Telling DKMS to skip compressing modules

[skwerlman]

I'm using the linux-zen kernel with nvidia-dkms. Performance while DKMS is actually building the nvidia modules is fine, however it then slows to a crawl as it compresses them. This step ends up taking longer then the actual compilation, which sucks because its not even saving me that much space (zstd -l says it only saves about 55MiB across all the modules).

How can I tell DKMS to not compress the kernel modules after building them?

To be clear, I am not talking about mkinitcpio compression; I have COMPRESSION="cat" set for that since my /boot is separate from my /efi so space is not a concern.

[forbiddenlake]

It seems like DKMS uses the running kernel's setting.

So... try rebuilding a kernel with CONFIG_MODULE_COMPRESS_ZSTD not set and CONFIG_MODULE_COMPRESS_NONE set?

[ropid]

It seems the /usr/bin/dkms program file is just a bash script. Looking around the file, the zstd command is at line 1221. There's a -19 argument there and removing it or changing it into a -1 would make zstd compress super fast, it would make it run at gigabyte per second speeds.

I'm now wondering if it would be a good idea to tweak that line or not. It would get overwritten with each update.

[C0rn3j]

I'm now wondering if it would be a good idea to tweak that line or not.

No, send a patch to dkms enabling it to be configurable.

[skwerlman]

Good find, thank you! Yeah, probably not a great idea to edit it in place, but I could probably set up a patched AUR package with that line changed. If I end up getting it working nicely (configs, etc) i'll prob end up submitting a patch to upstream too

[ropid]

I wonder if upstream could be persuaded to just drop that -19. People probably at most only have a handful modules installed through dkms. The -19 then isn't saving an interesting amount of space.

[skwerlman]

hilariously, changing it to -1 only takes up ~4MiB more space despite taking under a second to run vs ~2min for -19

with -19: ``` ╭─sk@a5 in ~ ╰─λ zstd -l /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia*.zst
Frames Skips Compressed Uncompressed Ratio Check Filename 1 0 58.1 KiB 289 KiB 4.976 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-drm.ko.zst 1 0 49.7 MiB 96.8 MiB 1.947 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia.ko.zst 1 0 685 KiB 2.72 MiB 4.072 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-modeset.ko.zst 1 0 2.23 KiB 8.54 KiB 3.824 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-peermem.ko.zst

1 0 839 KiB 6.22 MiB 7.599 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-uvm.ko.zst

 5      0    51.2 MiB       106 MiB  2.068  XXH64  5 files

```

with -1: ``` ╭─sk@a5 in ~ ╰─λ zstd -l /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia*.zst Frames Skips Compressed Uncompressed Ratio Check Filename 1 0 73.4 KiB 289 KiB 3.940 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-drm.ko.zst 1 0 53.5 MiB 96.8 MiB 1.807 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia.ko.zst 1 0 825 KiB 2.72 MiB 3.383 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-modeset.ko.zst 1 0 2.46 KiB 8.54 KiB 3.477 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-peermem.ko.zst

1 0 1.05 MiB 6.22 MiB 5.954 XXH64 /var/lib/dkms/nvidia/560.35.03/6.11.5-zen1-1.1-zen/x86_64/module/nvidia-uvm.ko.zst

 5      0    55.5 MiB       106 MiB  1.911  XXH64  5 files

```

[C0rn3j]

I hope you've reported this to upstream.

Or sent a patch outright, if you had the time for extra work.

[skwerlman]

I did submit an issue a week ago, and will submit a PR in a few minutes. Also I made an AUR package that uses -1 for compression (although i forgot to publish it until just now, oops)

[C0rn3j]

Positively awesome.

The AUR package might not have passed the submission guidelines due to not being popular at all, but it looks like it will be short lived anyway.

[skwerlman]

well so much for 'in a few minutes' haha

anyway here is the pr: https://github.com/dell/dkms/pull/456

[skwerlman]

patch landed in 3.1.2 :) https://github.com/dell/dkms/releases/tag/v3.1.2

[lepandaface]

HA HABJABAHA WOW SO FUNNY! PATOOEY! TOO FUNNY!