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Microsoft outlines the enhanced power efficiency of Windows 8

Microsoft’s latest OS features “power hygiene”-a set of features that improve the efficiency of batteries for mobile gadgets and computing devices. Unlike previous OS series’ egalitarian treatment of active and inactive applications when it comes to machine resource allocation, Windows 8 stands to be more intelligent regarding the allocation of precious power resources.

According to the official Microsoft blog, the company notes: “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.” This means that this power management is more discriminating and can tell between applications you want operating in the background and inactive processes. This rules out the situation where the system stops an application that is copying files as a background process.

As part of “power hygiene”, an application can be in one of three states: foreground operation, suspended background operation or active background operation. Accordingly, software that you are actively using or viewing gets unlimited access to system resources. This is generally similar to previous Windows OS’ power management schemes with a few tweaks. The suspended background operation state applies if you swith from one app to another or to the desktop. Once Windows detects this, Windows 8′s CPU access scheduler will overlook the unused software. No system resources will be allotted to it although it remains cached. According to Microsoft, this state actually speeds up switching between apps since the system will no longer be burdened by how many programs are concurrently running. This is very unlike past Windows versions’ handling of concurrent applications-all open apps draw resources simultaneously and the whole system is burdened as a result.

According to Microsoft, “Since the notion of what is running is abstracted, we have made launching an app and switching to an app essentially synonymous…Whether you switch to an app using the back stack, or Alt+Tab, or the Start screen, you can get back to a suspended app instantly. In this way, the list of ‘running’ programs is for all practical purposes the same as the list of programs you see on the Start screen.” In addition to being able to quickly access “inactive” apps, the suspended software will still be able to do live updates of tiles. It will feel like these apps are still running with full resources. “Suspended” state apps will be stored in data storage (hard drive) instead of RAM. This frees up precious system memory resources.