) Xorg : do_setitimer (it_real_fn)
3.5% ( 12.8) compiz.real : schedule_timeout (process_timeout)
3.4% ( 12.5) S20powernowd : queue_delayed_work_on (delayed_work_timer_fn)
2.7% ( 10.1)
2.2% ( 8.3)
1.3% ( 4.9)
1.1% ( 3.9)
What is really, really nice about PowerTOP is the tweaks that it suggests that are specific to your system, to lower power usage. I have a Serial ATA DVD drive. When PowerTOP noticed this, it actually suggested that I perform the following tweak to allow the drive to go into power saving mode more often:
hal-disable-polling –device /dev/scd0
Here’s a screenshot of what it looks like.. notice that you can just press the U key and perform the tweak. No command-line-fu needed here.
I could either run the command myself, or just press a key while that suggestion was up to conserve additional power. There were several tweaks that were suggested for my computer, and after doing them, I feel just a little bit better about “doing something for the enviroment.”
Thanks Intel for making me feel like a good person.