Question About Mavericks Memory Management

Discussion in 'OS X Mavericks (10.9)' started by Traverse, Jul 7, 2014.

  1. Traverse macrumors 604


    Mar 11, 2013
    I have read in depth how Mavericks memory compression works because I find it fascinating, but one things seems curious to me.

    I've had a rMBP for about 20 days now and it has 16GB of RAM. I noticed that casual use (Safari, Mail, iTunes, Skype) caused memory compression (100-800MB), even with only 5 GB of RAM in use. I didn't really care, Mavericks is smarter then me.

    However, I also noticed that the system often swapped when I didn't see the need. The attached screenshot is not a drastic case, but one time I was using 6.5 GB of RAM and the system had 455 MB swapped.

    Why would the system swap memory with an abundance of memory? I thought the point of the advanced memory use was to avoid the swap.

    I mean, system performance isn't impacted; i'm just curious.

    Attached Files:

  2. Intell macrumors P6


    Jan 24, 2010
    It swaps because of how the system is designed. It tries to predict what you'll do next and adjust itself. Having some swap isn't bad. It's like having some body fat. You'll be an overall healthier person with a bit of body fat rather than with a very small amount to none at all.
  3. Traverse thread starter macrumors 604


    Mar 11, 2013
    I never thought to compare computer memory to body fat. :D

    Thanks for the input. Like I said, I'm bothered by it, I was just curious.
  4. h9826790, Jul 8, 2014
    Last edited: Jul 8, 2014

    h9826790 macrumors G3


    Apr 3, 2014
    Hong Kong
    The RAM compression may cause by high file cache at some stage without your notice (e.g. During time machine backup, or spotlight indexing, etc). That's completely normal. Even though my Mac has 32G RAM, it still occationally require to compress the RAM.

    With anything less than 300MB swap and stays there also completely normal. It may just cause by system operation, nothing about real RAM shortage.

    As long as the swap not keep increasing, and the memory pressure stays at green, there is almost nothing to worry about.
  5. maflynn Moderator


    Staff Member

    May 3, 2009
    I'd be more concerned about the ram pressure but that's only in the green, so I think given what you have shown, your memory management is fine.

    OSX does throw a little but of stuff into the swap file and does use the ram compression even when you don't think it needs too for some reason.

    I have 8GB and it too shows 500mb of compressed memory

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