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Lennyvalentin

macrumors 65816
Apr 25, 2011
1,431
788
How much memory it "should" use is a relative term, and may actually vary depending on your use, because some OSes pre-load apps just in case you decide to use them, so that app startup will feel snappy. I'm not sure if macOS does this though but windows has done it since the vista days IIRC. This caused anguish in some retentive people who saw the OS as 'wasting' memory, even though A, you literally have no use whatsoever for free RAM just sitting there doing nothing, and B, any pre-loaded data would get nuked instantly if a running app needed the RAM for something else.

So the answer might well be "it depends". :)
 
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Lennyvalentin

macrumors 65816
Apr 25, 2011
1,431
788
According to Activity Monitor and the logs in Console my Mac is never "idle".
True, computers are virtually never really 100% idle. There's always background stuff to do which causes some amount of activity even if you as a user aren't doing a thing. This is normal. :)

Even back in the bad old days of early home computers, the CPU (if not doing anything in particular) would take time off from spinning in an idle loop to do stuff like scanning the keyboard input lines to check for pressed keys, or even refreshing DRAM, if the system lacked a dedicated memory controller or DMA channel or similar for such a task.
 

Suttree

Suspended
Jul 21, 2018
232
327
I'm sure there's no right answer to this, but, out of curiosity, with 8GB, my system is using 2.5GB.
 

NewUsername

macrumors 6502
Aug 20, 2019
412
774
An old thread, but I was wondering about this as well. I have 8GB and my system uses 2.9GB. I have seen systems with 4GB using less RAM, and systems with 16GB using more RAM. My question is: when would the amount of RAM the system uses stop increasing? So I would be interested to hear how much RAM your system uses when idle if you have 16GB RAM, 32GB RAM, 64GB RAM,… There got to be a maximum; I can't imagine a Mac Pro with 1.5TB RAM will use up 1TB RAM when idle.

Anyone?
 

avz

macrumors 65816
Oct 7, 2018
1,326
1,472
An old thread, but I was wondering about this as well. I have 8GB and my system uses 2.9GB. I have seen systems with 4GB using less RAM, and systems with 16GB using more RAM. My question is: when would the amount of RAM the system uses stop increasing? So I would be interested to hear how much RAM your system uses when idle if you have 16GB RAM, 32GB RAM, 64GB RAM,… There got to be a maximum; I can't imagine a Mac Pro with 1.5TB RAM will use up 1TB RAM when idle.

Anyone?

Somebody once said that unused RAM is a wasted RAM. macOS is designed to utilise as much RAM as possible . I remember the very first iteration of Mojave 10.14.3 was running great with only 2GB, now 4GB is simply not enough.
 

KALLT

macrumors 603
Sep 23, 2008
5,229
3,285
An old thread, but I was wondering about this as well. I have 8GB and my system uses 2.9GB. I have seen systems with 4GB using less RAM, and systems with 16GB using more RAM. My question is: when would the amount of RAM the system uses stop increasing? So I would be interested to hear how much RAM your system uses when idle if you have 16GB RAM, 32GB RAM, 64GB RAM,… There got to be a maximum; I can't imagine a Mac Pro with 1.5TB RAM will use up 1TB RAM when idle.

Anyone?

If that Mac Pro has accumulated large caches during runtime, then I do not see why not. The system will use the RAM for caching, i.e. keeping data in memory rather than purging it. What is already loaded into memory does not have to be loaded again. If the system has little RAM to begin with, it will need to purge it sooner to maintain a low memory pressure and be able to respond to upcoming memory usage.

It’s like a whiteboard. You can draw as much as you want on it and wipe parts at any time. But you don’t have to wipe it immediately, especially if you might need what is written on it at a later point. The larger the whiteboard, the larger the surface. If you don’t actually use as much of the whiteboard, then most of the surface will stay clean of course.
 
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