updated 09:10 pm EST, Tue February 7, 2012
Windows 8 to be much more aggressive on power
Key Microsoft program managers Sharif Farag and Ben Srour on Tuesday gave a detailed outline of how Windows 8 will manage Metro apps to control power. While the two stressed that multitasking will still be active, the principle will be to devote attention almost exclusively to apps in the foreground. If in the background, especially if the screen is asleep, it should be having no impact on the battery, they wrote.
Similar to Apple's approach to multitasking, Microsoft is mostly keeping battery life up by focusing only on the most common instances where it's needed, such as background file transfers, audio, messaging and voice apps, and device syncs such as with a smartphone. Notifications both have typical live tile notifications as well as push notifications that need to sip data online.
Windows 8's suspended apps will sit in memory but will have virtually all their program threads killed in that state, effectively taking up a zero footprint on the processor and battery life as a result. Live tile notifications can help keep information coming relating to an app without having to reload it. Microsoft did warn, though, that it will completely stop an app if the PC is running low on memory.
Certain tasks always have to be running, such as drivers and security tools. However, Farag and Srour promised that many of these would be "throttled" to keep them from sapping too much energy when they're not needed.
Windows 7 or other traditional desktop apps would still have full multitasking support. ARM-based devices won't run Intel-based code, though, making Metro the most common environment for Windows 8 tablets and thus keeping them running for longer as a whole.
Windows 8 will get a public preview version for download in late February. A finished release is expected to ship in the second half of 2012.