ram distribution

rafarafa
Posted:
in macOS edited January 2014
Hey guys, I just received my MB last week and I installed 2GB of ram in it. I opened up Activity Monitor just to see how much ram was being used and free, and even when I don't have any programs opened it says I only have a little over 1GB free. I was wondering where all the memory was being used. I know there are some programs opened in the background, but certainly not 1GB worth. Also, could anyone explain what the "wired," "active," and "inactive" terms mean under the Activity monitor? Thanks.

Comments

  • Reply 1 of 4
    hirohiro Posts: 2,663member
    OS X intelligently doesn't trash stuff that is already in RAM. It keeps it around just in case it is needed later. If it needs to be moved to the VM backing store, it will be. If it's not needed, but memory space is, it will be overwritten, but not until it absolutely needs to be. OS X just looks at RAM like another level of cache, and cached is faster than not cached.



    What you are seeing is a good thing.



    Ignore the free space number, it's only used by the OS to determine when it needs to reclaim RAM or move something to the VM backing store. Free space is all but meaningless to a user.



    Wired memory are memory pages that are not swappable, usually OS specific regions or shared code. Active identifies the collective size of memory pages in recent use. Inactive means the memory pages were in use, but have not been accessed recently.



    wired+active+inactive approximately equal used memory. The numbers are not exact because we are displaying approximate base10 numbers but the actual math is done in base2 (binary).
  • Reply 2 of 4
    lundylundy Posts: 4,466member
    The more RAM is in use, the better.



    Having "free" RAM is not something you want - you paid for it, and Mac OS X will try and use it whenever possible. The more things it can cache in RAM, the faster it can access them when you need them again.



    Ideally, if there were enough things to cache, you would like to see 80%-90% RAM used. In fact, if you were to open and use 10-20 apps and then close them you might see that happen. It's a good thing.
  • Reply 3 of 4
    rafarafa Posts: 25member
    Ah, it makes sense now. I always thought that the more free ram the better, but I see what you guys are talking about. Thanks a lot for the information guys!
  • Reply 4 of 4
    smnsmn Posts: 13member
    Here's a good explanation straight from Apple:

    http://docs.info.apple.com/article.html?artnum=107918



    -S
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