In a new Building Windows 8 blog post, Microsoft goes over how the company has improved power efficiency for applications in the company's upcoming Windows 8 operating system. The company goes over the three different power states that Metro Apps will utilize.
"For Windows 8, we started off with a rule that would apply to the large majority of Metro style apps: if an app is not on screen, and the screen is not on, it should not impact your battery life," Microsoft stated in an official blog post.
In Windows 8, apps will be actively running in the foreground by running and utilizing CPU, disk, memory and other resources as needed. If they are not running, they are suspended in the background and will not be using the CPU, or performing some defined background activity. "Metro style apps are essentially the same as Windows applications have always been," Microsoft adds.
"Fast and responsive apps are built on a solid foundation of asynchronous programming. Leveraging techniques like these will help deliver great scenarios and foreground performance for apps, and extend battery life," Microsoft states.
Microsoft further explains the new sleep state in Windows 8 by describing exactly what it will do. "By the time Windows 8 is released, there will be a broader range of PCs available than ever before. Many of these will have similar power options to those running Windows 7 today. Besides turning off completely, they will be able to go into a 'sleep' state, either on demand, or after a period of inactivity. During sleep, all system activity is completely suspended."
Microsoft has also added a new component to Windows 8 called the Desktop Activity Monitor. "This component is designed to help reduce the resource utilization of desktop apps when the device goes into connected standby. If we allowed apps to continue running unchecked in this low-power mode, the PC would run down the battery more quickly. Instead, we suspend desktop applications, stopping their resource use and maximizing battery life. From the applications’ perspective, it will appear as if the PC has simply been put to sleep. When the PC is woken from connected standby, the app will resume as if the PC had been woken from a sleep state," Microsoft explains.
All legacy apps will continue to function like before but new Metro styled apps can harness the power-efficient model that Microsoft has come up with. "Applications that were designed for Windows 7 will continue to work as they have before with no change in behavior, and new Metro style apps can be developed to enable new connected experiences that work in a more power-efficient manner, by taking advantage of the background infrastructure that the operating system provides."