> Disabling swap on servers is de-facto standard for serious deployments.

I guess I have not been deploying seriously over the last couple of decades because the (hardware) systems that I deploy all had some swap, even if it was only a file.

What's your swappiness ?

Swap always seemed more meant for desktop use. Servers you need to give the real memory expected of the application stack.

Pretty much all the guidelines about swap partitions out there reference old allocator behaviour from way over a decade ago - where you'd indeed typically run into weird issues without having a swap partition, even if you had enough RAM.

Short (and inaccurate) summary was that it'd try to use some swap even if it didn't need it yet, which made sense in the world of enough memory being too expensive, and got fixed at the cost of making the allocator way more complicated when we started having enough memory in most cases.

Nowadays typically you don't need swap unless you work on a product with some constraints, in which case you'd hand tune low memory performance anyway. Just don't buy anything with less than 32GB, and you should be good.

plenty of footguns in that general advice, local in memory storage services with default config, etc

So the ideal behaviour would be:

  - for most processes no SWAP
  - for tmpfs, use RAM until a quota
  - for tmpfs, start using a swapfile above that quota

ChatGPT doesn't think it is achievable, though it thinks cgroup2 can achieve something similar.