Why does disc swap happen when there's plenty of free RAM?

[Queen6]

@madoka Close Activity Monitor and use the Mac as intended. As said swap is a complex subject as it could be driven by the OS an application or both. Swap wont slow your Mac down or burn out the SSD, nor any need to turn off swap via terminal.

13" Mac's I only purchase the base models one is over 8 years old and unsurprisingly the SSD is fine and it's been 80%-90% full for the vast majority of it's life. My 13" M1 MBP is again a base model that is used as needed. I dont worry about such nonsense.

Dont listen to the worry wardens. Yes SSD's can and do fail, however that's more likely due to a manufacturing defect than a factor of wear on a notebook. By the time the SSD is done your Mac will be well and truly obsolete.

I purchase base models as they serve purpose, save on cost, get the job done, dont need to mess with Apple with a BTO in the event of being DOA and is simply easier to sell and replace. Nor do I feel the need to add to Apple's coffers more than I need to.

Have to say; Mac's are fairly durable I've used mine in anger from the sub Artic to the equator. The 2014 13" MBP has been absolutely hammered and spent much of it's working life in the tropics. Similar with the M1 I just dont care about the SSD usage, I dont even look. Mac's are meant to be used and used hard, fragile they are not by any means...

Q-6

 

[compwiz1202]

It is normal. The same thing happened with my Mac mini that had 32 GB of RAM. Even Windows PC's do it. As to the technical details IDK but I suspect the programmers at Apple know more than me so I leave it alone.

Here is another thread with lots of replies so it might be helpful.

https://forums.macrumors.com/threads/swap-is-used-even-though-50-of-ram-is-still-free.2222254/

Yea I wondered this on PC. Don't know why, but some programs just "need" it. I would turn off swap, and the program would cry abouit VM, even with plenty of free physical RAM.

 

[Ethosik]

I get your point, and troubleshooting is valid. However, that does not nullify the Apple support/KB document, which does not address — no pun intended — the RAM usage cause/source. In other words, your scenario would err could still befit from more RAM as the article indicates, but with an indefinite ceiling.

You are saying I need more than 128GB of RAM because I hit a bug and got red memory pressure a few times? I’m only doing 1080p video editing. Something my 2010 Mac Pro with 8GB of RAM can accomplish with FCP.

 

[MacCheetah3]

You are saying I need more than 128GB of RAM because I hit a bug and got red memory pressure a few times?

Put simply, yes. However, of course, as you elaborated, there are more factors in play than what Activity Monitor analyzes. Thus, indeed, while the simple solution, more RAM wouldn’t be the optimal in your case.

Circling back, for the majority of users, Apple’s document (and memory pressure gauge) are satisfactory.

 

[Ethosik]

Put simply, yes. However, of course, as you elaborated, there are more factors in play than what Activity Monitor analyzes. Thus, indeed, while the simple solution, more RAM wouldn’t be the optimal in your case.

Circling back, for the majority of users, Apple’s document (and memory pressure gauge) are satisfactory.

How do we know the bug will be resolved if I even got 1TB of RAM? It’s a bug. It could just fill up the RAM no matter what I got.

 

[pshufd]

Can you find a version that predates the bug and use that? That's something that I'm doing right now with a piece of software. I found a bug, pulled the old version off of Time Machine, reported the bug and am using the old version.

 

[ArkSingularity]

Something to note about swap is that whenever Mac OS puts anything into swap, it won't bring it back into RAM until it's accessed (even if there is plenty of free RAM). If anything ends up pushing some pages out into swap and they aren't accessed for a long time, they will remain there for a while.

It's a little weird that they're being put into swap at all if the RAM usage is consistently low, but with only 60MB, it's swapping out stuff that is extremely infrequently accessed. It's not going to really put much wear and tear on the SSD, it more or less is just parking pages there. There won't be much of a performance hit until you start seeing MacOS swap out more actively used pages.

 

[WriteNow]

In very old MacOS versions, there used to be GUI to disable/enable it, and how much to reserve for it, but I think that went away with OSX.

