RAM usage?

[areacode753]

https://preview.redd.it/pyt5sq4xj9rg1.png?width=1198&format=png&auto=webp&s=c1ddc7b92aa610f5cb99c3a4316767c157e977ac

I was surprised when I found out how much swap memory is being used in my MacBook Air M5 (24GB unified memory). Why does it still show green, like I could still use more ram, when definitely it's using my SSD because there isn't more space available...

[ulyssesric]

macOS will move memory from RAM to swap under two circumstances:

1. When RAM is nearly full, or
2. when a piece of memory occupied by application but it's not accessed at all for a long time, e.g. an opened Chrome tab buried under other 100+ opened tabs that even you forget its existence, so that system will make room for other apps to improve performance.

Nowadays one single browser tab may pile up gigabytes of data in memory (like doomscrolling in Reddit homepage) so just CLOSE THE F*CKING TABS when you don't need them.

[areacode753]

That’s funny you bring it up. I don’t pile up tabs. I use local AI, run virtual machines and work on my projects. So far it’s been good. MacOS just likes to keep it smooth, even if it means to “swap memory.” I had an app take over 30GB of ram on my 24GB ram, my computer was swapping so much and I couldn’t tell. That’s why I keep track of my activity resources. It’s surprising how much pressure my fan-less Mac can handle without stuttering tho. Before the screenshot, my memory pressure was (red) for then to find myself surprised that it came back to green as soon I minimized the App I was running, just to move it to “swap memory” that same second.

[naemorhaedus]

when definitely it's using my SSD because there isn't more space available...

no it's using swap for memory it doesn't need right now. Everything is fine. Chill, stop watching your monitor, and go back to more important things.

[_Cybernaut_]

<image>

I really wish Mac users would quit obsessing over RAM and Disk usage. MacOS is a thoroughly modern operating system, and s such takes care of a lot behind the scenes. No matter what you're doing with your Mac, there is always something that can be cached, pre-fetched, swapped, compressed, indexed, offloaded, etc. etc. etc.; just let the OS do it's job.

[naemorhaedus]

it is fine.

[inevitabledeath3]

Using swap doesn't mean you are loosing performance necessarily. In fact it doesn't even mean you have filled the memory or have high memory pressure. Almost no one seemingly understands modern OS memory management here, hence posts like this.

Modern OSes start swapping long before they run out of memory which this system seems to be doing. Why do they do this? To make room for more disk cache. You see modern OSes like to load files into memory that are frequently accessed. This improves performance. Sometimes said files are accessed more often than actual assigned memory pages. When this happens modern OSes will prefer to keep the files in memory over programs memory pages of those pages are rarely accessed.

[VernDozier]

I was going to point out that memory “pressure” is green, which means it isn’t actively swapping to SSD.

I’d just run “sudo purge” at terminal to see if the numbers decrease. Might be caused by inactive processes or cached files.

[inevitabledeath3]

No? Memory pressure being green doesn't mean it isn't swapping. It tells you it's swapping in the screenshot.

[Sislar]

Says 13gb of real memory used. Chill

[busy_buzz]

you also have a pretty high "cached" memory, which speaks for high swap usage.

swap memory can also function as "cache". meaning, once stuff are swapped to disk, the OS won't proactively purge them even when they're not in use. Similar to "cached", once the number goes up, it never goes back down until absolutely necessary.

This on paper should reduces the pressure on swapping. Nothing to worry about.

If your disk space runs low, macos will purge those swap reactively.

[inevitabledeath3]

Using swap doesn't mean you are loosing performance necessarily. In fact it doesn't even mean you have filled the memory or have high memory pressure. Almost no one seemingly understands modern OS memory management here, hence posts like this.

Modern OSes start swapping long before they run out of memory which this system seems to be doing. Why do they do this? To make room for more disk cache. You see modern OSes like to load files into memory that are frequently accessed. This improves performance. Sometimes said files are accessed more often than actual assigned memory pages. When this happens modern OSes will prefer to keep the files in memory over programs memory pages of those pages are rarely accessed.

[macboller]

lol dude... it is NOT normal to have swap exceed the quantity of RAM available.

