I'm using a recent MacBook Pro with 8 GB of RAM and after a few hours of using it at work I notice the amount of 'active' memory growing and growing.
Whenever I reboot my Mac, everything looks fine and it is hardly using any RAM. But after a few hours it looks like this:
As you can see, in this case it's about 4.3 GB.
Being a developer, I know that 'active memory' is the amount of memory that is currently used by running processes. So the first thing I did was quitting all applications and killing all processes that don't seem to belong to Mac OS X.
After I did that, my active memory came down about 400 MB, but got stuck at what you see in the screenshot. There are no more processes or applications to quit.
Now I'm wondering what is actually holding on to the memory?
top and Activity Monitor don't report any processes with a high memory usage.
Thanks to Doug Harris' answer I made this screenshot. It shows an active memory usage of 2.55 GB system wide, but only a 1.55 GB memory usage which the
ps command calculates.
I'm not sure where the rest of the 2.55 GB is gone or where it is allocated. I have Instruments installed, but since this does happen over a span of a few hours, it is difficult to use Instruments. This feels like a memory leak somewhere in the OS. Maybe a driver (although I don't have any kernel extensions installed - checked with
Personally I think it would be interesting to be able to see "more" about the memory management status. Under Linux there is some information under "/proc" available, afaik.