[slffl]

I just upgraded my 17" to 1gig. All I'm running right now is Konfabulator and the miniMon widget to check the memory. If I run some memory hogging programs (ie. iPhoto, Dreamweaver, Fireworks, Photoshop) and max out the memory, and the close everthing, I don't gain back even close to the memory. Right now it's showing 129MB free, and if I use Process Viewer, there are 2 or 3 proccesses taking 2% of memory, but that's it. Does anyone know how to get the memory back short of rebooting?

[eevyl]

You do not need to take care of "taking back" the memory. Mac OS X is smart enough to do it alone.

When you use some applications and close them, probably you don't see all the free memory you may think it should be, but this is because Mac OS X sort of "caches" some blocks of memory, just in case you open again the same application to save time. If you open another different application, this "cache" is overwritten with the new app. Don't worry about not having enough free memory.

[iohead]

Originally posted by slffl:
I just upgraded my 17" to 1gig. All I'm running right now is Konfabulator and the miniMon widget to check the memory. If I run some memory hogging programs (ie. iPhoto, Dreamweaver, Fireworks, Photoshop) and max out the memory, and the close everthing, I don't gain back even close to the memory. Right now it's showing 129MB free, and if I use Process Viewer, there are 2 or 3 proccesses taking 2% of memory, but that's it. Does anyone know how to get the memory back short of rebooting?

Mac OS X (like many other operating systems) uses what's called "paging". A page is a memory "block" of size 4096 bytes. The total memory you can use on the system is roughly the sum of the physical RAM installed + the size of the "swap" (a file or a partition on disk).

Now, a (physical/real memory) page can be in many states:

* free
* wired down
* active
* inactive
...

"wired down" refers to memory that you will not be able to use unless it's unwired, which typically won't.

"active" means the memory is currently in use by somebody and cannot be used by anybody else.

"inactive" means the memory can be used by other applications if the need arises.

"free" means the memory is not any of the above - it too can be used if the need arises.

Now, miniMon is displaying the "free" part, not the "inactive" part (which is not technically wrong, by the way). Under normal circumstances, the "inactive" part can be much more than the "free" part. On an iMac with 256MB of physical memory, here's what I have at the moment:

Wired: 32.4M
Active: 99.8M
Inactive: 112M
Free: 11.4M

This is nothing to worry about, and you don't need to reclaim anything.

In a virtual memory system with swapping, a visual (and aural) indication of "low memory" is when your disk grinds *a lot* as you launch applications.

-A

[javabeans]

Thanks for the detailed answer. I had the same concern so I pretty much closed all applications (Apple+Q). I guess I don't have to anymore!

[Powaqqatsi]

yeah but what I don't get is this. I have this:

Code:
PhysMem:  92.2M wired,  445M active,  275M inactive,  811M used,  213M free

and after launching an extra app (Illustrator) I get this:

Code:
PhysMem:  92.6M wired,  463M active,  330M inactive,  885M used,  139M free

Why is the memory from "free" used instead of the "inactive" ?

BTW: I have 167153 pageouts after ±10 days of uptime. And I don't have my RAM maxed out all of the time. OSX memory management isn't flawless at all like some suggest. (I have 1GB of RAM)

[iohead]

Originally posted by Powaqqatsi:
yeah but what I don't get is this. I have this:

Code:
PhysMem:  92.2M wired,  445M active,  275M inactive,  811M used,  213M free

and after launching an extra app (Illustrator) I get this:

Code:
PhysMem:  92.6M wired,  463M active,  330M inactive,  885M used,  139M free

Why is the memory from "free" used instead of the "inactive" ?

BTW: I have 167153 pageouts after ±10 days of uptime. And I don't have my RAM maxed out all of the time. OSX memory management isn't flawless at all like some suggest. (I have 1GB of RAM)

That's how it should be. Why should the memory manager use inactive memory (which *can* become active if those applications access the respective pages)? As long as there is free physical memory, it would be generally used for new requests.

I currently have an uptime of 5 days, and have 1375 pageouts (1 GB RAM). It would vary greatly depending on usage, and it does.

If by flawless you mean "perfect" (rather than bug-free), *NO* memory management is perfect, for that matter. It would be very surprising to find bugs in a critical piece such as the memory manager in a production OS that has been "out there" for long enough.

-A

[javabeans]

my uptime is only 16 hours and I already have 47509 pageouts. I've been running many different applications: iPhoto, iTunes, Eclipse (which is a resource hog), Safari, etc. The number is pretty high. Looks like I need to get extra RAM right? I only have 512MB