There are good use cases for swap. I work with very performance sensitive memory hogging applications that tend to process in bursts as incoming batched data arrives. We also have a lot of required background "security" applications.

Having the idle applications move out to swap so that a significant amount of free RAM to allow for the active, real-time applications to expand into is a major boon. RAM is expensive now, so it's become even more critical to not waste it.

But even in self-hosting at home I take advantage of it since I have a limited number of servers with limited RAM and a bunch of applications and/or docker containers running, many of which don't need to be active at all times, but if they were all active, would have trouble with the limited RAM. Swap allows for inactive applications to free up RAM for the active ones and leave enough available at all times to allow an application to quickly spin up new jobs.

Anyway, sure, for a simple desktop computer without a bunch of junk background applications running for "security" or whatever, and an overabundance of RAM installed, it's probably not useful. But for high performance, memory hungry applications with lots of background stuff running, it can be a big help.

That said, there are use cases where the opposite is useful and using a RAM drive is better than writing to disk for cache and temporary logs when you have enough RAM. My opnsense router for instance uses a RAM drive to store cache and logs (logs are mirrored to the NAS for long term storage, so just the local copy is lost on reboot). That system has enough RAM and I'd rather reduce disk wear, and I don't plan to add too many other applications to that server that it would run low.

I used to be this guy. We have huge amount of memory in our storage server. Why would we need swap? Well, once the system started killing programs I read up on swap and how the system handles its caches, especially ZFS ARC.

Short version is that while the system can evict its caches syncronously, it can only async notify ZFS that it should also shrink its caches, but the out-of-memory killer will start killing before ZFS and its kernel counterpart can start to free up memory.

A tiny bit of swap completely solved this, since swapping is sync for the kernel and the OOM killer will wait for it.

No

It turns out the computer mostly freezes once you go past 200% RAM used.

All I know is that I had 16GB RAM and 4GB swap and I used to get crashes sometimes.

Set that fucker to 32GB out of spite, now no crashes. No idea why that helped. But I guess I do have like 15 tabs open on the regular (web dev)

"Unresizeable block device at end of disk"

Classically the swap partition was located at the physical middle of the drive so that on average, no matter where the heads where, the swap partition wasn't far away

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

People still use swap partitions instead of swap files?

swapfile gang

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

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.

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

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

Building a PC in 2026 be like "I cant afford RAM, but I can use a whole TB hard disk I shucked from an old WD external as swap and maybe my PC will feel modern"

I basically never used swap until I used some script that was supposed to de-duplicate text messages from SMS backups.

Turns out feeding it a 100,000 message archive spanning back 15 years will somehow eat up ~80GB of RAM. I doubt it should, I guess it probably just wasn't optimized for such a large amount.

So I made a 64GB swap file and it completed fine.

"Hello I would like to torture my SSD's FTL because I left three Electron apps open"

If you don't actually need the swap, Linux isn't going to make use of swap. If you need the swap, then you'd probably rather use it than have the OOM killer take out a process.

My desktop has plenty of swap available, but is using none of it, because the system isn't under memory pressure.

I init a ramdisk and put a swap file there and call it L4 cache

Definitely configure swap, but I don't think there is much benefit of a swap partition over a swap file these days and swap files are trivial to configure.

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

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...

Then what is the setup if my computer only has 4GB of memory for daily driving? Just curious because swap partitions are what I normally do on limited resource machines.

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

ACPI S4 Hibernation would like to have a word with you

Have a PC with 16gb ram that lives up to the overwatch game system reqs. When I installed it and launched it, it began building some sort of cache. A one time job. During that chache my os would force close steam to prevent an oom crash. I then added 16gb swap and during the owerwatch cache job the used phys ram would max out at 12gb I think and the swap sent up to 10gb. So a 22gb ram job. Yikes. Thanks swap ram 👍

I've had my computer crash trying to open or save a pdf once because it used up all the RAM space (16gb) and then used up the small swap (probably like 10gb?) and I guess some critical processes I guess just got told "no." Seems wild to me that Windows would just crash before it told a pdf it couldn't use over 20gb of memory.

I have a small home server that I occasionally push through huge batch processing jobs. During the pushes, I might collide with other projects that use a pretty big chunk of the RAM. So, to make sure it's never a killer (just a major slow down), I made a 32GB swap file. If I need it, it's there and disk is hella cheap.

This machine has never had a GUI installed. No browsers to complain about, just plain old data processing, stats models, and old skool computing.

Now, my worst case scenario was building a C++ program on a raspberry pi gen 1. That has 256MB of RAM. g++ ran out building, so I NFS mounted a huge disk from my desktop machine and made the swap file there. The build took a while... but the program ran fine after the week long build, no swap needed.

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.

The trick is to first create a RAM disk. Then put the swap file on there and it's about as fast as RAM. Then, with the new memory you have created, make another RAM disk. Yep, then make more swap space on there.

I have solved both the memory and SSD availability issues with this infinite RAM and disk space trick.

ZFS chuckles darkly in the corner

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.