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mac OS Catalina using much more ram comparing to High Sierra and Mojave

ewu

ewu

macrumors regular
Original poster
Apr 14, 2020
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iMac runs mac os High Sierra 10.13.6
MBP 16inch runs mac os Catalina 10.15.4

both iMac and MBP 16inch have 64GB ram.

I open same projects in vscode, same java projects in same version of eclipse and run an ubuntu vmware configured to take 4GB ram, a simple docker container.

High Sierra takes 20GB ram
Catalina takes almost 30GB ram

each single app Catalina takes more ram as well, from Active Monitor.

Personally I feel very bad about Mac OS Catalina on ram consuming.

what do you see about ram consuming of mac os Catalina in your mac?
 
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chrfr

chrfr

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Jul 11, 2009
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turbomacs said:
64-bit apps take up more of everything ... disk space, RAM, CPU cycles.
Click to expand...
That's only relevant if the apps in question were 32-bit prior to the Catalina upgrade.
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ewu said:
iMac runs mac os High Sierra 10.13.6
MBP 16inch runs mac os Catalina 10.15.4

both iMac and MBP 16inch have 64GB ram.

I open same projects in vscode, same java projects in same version of eclipse and run an ubuntu vmware configured to take 4GB ram, a simple docker container.

High Sierra takes 20GB ram
Catalina takes almost 30GB ram

each single app Catalina takes more ram as well, from Active Monitor.

Personally I feel very bad about Mac OS Catalina on ram consuming.

what do you see about ram consuming of mac os Catalina in your mac?
Click to expand...
I haven't paid attention, but I'd have been annoyed if I'd paid for 64GB and was only using 20. I don't see any issue in the system using 30. With the way macOS caches data, you can't draw any useful conclusions about RAM usage until you start to use all of your RAM.
 
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turbomacs

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Feb 5, 2020
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posguy99 said:
Based on what? Especially the last one, but surely you're not going to pop some screed about how 64-bit is twice 32-bit or something?
Click to expand...

64 bit addresses take up twice as much space in memory and in the cache (potentially causing more cache misses), and twice as much bandwidth when they're being passed around the bus. If an application does a lot of processing using address pointers then it's likely more cpu cycles will be consumed when that application is compiled for 64-bit compared to a 32-bit compile.

Basically if the code is very efficient (most isn't) and written specifically with 64-bit optimization in mind, then the CPU penalty specifically isn't that bad, or it could be better. Catalina is the first all 64-bit OS Apple has released and I imagine a lot of the code base is just 32-bit code recompiled for 64-bit, so there is a lot of clean up and optimization that needs to be done. I hope we get a Catalina 2 like they did with Leopard -> Snow Leopard that cleans up a lot of crap code in the OS and bundled Apps.
 
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Eliott69

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Mar 16, 2019
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turbomacs said:
64 bit addresses take up twice as much space in memory and in the cache (potentially causing more cache misses), and twice as much bandwidth when they're being passed around the bus. If an application does a lot of processing using address pointers then it's likely more cpu cycles will be consumed when that application is compiled for 64-bit compared to a 32-bit compile.
Click to expand...
That is not correct – not at all.
 
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posguy99

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Nov 3, 2004
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turbomacs said:
Basically if the code is very efficient (most isn't) and written specifically with 64-bit optimization in mind, then the CPU penalty specifically isn't that bad, or it could be better. Catalina is the first all 64-bit OS Apple has released and I imagine a lot of the code base is just 32-bit code recompiled for 64-bit, so there is a lot of clean up and optimization that needs to be done.
Click to expand...
Uh, macOS has been 64-bit for quite a while now. It has been carrying around 32-bit compatibility libraries which Apple has now jettisoned.
 
ewu

ewu

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Original poster
Apr 14, 2020
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I don't think it is 64-bit issue, all apps I uses in iMac and MBP 16in are 64-bit. (MBP 16in is perfect laptop in hardware by the way, but it would be more perfect if it is shipped with Mojave)

I disable Spotlight search as well in both systems, "sudo mdutil -a -i off".
I also check new process PID generating from Active Monitor, all new process PID are opened by me.

Catalina takes ram quickly and more than High Sierra and Mojave for same apps. and with a few apps, Catalina could reach 32GB ram easily. for those Macbook pro with 8GB or 16GB ram, it would be nightmare slow.

that is why I raise discussion here to see how many people see that Catalina eat ram quickly.
 
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gilby101

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ewu said:
both iMac and MBP 16inch have 64GB ram.

I open same projects in vscode, same java projects in same version of eclipse and run an ubuntu vmware configured to take 4GB ram, a simple docker container.

High Sierra takes 20GB ram
Catalina takes almost 30GB ram
Click to expand...

Or you could say (and it is equally valid):
High Sierra fails to use 44GB RAM
Catalina fails to use 34GB

So that is a win for Catalina!
 
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twintin

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Aug 10, 2012
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ewu said:
Catalina takes ram quickly and more than High Sierra and Mojave for same apps. and with a few apps, Catalina could reach 32GB ram easily. for those Macbook pro with 8GB or 16GB ram, it would be nightmare slow.
Click to expand...

Not at all. I'm running Catalina both on an Air 2012 and Air 2020 with 8 GB with no speed issues at all. I think you my have misinterpreted what the values you see actually mean in really life.
 
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saudor

macrumors 68000
Jul 18, 2011
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edubfromktown said:
What does memory pressure show in Activity Monitor?

