Unused RAM?

in Genius Bar edited January 2014
So I usually have Activity Monitor opened in the dock with my memory use shown. I have 2 Gigs of RAM. When the computer starts up, about 5% is wired, 5% is active, 5% is inactive, and 85% is free. After normal usage for about an hour, I quit out of everything but memory is now 15% wired, 30% active, 54% Inavtive, and 1% free. Is there anyway for me to flush my RAM out (probably using the wrong term)? I know restarting my computer would do it but this is a Mac and I shouldn't have to do that; it shouldn't be doing this in the first place.

Any help would be appreciated?


  • Reply 1 of 5
    Wired = contents of RAM *cannot* be paged to swap files. These include system stuff and other low level stuff that must continually run.

    Active = Currently being used by programs and system, can be paged if necessary.

    Inactive = Contains *previously* used programs. *May* be used again if the same program is fired up, or it may be used by other applications.

    Free = Not used at all.

    So, when a new program is fired up, it has access to Free+Inactive. A small amount of Free memory is actually good, because it means that as much as possible, everything is in RAM, which is fast. A small amount is reserved in case the system needs to run any critical crash related stuff. Big amounts of inactive is also good, because newly started programs can use it if necessary.

    Clear now? I've simplified it a tad.
  • Reply 2 of 5
    Just to hammer home the point: Free ram is wasted ram. This is only a very slight exaggeration. You do not want large swaths of free ram.
  • Reply 3 of 5
    ipodandimacipodandimac Posts: 3,273member

    Originally posted by Karl Kuehn

    Just to hammer home the point: Free ram is wasted ram. This is only a very slight exaggeration. You do not want large swaths of free ram.

    well i usually have loads of free ram until i open up motion and final cut.
  • Reply 4 of 5
    I am not speaking from knowledge but I guess that free ram remains free until an application needs it. once the application is done using it it becomes inactive but not free.

    in a way it is cached - data that does not need to be recreated but is left as it is until it is needed to be overwriten with new data or used if requested.
  • Reply 5 of 5
    kickahakickaha Posts: 8,760member
    Bingo. The aggressive caching means lazy flushing, and that's a good thing.

    Free memory is a legacy concern, don't worry about it. You *want* as much as possible to be in RAM at any given time, it makes the system faster overall.

    Say you quit Mail. You then remember you forget that one last email, so you launch it again. With the current system, most of what Mail needs is already in memory, so it just maps to it again. Voila - much faster launch.

    Under your system, when you quit Mail it would go through and mark memory as freed (takes time), then have to load it all in from the disk again (takes more time). Net result: slower.

    Say you quit Mail and another app needs memory... it just takes it from the Inactive or Free zones, and there's no slowdown.

    Or if you switch to another app that's been swapped out to vm, and it needs to be loaded in, it just does so. No slowdown.

    There's no benefit to purging memory, and actually a decrease in performance.
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