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2 v1.20. contents copyright 2014 Mark Minasi. Copying this without permission is really, really rude..

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Presentation on theme: "2 v1.20. contents copyright 2014 Mark Minasi. Copying this without permission is really, really rude.."— Presentation transcript:

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2 2 v1.20. contents copyright 2014 Mark Minasi. Copying this without permission is really, really rude..

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25 Let's say that Process "A" needs the CPU to wake up every 10 ms, and so creates a trigger that "fires" every 10 ms. Suppose the wake-up time is 3 ms after the trigger fires, and the time to do whatever A needs takes another 1 ms, like this: Wake 3 ms 6 ms nothing, CPU goes back to sleep A 1 ms Do whatever A needs done

26 A Wake A A A If we do several cycles, then, it looks like Result: the CPU sleeps about 60% of the time. Nice, from a battery drain point of view. Time

27 A Wake A A A Now let's add a second process, B, that also fires every 10 ms. As before, the OS needs 3 ms to wake up the CPU, and let's say that B's service time is also just 1 ms per fire… but it started later, unknowing of and out of phase with A: B Wake B B B Result: now the CPU only sleeps 20% of the time. Can we do better?

28 A Wake A A A This is nuts… we're wasting the CPU's time with unnecessary wake-ups. Wake B B BB Now the CPU sleeps 50% of the time! Answer: the OS forces A and B's timers to fire at the same time, burning less CPU time… and less battery

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38 Part of how Windows Store apps are built to be safer is by greatly reducing their access to the rest of the system; you see that in a new SID S-1-15-2-1 or "ALL APPLICATION PACKAGES" as in this screen shot of the DACLs for the Windows folder Also…

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61 www.microsoft.com/learning http://microsoft.com/msdn http://microsoft.com/technet http://channel9.msdn.com/Events/TechEd

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