December, 2005

  • The Old New Thing

    Derren Brown's tips on being a psychic


    Magician and mentalist Derren Brown teaches us how we can all exercise our psychic powers, or at least use psychology to make people think we're psychic. The Video Clips page collects all the examples into one place for your viewing pleasure.

  • The Old New Thing

    Psychic debugging: Why your CPU usage is hovering at 50%


    Sometimes psychic debugging consists merely of seeing the bigger picture.

    On one of our internal bug-reporting mailing lists, someone asked, "How come when I do XYZ, my CPU usage goes to 50%?"

    My psychic answer: "Because you have two processors."

    The response was genuine surprise and amazement. How did I know they had two processors? Simple: If they had only one processor, the CPU usage would be 100%. This seems unhelpful on its face, but it actually does help diagnose the problem, because now they can search the bug database for bugs in the XYZ feature tagged "100% CPU" to see if any of those apply to their situation. (And in this case, it turns out that one did.)

  • The Old New Thing

    What one Windows XP feature am I most proud of?


    Of all the things I did for Windows XP, if I had to choose the one feature that I'm most proud of, it's fixing Pinball so it doesn't consume 100% CPU.

    The program was originally written for Windows 95 and had a render loop that simply painted frames as fast as possible. In the checked build, you could tell the program to display the number of frames per second. They reserved room for two digits of FPS.

    When I got to looking at Pinball's CPU usage, I built the checked version and took a peek at the frame rate. Imagine my surprise when I saw that Pinball's frame rate on contemporary hardware was over one million frames per second.

    I added a limiter that capped the frame rate to 120 frames per second. This was enough to drop the CPU usage from 100% to 1%. Now you can play Pinball while waiting for your document to print without noticeably impacting printing speed.

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