1GB swap file with no page outs

Discussion in 'OS X Mountain Lion (10.8)' started by musicwind95, Nov 16, 2012.

  1. musicwind95 macrumors newbie

    Joined:
    Aug 13, 2008
    #1
    Since the Macbook Pro Update 2.0, I've seen 1–2GB swap files upon waking, even if nothing else was even running (I had rebooted shortly before sleeping the system). However, I have 0 page outs. I was under the impression that data is swap is paged out from RAM, so to have data in swap I must have had page outs.

    How is it that I have a swap file with no page outs, and does anyone know what's going into this swap now (given that in this case, only Finder was running at the time)?

    [​IMG]
     
  2. Fishrrman macrumors G4

    Joined:
    Feb 20, 2009
    #2
    "How is it that I have a swap file with no page outs, and does anyone know what's going into this swap now (given that in this case, only Finder was running at the time)?"

    Just a guess (I'm sure someone with more knowlege will answer), but...

    Could it be possible that the OS creates and maintains a swap file, even if there are no page-outs, so that the drive space is "reserved" and the swap file will be "there and ready" in the event that page-outs become required?

    Kind of like having a fire station, with fire equipment and manpower standing by. You hope that you don't have to use them, but the local government wants them "there and ready", just in case....

    Having said that, there may be commands accessible via the Terminal app that let you manually remove the (unused) swap file...
     
  3. musicwind95 thread starter macrumors newbie

    Joined:
    Aug 13, 2008
    #3
    That's an interesting idea, but I don't think that's quite right.

    Upon waking it started out around 1.3GBs. It dropped off into the 900MBs a few minutes later.
    It's a rather arbitrary value if the system was simply allocating the space.
    Swap has never been too slow before.
    I'm on an rMBP with the new, fast flash storage.
     

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