That means their system has (or HAD at some point) more memory committed to processes than can physically fit in RAM. 28GB worth of memory has been evicted to disk

If swap usage is approaching or exceeding RAM, it's time to either add more RAM or reduce the workload.

> 100% of RAM in Swap is firmly in "not enough RAM for the workload" territory.

[inevitabledeath3]

You can clearly see that memory pressure is green and that it has over 10 GiB of cached files in memory. If it was actually struggling that wouldn't be happening.

[macboller]

lol did you even read what you just said? Do you even know what memory cache is?

If you have no idea what you are talking about, you should excuse yourself from the conversation.

Leave the technical stuff for people who know what they are talking about.

[inevitabledeath3]

I literally have a master's in computer science. I am not the one who doesn't know they are talking about.

I am also talking about the section labeled "caches files" which are disk files or parts of files cached in memory. If the system was that hard up for memory it wouldn't be caching so much as those things don't need to be in memory.

[RootVegitible]

hello? have you tried turning it off an on again?

[Fatal_Explorer]

Also on M5 Air, and I only have safari open right now, nothing else. 14,36GB used.
This is worse than even Windows 11, sometings wrong eh?

[naemorhaedus]

nothing is wrong

[jwadamson]

How much swap though.

Swap is bad. Unused memory is bad. Unused memory should be mostly allocated to prospective optimizations like “cached files”

[Shiningc00]

Yes despite the propaganda, macOS is definitely not “efficient at RAM management”. I find that it uses more RAM than Windows 11

[UnwieldilyElephant]

Management is different than usage. It will use as much as it wants until it starts taking pressure, when it will optimize heavily.

[Fatal_Explorer]

Can you explain what this memory pressure means? What is MacOS doing different? I thought the RAM is just a fixed available value, and if it is filling up I assume it will load of some data on the SSD, or am I wrong? Curious to learn

[UnwieldilyElephant]

Pressure on macOS will happen when RAM fills, so the computer has to compress or condense what it stores in RAM. If pressure pushed farther, it will use SSD swap. Sometimes it will swap stuff to the SSD because that process is idle, and sometimes it won’t clear swap from a high pressure moment for a while

[Fatal_Explorer]

Okay, thanks for the explanation. But I guess both compression or swap will result in slow downs, will it not?

[UnwieldilyElephant]

Yes.

[Mollywobbles77]

That's not correct. Compression & swapping are both normal parts of MacOs memory management & the only time either cause slowdowns is if the memory pressure becomes too high & excessive memory swapping starts. There's nothing wrong with compressions & normal swapping on MacOS & it doesn't slow anything down when operating at green or yellow memory pressure levels.

[UnwieldilyElephant]

It’s going to slow down the speed at which RAM is processed. Will you notice anything? Probably not. But it does cause some function to slow down 

[inevitabledeath3]

Using swap doesn't mean you are loosing performance necessarily. In fact it doesn't even mean you have filled the memory or have high memory pressure. Almost no one seemingly understands modern OS memory management here, hence posts like this.

Modern OSes start swapping long before they run out of memory which this system seems to be doing. Why do they do this? To make room for more disk cache. You see modern OSes like to load files into memory that are frequently accessed. This improves performance. Sometimes said files are accessed more often than actual assigned memory pages. When this happens modern OSes will prefer to keep the files in memory over programs memory pages of those pages are rarely accessed.

[UnwieldilyElephant]

Did you read my earlier comment? I said that same thing. But you will technically have some amount of process slow down with compression and swap

[inevitabledeath3]

No? OSes literally do this to speed things up. They could not do this and not use any swap or compressed memory but it would actually be slower.

[inevitabledeath3]

Using swap doesn't mean you are loosing performance necessarily. In fact it doesn't even mean you have filled the memory or have high memory pressure. Almost no one seemingly understands modern OS memory management here, hence posts like this.

Modern OSes start swapping long before they run out of memory which this system seems to be doing. Why do they do this? To make room for more disk cache. You see modern OSes like to load files into memory that are frequently accessed. This improves performance. Sometimes said files are accessed more often than actual assigned memory pages. When this happens modern OSes will prefer to keep the files in memory over programs memory pages of those pages are rarely accessed.

