Macbook Pro memory questions...

Discussion in 'MacBook Pro' started by David.Prescott, Dec 9, 2014.

  1. David.Prescott macrumors newbie

    Dec 9, 2014
    If I am posting this in the wrong forum, please let me know.

    I have spent the last few days researching what I'm about to ask, and have yet to find a clear answer to my question: what is going on with my RAM/pages/swap?

    I have a new Macbook Pro 13-inch w/8GB RAM, 256 SSD, etc. It's the latest revision, and runs OS X 10.10. I just restarted. I am running the following:

    • Safari with 6 tabs (including this one!)
      Pages (with a 2 page text document)
      Steam (no games, just the client)
      Activity Monitor

    The following apps start with my computer, and run in the menu bar:

    • Evernote
      Display Menu
      Dropbox (not syncing anything, rarely does)
      iStat menus (CPU, RAM, HD, Network, Clock, Battery)

    Activity Monitor shows:

    Memory pressure around 15%.
    Physical mem: 8.00GB
    Mem used: 7.98GB
    Swap used: 0bytes
    App mem: 5.32GB
    File cache: 1.51GB
    Wired mem: 1.08GB
    Compressed: 0bytes

    iStats shows 431,731 Page Ins, 29 Page Outs

    I think I have a good handle on how OS X works with memory, so I know that seeing "Memory Used" at 7.89 is actually a good thing.

    What I don't understand is how I am getting Page Outs on this system. Why do I have Page Outs when I have 1.5GB of RAM in file cache? Why am I getting Page Outs (which as I understand means I may be running out of RAM) when Memory Pressure is at 15%? To make things even more confusing, I sometimes see Swap Used as >0bytes AND Page Outs AND low memory pressure.

    Since starting this post a few minutes ago, my Memory Pressure has held at 13%, yet my Page Outs have increased to 47. And I'll I'm doing is typing this post.
  2. GGJstudios macrumors Westmere


    May 16, 2008
    You have no swap used and your page outs are trivial. You have plenty of memory available. You don't need to worry about it.

    It is quite normal for all of your memory to be in use by OS X. It does not mean that you are running out of memory or that it is maxed out. OS X will manage all available memory, making it available to apps on an as-needed basis. Refer to the following Apple support article for more information on how to understand your Activity Monitor readings.
  3. David.Prescott thread starter macrumors newbie

    Dec 9, 2014
    Thanks GGJstudios.

    Yeah, I know that unused RAM is wasted RAM, so I'm not worried about that. I'm more confused by Page Outs and Swap Used (in some situations), when it seems that I have plenty of RAM.

    For instance, after I posted this question I searched MacRumors forums to find more information. I've opened a bunch more tabs. Memory Pressure is at 17%, other Activity Monitor numbers look fine (I only have 600MB File Cache, and now 100MB of Compressed Memory), but my Page Outs have increased to 428.

    I'm probably overthinking all of this, and should just use the computer.

  4. GGJstudios macrumors Westmere


    May 16, 2008
    Remember Page Outs are cumulative since your last restart. You can run for days or weeks with no Page Outs, then run into a brief period of intense activity that causes a few Page Outs. Those will remain on your reading until you restart. Again, your Page Outs are minimal, and shouldn't be any cause for concern.
  5. leman macrumors G3

    Oct 14, 2008
    Because there are a lot of reason to get a page out and not all of them have to do with lack of RAM. A page is 4KB. Having 428 page outs means that the OS has decided to back up 1.5MB of memory to secondary storage — for whatever reasons.

    OS X memory management is insanely sophisticated and complex. What you see in Activity Monitor is just a gross simplification. If you want to get a better understanding of that complexity, run the command vm_stat in the terminal - it shows you the current statistics of the memory subsystem.

    In the end, nobody will tell you why your system has page outs. To fully understand this, one would need to read through the thousands of lines of the FreeBSD and OS X kernel code, profile your applications and simulate your usage patterns dozens of times. If you are not being any performance issues, then there is no reason even to think about it.
  6. David.Prescott thread starter macrumors newbie

    Dec 9, 2014
    Ok, thanks.

    I'm just going to use the computer and never open Activity Monitor again and obsess. Or at least not that often. Probably.


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