Generally it only happens to programs you keep running in the background and might not use for a long time that also don't have much background activity. For example password managers.

I do the same and use ugrd. I think dracut would also work.
You just set the resume kernel parameter to the decrypted memory device with the swapfile offset.
As long as the initrd attempts a resume after it decrypted all volumes it'll work, and the initrd doesn't even need to understand why and what was resumed from

btrfs's handling makes sense. The kernel talks to the disk directly, the file is just a pointer for what range it uses, and a placeholder for the filesystem. Something like raid, balancing, cow, all won't work because the kernel doesn't even go through btrfs to change the swap"file".
If you want a proper file as swapfile, with the corresponding overhead, you can make a regular file and mount it via loopback then use it as a swap device.

As well as oom situations, swapping allows the memory to be used more effectively by swapping out anonymous pages that aren't likely to be used but can't be dropped.

So you shut your pc down like a caveman when you do hardware upgrades or repairs or move apartments?

I don’t recall that, but IIRC it does need to be a minimum of installed RAM if you want to be able to hibernate, since then you write out the contents of your memory to swap.

IF RAM used + swap used don't exceed total swap space. Yeah, sometimes I run into that. Solved by killing webbrowsers, which suggests that most of the swap space is filled with unused webpages...

swapfile gang

.rw------- root root 4.0 GB Mon Jun  1 04:10:37 2026  /var/swap

what if you never restart the browser though?

Is this tongue in cheek i swear I cannot tell any longer.

Some swap is beneficial

It’s based on a common meme template. Yeah it’s tongue in cheek and I guess a lot of commenters can’t tell given this is a memes comm

64 GB are $1000 so maybe not

Yeah I shut down every day. It boots up fast enough that it's really not an issue.

It depends on what you set your swappiness to, too. I think Linux distros still have pretty aggressive defaults that swap more than they probably need to.

Do you hibernate? 🐻

And here I am using swap for my self hosted services, some of which use ridiculous amount of ram.

Everyone defending swap like crazy in the comments... so let me give a counter argument specifically for desktop:

Many years ago I stopped using swap on all my computers (I exclusively use linux) and the reason is: every time anything regarding interactivity went to swap, my system would freeze and literally become unusable for a really long time until I killed something. Since I got tired if that behaviour I decided I prefer for random shit to die but my computer still be usable.

It wasn't very often, but I don't get OOM killer often either (as in I don't remember the last time it happened and I use linux every day for both work and fun), and the freezing situation was way more annoying, to the point I sometimes ended up cold switching off the computer. I'm surprised on how many people run out of memory constantly. I guess you all are just using linux for servers and have crazy processing of infinite data...

Were you using a HDD for swap? It's nearly unnoticeable on an NVMe drive.

yep it was HDD, but with the low amount of times I have any OOM issue, I'm way more worried about NVMe flash burning than a random process being killed once every blue moon.

In fact I didn't mention, but since the advent of flash drives what I've done is trying to locate heavy disk writing apps and find alternatives for them, amid disabling many logs.

For swap, it hunts me to think some automatic process I don't have control over will burn those sweet erase cycles without me noticing just because someone programmed it poorly. I'm way more happy knowing I have some control over it.

"I'm not a friggin bear, I don't hibernate!"

My built-in Devil's Advocate has to ask if that's really true? Have you got a citation newer than 2 decades old? Frankly, i find it difficult to believe that anyone wouldn't like to use electron software, for the simple reason that making your SSD suffer is fun.

Edit: in 30 years of administering Linux and (previously) Solaris sytems i've never once had to change HDDs or SSDs, so claims of torture are, i opine, exaggerated. i'll also claim that keeping electron software out of the filesystem is not good for your hygiene.

what is using so much ram?

Swap and zram saved my R and Python Dana analysis script a couple of times.

No, I have a 13-second boot time

Trying to ray-trace a 512,000x256,000 image using Chunky. I had to split it into 16 parts to reduce the RAM to a sane amount (in 2018, it may have been optimised since).

