6 Replies Latest reply: Jan 20, 2013 3:34 PM by jcsuperstar
dastoelk Level 3 (665 points)

I noticed how, in my acitivity monitor, a great deal of my RAM was tied up as "inactive memory."   I could not figure out a way to "free up" more space.


I ended up re-bootin my computer, and, as you can see from my screen shot, I know have PLENTY of RAM available.


Screen Shot 2013-01-17 at 4.49.31 PM.jpg


I have a BASIC understanding of "free" memory vs. "inactive memory." But, my questions are:


1.) What could I be doing to create so much "inactive" memory? (What applications processes tend to do this?)

2.) What is a way to immediately "free up" memory, short of rebooting?

OS X Mountain Lion (10.8.2), mid-2011 i7 24GB RAM, FCPX 10.0.7
  • stedman1 Level 9 (67,820 points)

    The Apple article below should help.


  • William Lloyd Level 7 (21,030 points)

    It's fine that there's inactive memory.  That can make some things faster.


    And 96 MB of "inactive" memory is next to nothing.  You have SO much free memory... unused memory is wasted memory ;-)

  • dastoelk Level 3 (665 points)

    Yes. But, I only achieved that scant amount of "inactive" memory (96 MB) only AFTER I rebooted.


    I used FCPX, could THAT be an application that shows a great deal of "inactive" memory when I shut that app down?


    Thanks for you help!

  • William Lloyd Level 7 (21,030 points)

    Certainly.  FCP X uses a lot of RAM.  As does Aperture (they can both use multiple GB of RAM).  Which is fine; the whole reason 64-bit applications can be faster is they can address > 2 GB of RAM in their process, which can make some things faster (videos and photos take a LOT of RAM to edit).


    Memory usage is pretty complicated.  There's a lot that goes on behind the scenes to optimize the performance of individual processes, as well as the performance of the computer as a whole. And the trouble with tools like Activity Monitor is that they're only giving you a coarse view of what's going on.


    I'd suggest you don't be alarmed, and in fact don't even pay attention.


    Here's really the only guideline I'd pay attention to: If you open up the System Memory tab and you see the "Page Outs" number growing, then the system is paging and needs more RAM.  At that point, I'd recommend you close down some applications, and the system will reclaim the RAM it needs to.  Rebooting frequently to keep the numbers low isn't really helpful, again because inactive RAM can be faster than active RAM if you re-launch an application.


    One note I'll make: I used to use a program called iStat Menus to track memory usage.  In a couple builds it had a HUGE memory leak to the point that my kernel_process was memory mapped to something like 164 GB of RAM (on a system with 12 GB of RAM).  So a COLOSSAL leak.  The tool was causing problems in the things it was attempting to measure!  Even then, that stuff was mostly paged out and the system wasn't much slower, because it wasn't _actively_ paging.  I uninstalled it ;-)  They since fixed the bug, I think, but honestly it's not really worth worrying about, unless the system is paging a lot (and with 24 GB of RAM, it shouldn't be, almost ever!).

  • BobHarris Level 6 (17,025 points)

    Inactive RAM is a cache to avoide expensive dusk reads.


    Expensive in time and power usage.

  • jcsuperstar Level 1 (10 points)

    has anyone tried the free app from the app store memory clean 2.3 developed by fiplab? that could be a help for the less computer savy.