I remember that. Part of the Control Panel. I generally had it off, since the machines I used that had this option were good enough that I didn't need virtual memory. Although a PowerBook 1400 I have as a toy does have virtual memory--but it won't let me turn it off, due to a mix of OS 9 and limited memory.

Other memory from that era: a setting to set how much memory would be reserved for a disk cache. And also the ability to create RAM disks.

 

[WriteNow]

I'm curious: what happens if you run out of RAM and you have swap disabled?

Don't know with the Mac--but I have seen Linux systems apparently completely lock up. Although that may not be universal to even Linux--it might hinge on the distro, software being used, etc.

 

[PauloSera]

Sure, average swap usage might lower your expected SSD life by a day or two… is it really something to worry about though?

😂 Thank you for that. I'm so tired of these people.

 

[WriteNow]

A cynic might say they want to use virtual memory heavily no matter what because it'll wear out the SSD faster. Which means you'll be buying a Mac sooner than you otherwise might.

 

[PauloSera]

Saying swap is bad for your SSD is like saying walking is bad for the bottom of your feet.

 

[theorist9]

Probably a brief spike in demand.

I suspect this as well--that the OP didn't actually have free RAM. I don't know whether MacOS puts data into swap when RAM is available but, IME, it does not. I used to have 32 GB on my iMac, and would occasionally see small amounts of swap following routine office use. However, after I upgraded it to 128 GB, I never saw anything in swap (unless I was specifically doing a task that required more than that amount of RAM).

I.e., if MacOS did use swap even when plenty of RAM was available, I would continue to see swap even after upgrading to 128 GB RAM. The fact that it stopped after the upgrade suggests it doesn't.

 

[pshufd]

I have 128 GB if RAM on my W10 box and I think that I set the pagefile size to 0 and disabled swap too. I have 32 GB of RAM on my Studio and MacBook Pro and there is rarely any swap. There was more in earlier versions of Monterey and Ventura, probably due to memory leaks but they've all been solved for what I do.

 

[Ethosik]

Can you find a version that predates the bug and use that? That's something that I'm doing right now with a piece of software. I found a bug, pulled the old version off of Time Machine, reported the bug and am using the old version.

It only happens in Davinci Resolve, and it happens on the older version too. It is some sort of issue with my source video files. Re-encoding them fixes it and now Davinci Resolve only uses 5GB of RAM. Final Cut Pro never had the issue and it too only used about 5 GB of RAM.

So I either re-encode the video or just use Final Cut Pro.

Just saying it's not always the case where red memory pressure means you need more RAM. I think anyone here would laugh if it was stated you need more than 128GB of RAM for basic 1080p video processing, especially when 90% of the time the applications are only using 5GB of RAM. There is no Apple Silicon Mac out yet with more than 128GB of RAM.

 

[pshufd]

It only happens in Davinci Resolve, and it happens on the older version too. It is some sort of issue with my source video files. Re-encoding them fixes it and now Davinci Resolve only uses 5GB of RAM. Final Cut Pro never had the issue and it too only used about 5 GB of RAM.

So I either re-encode the video or just use Final Cut Pro.

Just saying it's not always the case where red memory pressure means you need more RAM. I think anyone here would laugh if it was stated you need more than 128GB of RAM for basic 1080p video processing, especially when 90% of the time the applications are only using 5GB of RAM. There is no Apple Silicon Mac out yet with more than 128GB of RAM.

Glad you have a workaround. I've worked in software since 1979 and bugs are just part of the world. Ideally you just fix the bug and then provide a workaround to the customer so that they at least know that the problem will be resolved in a future version.

I'm also willing to use different software or even different hardware to try to work around problems. Customers shouldn't have to do this but it's the current state of the industry.

 

[Ethosik]

Glad you have a workaround. I've worked in software since 1979 and bugs are just part of the world. Ideally you just fix the bug and then provide a workaround to the customer so that they at least know that the problem will be resolved in a future version.

