Actually, dlealval, I’m not sure how much we can trust the so-called “Memory” values, given for processes, within Activity Monitor, on Big Sur.
I don’t still have a Catalina system on which to test, but, as I recall, the values on Catalina seemed to “add up” better, there.
I run with the following memory related columns viewable: Memory, VM Compressed (Compressed Memory), Real Memory (RSIZE), Real Private Memory (RPRVT), Real Shared Memory (RSHRD), and Purgeable Memory.
On Catalina, it always seemed (but I could have simply missed cases where this wasn’t true) that Memory minus VM Compressed yielded Real Memory (RSIZE), which, in turn, equaled Real Private Memory (RPRVT) plus Real Shared Memory (RSHRD). Purgeable Memory always seemed to be a portion of Real Private Memory (RPRVT). (It wouldn’t make much sense for it to involve Real Shared Memory.)
If, in addition to the Memory tab, in Activity Monitor, you Inspect a given process, you’ll find the following Memory related counters, on the inspector’s Memory tab: Real Memory Size, Virtual Memory Size, Shared Memory Size, and Private Memory Size.
These counters with the same/similar names as the Column names, always seem to agree: Real Memory Size equals Real Memory (RSIZE), Shared Memory Size equals Real Shared Memory (RSHRD), and Private Memory Size equals Real Private Memory (RPRVT).
However, Virtual Memory Size is often much larger than the size shown in the Memory column! In fact, it can be so large that it cannot be physically accounted for even using all Real and “Swap” space, even if one uses a reasonable two to one (2:1) compression ratio for Compressed and Swap spaces!
However, this does not mean that this counter has no meaning, because Virtual Memory can include memory within the Virtual Memory space that includes the programming code of the App (this is “swapped” from the App’s files), as well as other, currently unused Virtual Memory space.
(I thought I recalled the Catalina “Virtual Memory Size” equaling the “Memory” column size, but I could be misremembering.)
It sure would be helpful to have further information on such matters, so we can know better how to interpret these various numbers.