How does virtual memory work?

Discussion in 'Mac Pro' started by WillMak, Jul 30, 2006.

  1. WillMak macrumors 6502a

    Jul 29, 2005
    I am very confused right now. Activity monitor says that I am using 15.55 GB of Virtual memory...but I only have 11 gigs left on my hard drive?
  2. poppe macrumors 68020


    Apr 29, 2006
    Woodland Hills
    My Dell always Said... Windows doesn't have enough and needs to make more... Like it notifies me... why can't it just make more...

    What ever it is in the first place...
  3. gekko513 macrumors 603


    Oct 16, 2003
    A possible explanation is that several of the processes have memory pages that are equal and "shared" until one of the processes writes to those pages. I found support for that explanation on Apple's developer pages:
    Most applications link to and use the same frameworks from Apple. It would make sense if the memory for these frameworks weren't physically duplicated, but since the memory is mapped from all processes, it may still show in each ones virtual memory usage.

    I don't know if this is the case, though. It's just a theory of mine.
  4. Mitthrawnuruodo Moderator emeritus


    Mar 10, 2004
    Bergen, Norway
    You need to go easy on the Widgets, there... ;)

    In my experience, whenever the VM size exceeds the free space on your boot drive your Mac slows down, because then the system needs to search for space to page into... so you need to downsize your VM size and/or free up some hard drive space... ;)

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