Mac RAM allocation question (probably a noob question)

Discussion in 'Mac Basics and Help' started by WickedRabbit, May 6, 2009.

  1. WickedRabbit macrumors regular

    Joined:
    Feb 17, 2009
    #1
    So I just bought my first Mac (an iMac with Ati 4850) and coming from the PC side I'm obviously a bit of a RAM whore in the sense that I'm always checking my available ram since I like to run a lot of things simultaneously and I'll also close things down that are a bit unnecessary if it's eating up a decent portion.

    Something I'm trying to figure out about the Mac is that it seems to handle RAM a bit different.

    Here's my situation (or what I've noticed at least):

    Lets say you turn on the iMac. From the start you have rougly 3.3-3.5gb of the 4gb available. I decide to do a little Photoshop work and listen to some music via iTunes and I've also got Adium and a Safari or FireFox open. On average, I notice this drops me down to about 1.8gb of ram (still a good amount) with Photoshop taking up the biggest chunk.

    Now, on Windows if you quit/shut down Photoshop, your memory was pretty much restored. However, on the Mac that doesn't seem to be the case - at least not in full. Say Adobe is eating 1gb (figuratively) and I shut it down. It will only restore a quarter of that to my available system ram.

    At first, I assumed the mac was sort of caching memory for applications that I've originally opened so that if I decided to open that app again it wouldn't use another 1gb since the 1gb was all ready being cached. However, that also isn't the complete case. If I re-open Photoshop later it doesn't use another 1gb, but still seems to be using an additional 25-50% of the original 1gb that it took when opening it the first time. Over the course of a day I sort of that I get incredibly close to that zero ram because I've been opening/closing applications and each time it takes a little more ram.

    From what I figure, it seems to be best to just leave an application always open once you open it on a Mac because you're not going to get your full ram back regardless.

    Is this common or is there something else I need to be doing?
     
  2. gr8tfly macrumors 603

    gr8tfly

    Joined:
    Oct 29, 2006
    Location:
    ~119W 34N
    #2
    Yes, it works different(ly). Here's a brief description of what you will see in Activity Monitor: Mac OS X- Reading system memory usage in Activity Monitor

    "Inactive" is still available for use by other apps, if needed, but if you relaunch the same app, it will launch much faster because it has cached memory.

    You don't need to worry about "getting back RAM" (as in "Free") - the OS does it when, and if it's needed.
     
  3. JNB macrumors 604

    JNB

    Joined:
    Oct 7, 2004
    Location:
    In a Hell predominately of my own making
    #3
    I wouldn't call it a noob question at all, but I would suggest that it's a waste of your time to worry about memory management on a desktop machine. Unix handles allocation differently than Windows, but very efficiently in the long haul, mostly because of RAM caching. (EDIT: beaten to the punch) Let the machine do its job, and just enjoy using instead of managing. Unless you're involved in highly intensive and mission-critical stuff I don't think it's really worth the bother. It hasn't been for me since I moved beyond a 4K RAM machine. ;)
     
  4. gr8tfly macrumors 603

    gr8tfly

    Joined:
    Oct 29, 2006
    Location:
    ~119W 34N
    #4
    4K - wow sheer luxury! My first had 1k :p (Altair 680b) Piggy-backed the DIP SRAM to a whopping 3K :)
     

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