As is most of the rest of the Windows-aware world, I’ve been following the various posts on the Building Windows 8 blog with great interest and regular attention. In fact, checking in on this blog has become part of my regular “keeping up with Windows” routine, and routinely serves as fodder for this blog.
A particularly interesting post popped up this past Tuesday (11/8/2011) entitled “Building a power-smart general-purpose Windows” from Pat Stemen, a Principal Program Manager on Microsoft’s Windows 8 OS Kernel development team. It not only details the design objectives for power consumption (less power, more efficiency, longer battery life) that inform Windows 8’s ongoing design, it also describes the kinds of testing and measurement Microsoft performs to keep those objectives on-target.
In that vein, I found Stemen’s recitation of how each Windows 8 build’s power consumption profile is measured particularly interesting, as was his explanation of what happens when occasional software changes introduce spikes in that consumption (ultimately such changes get tracked down and fixed to keep power consumption under control). It also sheds some interesting light on the powercfg.exe utility, and its energy parameter, already available in Windows 7 (as well as Windows 8).
This utility produces the output file identified near the end of the command’s on-screen output as captured above, and has lots of interesting things to say about how power is being managed (or not). The resulting HTML page includes a plethora of information about which drivers and power settings defeat or turn off power management functions (sleep, hibernation, suspension, and so forth). I also discovered some very interesting timer settings emerging from some surprising programs (TechSmith’s SnagIt and Google Talk, of all things), as well as pretty detailed list of which runtime processes were making “…significant processor utilization” to quote from those report headings.
This is an interesting blog post and is well worth reading. If you’ve never played with powercfg.exe before, either, it’s probably worth a try, too. Please launch cmd.exe using the right-click “run as administrator” option, though: otherwise, the program will refuse to run.