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Comment by Bender | Hacker News Reader

Which filesystem do you have on top of the encryption? If it's the default btrfs that might be one factor. Have you tested using ext4? What is the make/model of the physical storage?

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I tried it with BTRFS and had really terrible performance. I ended up trying ext4 and it was not appreciably better. I don't know the make and model of my SSD, but I'm sure it's a not-very-impressive SSD. Unencrypted with EXT4 was the only thing that offered good performance.

Mind you, I'm really happy with CachyOS, but I don't really understand why this is a problem and it doesn't seem to be an issue others are having.

Maybe this is something you have already checked but first get your device with blkid or whatever you prefer, then

    sudo smartctl -x /dev/nvmeXXXX

Look at the temperature when you are pushing the IO really hard. Some devices will throttle when hot.

Is this on a laptop? Do you have any indoor pets that have fur? Yaks shed a lot this time of year.

I'll check that out. In my case I had moved straight from Fedora and was using LUKS + EXT4 -- with no issues whatsoever. Further, rather than losing some write speed, my system will actually hang quite aggressively. It seems to be CPU-related, but perhaps it's disk reads that are hanging? (or maybe both) My PC case is also not extra-hairy :)

To benchmark the encryption if you suspect CPU related, try

    cryptsetup benchmark

though it's more useful if it was run prior on your previous OS installation. For storage, fio [1] may be useful but that is a much more involved topic and having baseline tests run in your former OS that you said worked fine.

[1] - https://fio.readthedocs.io/en/latest/fio_doc.html

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