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Old 05-05-2012, 10:25 PM   #1
GavinBKK
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Understanding RAM usage.

iMac 24", 2006, SL, 4Gb RAM:

Currently have TotalFinder open with 2 tabs, Safari with 3 tabs and 5 documents open in Preview. For the purpose of this post, Activity Monitor is also open.

Of my 4Gb, 1.07Gb are free.

Why is my system using so much RAM when doing so little?
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Old 05-06-2012, 05:26 PM   #2
ganbustein
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If you have any free memory at all, you're wasting RAM. That's RAM you bought and paid for but haven't even touched.

How much Inactive memory do you have? That's RAM that has been used, but isn't being used right now. The system is remembering what it used that RAM for, and what information is still in it, so if you need it again the system can just grab it again without having to read from disk. Think of "Inactive" as "automatic RAM disk".

You haven't told us what's on those 2 Safari tabs, or the 5 Preview documents. As long as you have Free (as in "otherwise going to waste") RAM, both apps will try to find a use for it. Preview might cache entire documents in RAM; Safari will likely try to cache everything on those two tabs, plus as much as it can from your pages in your history. Such cached information will show up as "Inactive". Any other application that needs the RAM will get it by borrowing from that "Inactive" memory (but only after all Free memory has been eaten up).

Basically, the system will just keep piling more and more into Inactive memory until you finally run out of Free memory, and only then is there any point in trying to manage RAM better.
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Old 05-06-2012, 07:50 PM   #3
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The preview docs were single page .pdfs, although one was a whole two pager. The Safari tabs were a forex website and a military vehicle parts dealership, neither had any live front end stuff.

I understand everything you said above, but I just can't get my head around the system using 3Gb for those paltry tasks.
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Old 05-06-2012, 08:11 PM   #4
DeltaMac
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1.07 GB free does NOT mean that the rest is, somehow, wasted by those few apps that you listed.
How much of that 3GB 'in use' is active, and how much is inactive? Wired?
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Old 05-06-2012, 08:17 PM   #5
NaOH
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Quote:
Originally Posted by GavinBKK
I understand everything you said above, but I just can't get my head around the system using 3Gb for those paltry tasks.

Two things I'll note. One is that you do have a bunch of background processes that run. We all do. Things like loginwindow, SystemUIServer, Quicklook Helper, AppleSpell.service, mdworker, and probably a few others, not to mention any third-party background processes you may have. On my Mac which hasn't been restarted in a few days, those processes I listed are using about 200 MB of real memory and 900 MB of virtual memory. All in all, I only have about 140 MB of inactive memory. That's okay, means the RAM is being used, though I do have a lot of page outs, so I'm due for a restart

Much more importantly, the processes you launched aren't "using 3Gb" of RAM in the sense that they need them. It's more like the memory is available so the system is allocating a lot to them. Start opening other applications which require sizable amounts of RAM, and the system will adjust. Until then, it makes sense for the system to give a lot of support to whatever can use it.
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Old 05-06-2012, 11:02 PM   #6
GavinBKK
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Free: 440
Wired: 258
Active: 1.16
Inactive 1.17

Things appear to have settled overnight, as FreeMemory in the MenuBar was flashing a red low double-digit figure at me yesterday. All day.
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Old 05-07-2012, 02:53 AM   #7
benwiggy
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Quote:
Originally Posted by GavinBKK
FreeMemory in the MenuBar was flashing a red low double-digit figure at me yesterday. All day.

That would seem to be some sort of utility that makes you worry about memory usage.

OS X handles memory usage for you. You don't need to worry about it, monitor it or check it. I presume your Mac is maxxed out for memory. Best just to let OS X get on with the tasks that it does, so that you can do the tasks that you want to do, rather than wasting time overseeing memory management.
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Old 05-07-2012, 04:51 AM   #8
GavinBKK
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No, I absolutely agree, it's just that I am actually interested in how it works and my interest was piqued when I saw these red numbers flashing at me, yet the machine was functioning perfectly normally.
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Old 05-07-2012, 06:58 AM   #9
DeltaMac
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Just a reminder - on your 24-inch iMac - only 3GB of memory is addressed, so your free memory, etc, is figured on that total of 3GB, not 4GB that you have installed.
So, in a sense, you will always have 1GB that is 'wasted' (not really wasted, but just not available)
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Old 05-08-2012, 05:16 AM   #10
GavinBKK
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:-( So much for the OWC website then...
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Old 05-08-2012, 05:50 AM   #11
acme.mail.order
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The 2006 24" iMacs had a 3Gb memory limit. If you'd waited just a little bit.....

My 2008 model has 6Gb installed and working happily. Right now I have 290Mb free and about 3Gb of paged memory in the swapfiles.
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Old 05-08-2012, 05:52 AM   #12
GavinBKK
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I know...

And everyone says "Don't wait, you can wait forever. Get what you need now..."

I'm up for a new 27" iMac and I am waiting!
;-)
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Old 05-08-2012, 07:21 AM   #13
DeltaMac
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Don't complain too much about OWC...
The OWC site is correct, and accurate, too!
http://eshop.macsales.com/Descriptio...maclate06.html
Quote:
OWC Memory Note:
Although limited to physically utilizing a maximum of 3GB, there is a performance benefit due to 128 Bit addressing when 4GB (2GB x 2 Matched set) is installed.

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Old 05-08-2012, 07:32 AM   #14
GavinBKK
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Fair enough. I dealt with the online help person/robot. Much cheaper than we can get here anyway.
:-)
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