Arch Linux

002

Member

Registered: 2025-10-03

Posts: 2

dm-encrypt performance

Hi, I use linux kernel with lvm on luks encryption, a week or two ago I notice worse performance to the point where system froze when writing or reading from disk.
I found this https://www.reddit.com/r/linux/comments … crypt_and/ post

cryptsetup --perf-no_read_workqueue --perf-no_write_workqueue --persistent refresh cryptdevice

This command managed to stop my system from freezing but performance is quite bad at 20MiB on a nvme.
I read that zen kernel mitigated this and I'm yet to try it but is there a way to improve performance without changing kernel?

EDIT: added cryptsetup bencmark

cryptsetup benchmark                                                                                                                                             
# Tests are approximate using memory only (no storage IO).
PBKDF2-sha1      3731587 iterations per second for 256-bit key
PBKDF2-sha256    6921293 iterations per second for 256-bit key
PBKDF2-sha512    2173214 iterations per second for 256-bit key
PBKDF2-ripemd160 1064544 iterations per second for 256-bit key
PBKDF2-whirlpool  787219 iterations per second for 256-bit key
argon2i      10 iterations, 1048576 memory, 4 parallel threads (CPUs) for 256-bit key (requested 2000 ms time)
argon2id     10 iterations, 1048576 memory, 4 parallel threads (CPUs) for 256-bit key (requested 2000 ms time)
#     Algorithm |       Key |      Encryption |      Decryption
        aes-cbc        128b      1140.6 MiB/s      2366.7 MiB/s
    serpent-cbc        128b       119.3 MiB/s       682.4 MiB/s
    twofish-cbc        128b       229.0 MiB/s       403.6 MiB/s
        aes-cbc        256b       898.4 MiB/s      2246.0 MiB/s
    serpent-cbc        256b       119.3 MiB/s       682.3 MiB/s
    twofish-cbc        256b       229.1 MiB/s       403.6 MiB/s
        aes-xts        256b      2896.2 MiB/s      2898.0 MiB/s
    serpent-xts        256b       606.5 MiB/s       596.8 MiB/s
    twofish-xts        256b       373.8 MiB/s       373.4 MiB/s
        aes-xts        512b      2622.8 MiB/s      2621.3 MiB/s
    serpent-xts        512b       607.0 MiB/s       597.8 MiB/s
    twofish-xts        512b       373.7 MiB/s       373.2 MiB/s

Last edited by 002 (2025-10-03 12:59:15)

c>rust

Member

Registered: 2025-09-07

Posts: 23

Re: dm-encrypt performance

it could be a filesystem problem

twelveeighty

Member

Registered: 2011-09-04

Posts: 1,447

Re: dm-encrypt performance

With problems like this it's usually not a good idea to just try random "solutions" unless you are sure of the root cause. Post `journalctl -b` from after a fresh reboot w/ logging in and waiting 2-3 minutes.

topcat01

Member

Registered: 2019-09-17

Posts: 277

Re: dm-encrypt performance

Make sure to also enable trim (disabled by default on LUKS) and then run fstrim. This is almost certainly not a LUKS issue; the performance impact (if any) is not really noticeable.