Please help me understand system memory

[ipoddin]

I'd like a little better understanding of my memory usage. I go in to Activity monitor (or use a widget) and see "wired," "active," and "inactive"

What does each mean? For instance, currently I have Dashboard, Firefox, and Quicksilver running and here are the results:

Wired: 229.26mb
Active: 388.96mb
Inactive: 631.56mb

Free: 797.59mb

I'm using 1.2gb of memory and that seems like a lot. Now I do have alot of widgets, so I could try disabling some. However, right now, I'd just like to understand what all the memory readings mean. Thanks.

 

[emptyCup]

Wired: Memory that is currently in use for something so important that the application requires it to be in memory at all times

Active: Memory that is currently in use but which may be swapped out to disk when necessary (and brought back when needed)

Inactive: Memory that was in use but is not currently needed. It constitutes a cache of things that can be accessed quickly if they are needed again or disposed of if the space is needed for something else.

Free: unused. Typically only high after a restart. Free and Inactive together make up what most people think of as Free (available).

 

[ipoddin]

Free: unused. Typically only high after a restart. Free and Inactive together make up what most people think of as Free (available).

Ah. That makes it clearer. Thought something must be wrong. Thanks.

 

[WildCowboy]

For future reference, here is the official word from Apple on memory. But yes, emptyCup gave you a great explanation.