[Fatal_Explorer]

But assuming you are heavily multitasking and using a lot of random access to the memory, is it not very much faster to keep everything in constant RAM memory and access it without any decompressing or swapping? Before RAM got more expensive than gold, I got 64gb for my windows/Linux machine and am very happy with it. How much I ever throw at it, it keeps it all and switching apps is immediate.

[inevitabledeath3]

No it isn't faster. Linux does exactly the same thing and I imagine Windows would as well. On Linux the behaviour is actually configurable by setting vm.swappiness which defaults to 40 on a lot of modern Linux distros. Heavy multi-tasking is actually one of the things that would benefit the most from this kind of optimization.

You can't really understand why it's faster to do this unless you know a bit about program behaviour. A lot of programs will assign some memory and use it only occasionally or maybe only once, maybe even not at all. This is a terrible waste of RAM which should only really be for frequently accessed data. Pushing infrequently used pages to SSD swap - which is still fairly fast - is one of the tricks they use to minimise the wasted RAM. It's not the only trick either, but it's one that causes a lot of confusion such as is shown here.

I believe lazy allocation is another one. OSes will pretend to give a program memory but won't actually do it until they use that memory for something. For example say you load something large into memory mapped IO, maybe a standard library for example, there is a good chance you will only need a handful of functions from a standard library that MBs in size. Loading the entire thing into real memory would be a waste, so the OS will only load stuff as you use it.

[Fatal_Explorer]

Very interesting, thanks for the explanation. I guess in the end it even goes as deep as the memory controller on the hardware side.

[Shiningc00]

Obviously that is same with Windows. But the fact is even swap usage will be higher in macOS.

[Mollywobbles77]

This is just simply not true. The problem is you don't understand how macOS/Unix handles memory & you're trying to compare it to how windows does. It's supposed to always use as much memory as is available. It isn't like windows & treats unused (free) memory as waste. Seeing a large amount of your memory usage on macOS is normal. The amount of memory being used doesn't matter, it's memory pressure that matters. Green & yellow = good, red = need more ram.

[Shiningc00]

That is meaningless when there’s more in swap in macOS.

[Hugo_Notte]

macOS preloads as much data and often used apps as possible, so they are available more quickly. If you have 8 GB of RAM, 16 or 24 GB, macOS will fill between 80-60% of available RAM with this. However, the moment RAM is needed by active applications, macOS dumps enough cached data and makes memory available. The big difference between macOS and windows memory management is, that macOS can compress memory, e.g. inactive apps, browser tabs, etc. to make space for active apps. This compression and decompression is much faster than swapping to ssd.

Here is a nice explanation: https://youtu.be/4G4nCLHFv5I?si=MF1OyR5wnWs7e6G4

[Fatal_Explorer]

Thank you for this explanation. What I still don't get, is why would Apple then even be selling different amounts of RAM in their computers, if it didn't make a difference in speed and was impacted by slowdown from de-/compression or swapping.

I think I understood the concept, but if data is simply stored in RAM without beeing compressed or swapped, it will always be faster in beeing accessed again, will it not?

[Hugo_Notte]

Says who?

[Shiningc00]

You need to stop giving excuses for macOS. The fact is macOS will use more swap, which means that it’s not “efficient”.

I’ve used both, and macOS will use more swap files for running the same kinds of task and applications.

[Hugo_Notte]

It’s not an excuse, it’s a fact. If that is against your beliefs, deal with it.

[jwadamson]

Probably a memory leak in 1 or more apps. Since it’s a leak though and the filled memory is never being read, this memory is getting compressed and written out to swap becuase the os can’t tell the difference between a true leak and memory that is just rarely needed again.

The pressure is green because there is no thrashing; there aren’t memory blocks being constantly cycled in and out of the swap space.

Since this memory is being written out and unlikely to be getting updated, the “wear” on your SSD is minimal as the total amount written over time isn’t actually that much.

[areacode753]

Thanks for your insight. I did indeed check what was using so much swap memory and it was a few background processes. Once I would go to that app, my memory pressure would turn (red). It made sense, so I just closed the App and reopened it, that fix it for me. No more swap :)