Why is it that when OS X freezes the mouse still moves?

Discussion in 'macOS' started by Esulatell, Apr 17, 2009.

  1. Esulatell macrumors member

    Joined:
    Jan 4, 2009
    #1
    I've always wondered this, when my Mac gets the little beach-ball and everything freezes (I have to hard-restart), why does the mouse still move? :confused:
     
  2. Tallest Skil macrumors P6

    Tallest Skil

    Joined:
    Aug 13, 2006
    Location:
    1 Geostationary Tower Plaza
    #2
    I'll bet you that not everything is frozen. It's nigh-on impossible to freeze the entire system short of a kernel panic (and you'll know when you have a kernel panic...).

    Try just Force Quitting the unruly application.
     
  3. Esulatell thread starter macrumors member

    Joined:
    Jan 4, 2009
    #3
    Ah but force quitting doesn't work because the menu bar has frozen too.
    Plus the keyboard shortcut doesn't either.

    But what happens during a kernel panic? :confused:
     
  4. Mal macrumors 603

    Mal

    Joined:
    Jan 6, 2002
    Location:
    Orlando
    #4
    Technically, what you're seeing is not a freeze (though it's only a technical distinction). What's happening there is that some program is using up all of the CPU cycles, and so while the other programs are theoretically unaffected, they can't do any CPU time to do anything. It's like trying to talk to someone who won't shut up and so you can't get a word in edgewise. Oftentimes you can just wait and eventually one of them will slip through a command, but that could take a while, and you just hope it's what you needed to get some time in (like the Force Quit command, which you can trigger with Cmd-Opt-Esc, if you can't use the Menu bar). That's why the mouse still moves though, because the mouse cursor lives in the firmware and the graphics subsystem, so the CPU isn't involved in the movement of the cursor.

    A kernel panic, btw, will result in one of two things: either a gray curtain will drop and a message will show up saying you need to restart your computer in 4 different languages, or white text on a black background will start filling up the screen and essentially give you the same message. The first is far more likely unless you're running an older system.

    jW
     
  5. Tallest Skil macrumors P6

    Tallest Skil

    Joined:
    Aug 13, 2006
    Location:
    1 Geostationary Tower Plaza
    #5
    Click into a different application via the Dock or by clicking on the Finder. You'll gain access to that app's Menu Bar.
     
  6. Esulatell thread starter macrumors member

    Joined:
    Jan 4, 2009
    #6
    Essentially a BSoD?
     
  7. SnowLeopard2008 macrumors 604

    SnowLeopard2008

    Joined:
    Jul 4, 2008
    Location:
    Silicon Valley
    #7
    Yes and No. No because BSoD occurs before the OS has loaded. And yes because either way (BSoD or kernel panic) you need to reboot.
     
  8. John Jacob macrumors 6502a

    John Jacob

    Joined:
    Feb 11, 2003
    Location:
    Columbia, MD
    #8
    That's not true - you can have a BSoD at any time too. In fact, they a kernel panic in Mac OS X and a BSoD in Windows are quite equivalent.
     

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