If you are not seeing red and/or a lot of yellow in the graph, nothing to lose sleep over.
Click to expand...

I wonder how much of this is actually true. Personally i've never seen mine turn yellow/red no matter how many files open. The swap file will just keep growing like crazy instead but it never turns yellow/red.

I was also looking into my friend's 8gb RAM macbook pro last night. She had a million chrome tabs open. Chrome alone was using insane amounts of RAM and the SSD was working full time thrashing 5TB+ writes and using a 9gb+ swap file. CPU load was low but the computer was extremely slow. Switching between apps was a complete disaster

Memory pressure was all green and only like 3/4 of the way.
 
ewu

ewu

macrumors regular
Original poster
Apr 14, 2020
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I do more testing

1. start High Sierra and Catalina without doing anything, record ram usage of each system.
High Sierra uses 5.5GB ram and Catalina uses 6.0GB ram.

2. open a few apps randomly, such as docker/vmware/eclipse/vscode/oracle/mysql/posgresql and so on,
make sure High Sierra takes 32GB ram and Catalina takes 32GB ram

3. start to close all apps that opened.

I find that High Sierra could return back to 7GB ram after all apps are closed. comparing to 5.5GB initial ram usage, 7GB is acceptable.
However, Catalina only return back to 13GB ram. comparing to 6.0GB initial ram usage.
13GB is kind of "memory-leak" behaviour.
 
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evec

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Jun 8, 2016
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The Memory is not leaking, it just modern OS work mechanism.

Modern OS like Catalina fully use of large system memory for boost of speed.
As currently sandbox and auto release technology, program exits don't require real clear all program.
The program data and resources will remain on the memory if memory pressure low.

Just thing about:

SSD/HD = bookshelf
Memory = table
CPU Cache = hand

Size of memory = table area

It also have DMA mean CPU with Assistant for take/put book from table to bookshelf.

Free memory = table empty

Table empty don't mean the efficiency good, it just mean nothing.

So, OS will not need clear the memory when the memory no mandatory hold, it just need mark the region "can be cover".

For example, the Browser data will not delete if unless the memory not enough, so next time the user open the some Browser, the program code and data such as picture can be load instead, without need access the SSD, it just like another cache.

Although in real world, the tidy table will get better efficiency for human, for computer that almost zero advantage.
 
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gilby101

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ewu said:
Activity Monitor, one of mac os system's default apps.
Click to expand...

Thanks for clearing that up. Often, people describe everything except free memory as memory used.

If you want to diagnose the difference further you will need to collect a bit more than just that one number. At minimum, the other numbers in Activity Monitor - App memory, wired, compressed, cache, and (by subtraction) free. I am assuming that in both Macs you have zero swap.

When looking at individual processes (in Activity Monitor) you should view more columns than just 'memory' column.

You could write a script to track virtual memory behaviour over time based on the vm_stat command.

Understanding what is happening, in any detail, is very obscure - and this in spite of reading Jonathan Levin's books (which I can thoroughly recommend) http://newosxbook.com/index.php

Nevertheless, my view is that using (however that is measured) more of your 64GB is a good thing and so there has been an improvement in memory usage for you. I would only start to be concerned if there was significantly different swap usage.
 
ewu

ewu

macrumors regular
Original poster
Apr 14, 2020
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I update to 10.15.5 yesterday.

10.15.5 RAM management improves a little bit.

when I open a few apps to consume 32GB ram and close them all, it returns back to 8.5GB ram.

comparing to 13GB or 16GB before, it is better improvement.
 
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ewu

ewu

macrumors regular
Original poster
Apr 14, 2020
113
74
gilby101 said:
Thanks for clearing that up. Often, people describe everything except free memory as memory used.

If you want to diagnose the difference further you will need to collect a bit more than just that one number. At minimum, the other numbers in Activity Monitor - App memory, wired, compressed, cache, and (by subtraction) free. I am assuming that in both Macs you have zero swap.

When looking at individual processes (in Activity Monitor) you should view more columns than just 'memory' column.

You could write a script to track virtual memory behaviour over time based on the vm_stat command.

Understanding what is happening, in any detail, is very obscure - and this in spite of reading Jonathan Levin's books (which I can thoroughly recommend) http://newosxbook.com/index.php

Nevertheless, my view is that using (however that is measured) more of your 64GB is a good thing and so there has been an improvement in memory usage for you. I would only start to be concerned if there was significantly different swap usage.
Click to expand...

correct, 10.15.4 Catalina take zero swap since I only use half of physical ram to do test.

and 10.15.4 behaviour like memory-leak to me.

so far no matter what parameters I could see in Catalina related with ram, it is more than High Sierra and Mojave.
Catalina takes more ram resources, it makes sense that new OS take more ram resources, but it looks like that catalina doesn't release resources after it takes. 10.15.5 works better in ram management.

I hope I don't have to use kernel source code to prove that it is actually take more ram.
github.com

GitHub - apple/darwin-xnu: Legacy mirror of Darwin Kernel. Replaced by https://github.com/apple-oss-distributions/xnu

Legacy mirror of Darwin Kernel. Replaced by https://github.com/apple-oss-distributions/xnu - apple/darwin-xnu
github.com github.com
 
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timidpimpin

timidpimpin

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The more RAM you have, and the newer your OS, the more RAM it will use. Would you rather your RAM just sit there unused? It's using all that RAM to help make your system faster.
 
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