Hacker News Reader

Comment by david_allison | Hacker News Reader

My M1 MacBook is currently sitting at 46GB usage. It's not heavily under load

(WebStorm, Rider, Android Studio, Chrome, Discord & Slack), not currently running an Android Emulator, LLM or Docker

The OS will use more RAM if you give it more RAM. The fact that you are currently using 46GB on an (I assume) 64GB model doesn't necessarily mean that your workload would run badly on a 32GB or 16GB model.

It's more likely to mean exactly that, because the less RAM, the more disk swapping.

At some point it becomes impossible for the OS to keep everything it wants in RAM at the same time, and then you get an orgy of disk thrashing and a potential lock-up.

This is not theoretical. I've had it happen on both Macs and Windows machines, sometimes with just a single main app running.

At best you'll get obvious delays if you switch apps, as pages get dumped to disk while other pages are loaded.

Yes, you may get some swapping, but with a fast SSD that won't necessarily degrade performance too much.

Some RAM is used for file caching and other optional stuff, so not all of the additional usage will translate into swap if RAM is reduced.

MacOS also makes use of RAM compression, which increases the amount of memory pressure that can be sustained before swapping is necessary.

All in all, it's pretty complicated, and the only way to know if a workload will perform acceptably on a machine with less RAM is to try it.

Reply on news.ycombinator.com