I'm also willing to use different software or even different hardware to try to work around problems. Customers shouldn't have to do this but it's the current state of the industry.

It was a very odd bug. It was processing just fine then got stuck part way through, my CPU spiked, memory just kept climbing until it hit 128GB then I got MASSIVE swapping like crazy. System became VERY slow. I had to force quit Davinci Resolve. Right click and force quit took literally a couple of minutes my system got that slow. Tried it again after a restart and some time, same thing happened. Then I just re-encoded my video using Adobe Media Encoder and loaded it up in Davinci Resolve and it processed just fine and only used 5GB of RAM. Very strange issue.

And I had zero effects, zero transitions, it was as basic editing as you can get. I just had to trim a portion out that is it!

I recently started giving Davinci Resolve a try so it's not a good first impression for me. Like I said even the raw video file worked just fine in Final Cut Pro and Media Encoder had no issues re-encoding it.

 

[yitwail]

For anyone still following the thread, I used to think that when swap takes place, it would write to a file in /private/var/vm but while Activity Monitor/iStat Menus shows swap use, the only file I see in
/private/var/vm is sleepimage. Have swapfiles been moved elsewhere?

 

[benwiggy]

No one has ever manually managed their memory more efficiently than the OS. Get on with your work. It's fine.

 

[Juicy Box]

No one has ever manually managed their memory more efficiently than the OS. Get on with your work. It's fine.

This isn’t accurate, especially with anyone manually managing memory after dealing with memory leak issues.

MacOS 10.9 had some bad memory leak issues.

That said, I think the issue that the OP is experiencing is probably normal.

 

[name99]

For anyone still following the thread, I used to think that when swap takes place, it would write to a file in /private/var/vm but while Activity Monitor/iStat Menus shows swap use, the only file I see in
/private/var/vm is sleepimage. Have swapfiles been moved elsewhere?

On APFS VM lives in a separate volume. This is feasible because APFS volumes have flexible size.

In terminal type: diskutil list
On my machine I see
#: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI EFI 314.6 MB disk0s1 2: Apple_APFS Container disk1 1.0 TB disk0s2 /dev/disk1 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +1.0 TB disk1 Physical Store disk0s2 1: APFS Volume iMac - Data 901.1 GB disk1s1 2: APFS Volume Preboot 1.8 GB disk1s2 3: APFS Volume Recovery 1.1 GB disk1s3 4: APFS Volume VM 5.4 GB disk1s4 5: APFS Volume iMac 8.9 GB disk1s5 6: APFS Snapshot com.apple.os.update-... 8.9 GB disk1s5s1
disk1s5 is the OS volume
disk1s1 is my data
disk1s2, 3, 4 are various utility partitions as per the names

 

[Juicy Box]

Saying swap is bad for your SSD is like saying walking is bad for the bottom of your feet.

Walking an excessive amount of time could be bad for the bottom of your feet.

This is especially an issue if the swap/walking is unnecessary.

 

[compwiz1202]

How do we know the bug will be resolved if I even got 1TB of RAM? It’s a bug. It could just fill up the RAM no matter what I got.

Is there any limit to RAM per process in MacOS? I remember a game I once played in Windows was 32-bit and leaked memory like sieve, so whenever it hit 2GB, CRASH

 

[satcomer]

I believe bad programing in some large programs! I've seem large audio daws make their app Universal while having their packing in Intel only unpackers! Plus don't getting going on popular plug-ins still Intel only, even on my friend video systems! it's like these plug-in companies are fly night operators that don't know just with half day programing could make a Universal version very easily sense you already make iOS version of the same plug-ins! To me this near criminal this time is change!

 

[name99]

Is there any limit to RAM per process in MacOS? I remember a game I once played in Windows was 32-bit and leaked memory like sieve, so whenever it hit 2GB, CRASH

There is no limit in macOS. Try "launchctl limit" to see some of the limits that do exist.
There is a limit on iOS, but you can go larger if you get a special entitlement.