RAM: inactive vs free?

[seebol]

I open Activity Monitor and see that out of my 768 MB of RAM, 304 MB is inactive while only 89 MB is "free." What is the difference between the two? Is this normal?

I'm running a 12" ibook, 10.3.4, and safari, itunes, dvd player, ichat, quicktime and activity monitor

 

[C-Mezak]

I open Activity Monitor and see that out of my 768 MB of RAM, 304 MB is inactive while only 89 MB is "free." What is the difference between the two? Is this normal?

I'm running a 12" ibook, 10.3.4, and safari, itunes, dvd player, ichat, quicktime and activity monitor

My guess would be that inactive RAM is ram that is in use (contains data) but is not actively being read or written. For instance, when you've left an app or two open but are not using them, there will still be some data held in memory about them, but it is inactive because the apps are stagnant and not being used. Free RAM would be RAM that is not being used at all.

Charlie

 

[bousozoku]

Inactive memory contains recently used application code (and hopefully not data) so that on re-launching, it can be done by a simple swap into real memory (RAM) without all the initialisation that normally occurs on a first launch of an application. Time is shortened immensly and users are happier. Unless, of course, they're trying to start something else and the system slows down because the inactive memory isn't purged immediately and things that are being used have to be swapped to the hard drive.

Apple still needs to refine this a bit. It would be nice to set a time limit and have inactive memory purged if an application hasn't been used for an hour or more.

 

[Darwin]

Inactive memory can be counted as free, well to me it is

If the program needs more memory and has taken all the free RAM it will start to take the inactive memory

so don't worry, if that RAM is needed it will be used

 

[MacsRgr8]

Apple still needs to refine this a bit. It would be nice to set a time limit and have inactive memory purged if an application hasn't been used for an hour or more.

Yep. Remember the Mac OS 9 util "Mac OS Purge?".
It would be fun if Apple made it possible to be able to "purge" your RAM, and also delete the extra swapfiles.

Edit: Eh.. ofcourse a reboot would be cheating