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Gordon Messmer
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@Tomislav Tustonic I'm not going to assert that all of the claims in that paper are true, but I've read through all of your links. There's almost no questioning or debunking in Schneier's blog, and some of the other blogs "debunking" the paper are very clearly incorrect. Some of those are contradicted by Microsofts own answer to Guttman's paper, which includes: "Will Windows Vista content protection features increase CPU resource consumption? Yes" Guttman may be wrong about a number of his claims, but I'm not sure zdnet bloggers are really much more accurate.
Found it: "In order to prevent active attacks, device drivers are required to poll the underlying hardware every 30ms for digital outputs and every 150 ms for analog ones to ensure that everything appears kosher. This means that even with nothing else happening in the system, a mass of assorted drivers has to wake up thirty times a second just to ensure that… nothing continues to happen" So there you go, your video and audio drivers have to poll the hardware repeatedly, which takes all of the CPU, video, and audio hardware out of low-power state when they could otherwise be idle. As far as I know, this remains the spec for drivers, and does partially explain why Windows would use more power at idle than other operating systems.
I vaguely recall someone from AMD (??) writing a paper back when Vista was introduced that went over the implementation of driver signing in Windows, and how that was going to impact battery life. Basically, as I recall, in order to implement DRM the OS will repeatedly check the drivers and the hardware to make sure that all signatures remain valid, so it doesn't really idle well at all.
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Oct 21, 2013