Instruments VM Tracker lists Dirty twice

Question

This post gives a good explanation of the difference between Resident and Dirty memory. I found even more information listed here.

I am trying to understand more of what Instruments is trying to tell me. It appears to use the word Dirty in 2 different ways. First it uses 'Dirty Size' to description each category. Then it has an entire category called '*Dirty*' which also has a Dirty Size.

Is the *Dirty* category a set separate allocations? Is it unrelated to the DirtySize?

Answer 1

The Dirty category (in the Type column) contains all the memory regions with dirty memory. The Dirty Size column tells you how much memory in each memory region is dirty. Because the Dirty category contains all the memory regions with dirty memory, the Dirty Size column of the Dirty category equals the Dirty Size column of the All category, which you can see in the screenshot you posted.