Power Savings Basics

Uninterrupted sleep Everyone feels more refreshed after a good night's sleep. It's how we get powered up and ready for a new day. How energetic would you feel in the morning if someone had been waking you up every five minutes during the night?

Recharging without interruptions Systems need to time to refresh their power, too. Power management hasn't been a conscious focus of software design up ‘til now, so it's not surprising that computers are far less energy efficient than they could be. Currently, the system actively checks in on every application through polling and timers to make sure everything is running fine. Power management considerations place the burden on the application to wake the system when they need something, so the system has an opportunity to recharge in the downtime. The less it's interrupted, the more and better recharging it can do.

Race to idle The principle is the same one cheetahs live by, run hard and then sleep hard and long. This method only works if you save a lot of energy while you're sleeping. If you can't, then it's better to work slower.

Simple savings What are some simple ways to keep your system asleep when you don't need it?

• Turn it off If you don't use a device, turn it off. Even if you're not using it, if it's on, it's still consuming power. So, for example, if you're not playing audio, close your audio player application.
• Create long idle time between activities Processors (but also disks and many other components) have several degrees of saving power when they are idle. If a component is idle for a long time, it can go into the deepest possible power saving state, while if it's only idle for a short time, it can only go into a shallow power saving state. It depends on the component type what defines "long time", for processors, a "long time" is roughly around 20 miliseconds, while for disks this is around 2 seconds. While the scale differs for these components, the net effect is the same: it is better to do all the work in one step than to have several smaller steps.