[Alexia]

Where does this RAM go?
Mac Pro with 3gb RAM.

0.7/3.0 at start up.
1.0/3.0 after loading Firefox, Adium, Colloquy, and iTunes.

It will stay this way indefinitely. However if I load up and start playing World of Warcraft...
1.5/3.0 used while playing WoW, expected.
Later on...
2.0/3.0 then to 2.5/3.0 all the way until I have only 50mbs of RAM left.
Closing WoW brings me back to 2.5/3.0.
Closing all other applications brings me back to about 2.1/3.0.

So over the course of playing WoW, 1.1gbs of RAM magically disappears(Seemingly, sitting in inactive RAM.) and is no longer usable unless I reboot. WoW does invoke some memory leaks in Apple's OpenGL if you constantly switch between windowed and full screen, but both Apple and Blizzard claim that the RAM is returned by simply closing WoW. I do not do this, so that should not be the issue.

Where is the RAM "disappearing" too? Why can I not get it back with out rebooting?

[Big Mac]

This is a very common question. Modern OSs like OS X do not leave RAM completely "free" after applications use it. They cache application code for speedier future execution. Inactive RAM contains code that may be used in the future but may also be discarded if another application needs the space. In that sense, Inactive RAM is one of the most important indicators of your RAM usage: If you see a large amount of Inactive RAM (I say around 2/3s) that means you've got a greater than sufficient quantity of RAM for the application load you're currently running. If you only see a small amount of Inactive RAM (about 1/4th or less), you should consider adding more. The reason why you see all that Free RAM after rebooting is because the RAM is completely cleared with a reboot. That may sound good to you, but that's not the way to optimally manage memory. It has been stated many times before that free RAM is wasted RAM.

You should read Apple's FAQ on the subject.

[P]

Inactive is memory that could be freed quickly if there was a need for it. You can essentially consider Inactive+Free the same as the free memory under OS 9 or Windows. Apple is very honest but slightly misleading in reporting memory the way they do.

[rbarris]

The memory leak with switching between windowed and full screen was fixed by OS X 10.4.9.

You should find as you start to run other applications after quitting WoW, that the inactive number may start to drop. Note that disk caching can inflate memory usage numbers beyond what the application consciously requested.

Looked at another way, as long as the free RAM doesn't get down to zero, there's nothing to worry about. If on the other hand you are noticing explicit performance slowdowns after quitting WoW due to memory congestion (leading to excessive VM swapping to disk), than this is something we should look at more closely.

You can email us at wowmacteam123 "at" blizzard.com.