I was trying to find the limit for a single png, and I think I found it.

I sometimes cannot do hibernate when I did a scrub on my ZFS. But the first try always frees up the swap and so the second attempts works every time.

I close my browser before hibernating; more lifetime for my SSD that way and it is faster, too.

I use 1.5-2x the swap on new installations these days. I want hibernate to always work.

I use the same, but I think to be super conservative It should be 1.5x + VRAM

16GB are my usual breakfast, I'll fill that quickly after booting... I'm happy that I got 64GB, though even that is often used up, thus I sometimes wish for 128Gb though (and for running somewhat capable local LLMs 512GB would be even better...).

Bottomline: ypu can basically never have enough RAM...

That makes it funnier ngl

I'd guess that there are probably utilities to export the world file to POV-Ray or Blender or something. They might be able to scale better.

That’s some really great luck you have, over the 15 years or so I have been running my Linux server I have had to replace the SSD twice(likely due to gentoo and compiling everything all the time) and had 2 hdds in my raid cluster need replacement. Here’s hoping my NAS has your luck

To be clear: what i wrote is not actually something real, it was a joke i made by modifying a comment from a thread on github gist, i am actually surprised it wad credible enough that someone would reply seriously xD

https://gist.github.com/joshenders/c4960cec9c63a7b7d68ffa9543356c43

I manage a cluster that makes heavy use of SSDs in RAID10 configuration. Those things are constantly degrading and having to be swapped out. I've started a drawer of faulted drives that I don't have the heart you throw out.

Bah, 56 seconds ought to be enough for anyone

I found that with swap the applications would slow to a crawl and then basically lock up entirely until I hauled my ass over and manually power cycled the machine.

Once tortured myself with having to go through...

The Android build system. Booo, scary.

I only wanted a LineageOS boot image built. The recommended specs list 64GiB RAM. Figured wouldn't apply to me until I tried to build a target literally called "nothing". It just used up all of the RAM and OOMed about 2 minutes in, building the "build cache" or whatever the fuck it needs to do to "warm up".

After a few fucktons of swapspace, turning off some of my daemons, some sysctl fuckery (there were options for limiting process virtual memory size IIRC? I put it all the way up) and taskset -p 0-15:1 (use logical CPUs 0, 2, 4...), I had my laptop allocating 50 something GiB. I have 16GB (decimal) physical RAM installed and I consider that already way too much for my usual needs.

After about half an hour of the build system build systeming, it just stopped doing that then built the kernel in 4 minutes with everything else in some time too.

Yes, I have tried just running make directly. That just resulted in an image that did nothing but toggle on and off an empty (no percentage) charging circle via power button.

Also "unresizeable" as if you can't just swapoff and just delete and recreated it anywhere (update the path in fstab) and then swapon again.

I don't really need swap until I need to compile blender... Need somewhere around 64Gb (with compression) to deal with the peaks

That is pretty cool. Did not know that. Will still be keeping my partition because it works fine for me.

Like a lot of memes, they exaggerate for humor. This meme was originally about math.

Or shotcut. I once ran it on 8GB, minimal arch with no swap. Well.

And I'm not even trying to build android on my new relatively modern laptop. It won't work.

Definitely bit the onion on this one, it did seem remarkable lol though I just pulled a 16 year old drive out of my Son’s PC(that was technically still working however slowly) hence the semi plausibility on my end lol

Also, while Linux does run without Swap, it's like running gears without grease.

lmao, 16 years is a lot! That drive can drive

Been using a swap file in a luks partition for years. I hibernate very regularly.

unfortunately with S0ix being forced on all modern laptops, zram is the only logical choice. With s3 sleep at least i can say i need swap because i need hibernation...With S0ix? Dont bother.

Can anyone tell me why I see swap usage with 10+GB of free RAM available?

SWAP RAM is useful for hibernation mode and fall back ram incase you have low memory.

Because you just taught your computer how to be lazy. "oH lOoK aT mE i'M sWaP mEmOrY"