umorpha-boxes/NOTES.md

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# erofs compression
```bash
#!/bin/bash
set -x
# Algorithms are listed in erofs-utils:lib/compressor.c.
# The best level for each algorithm is listed in erofs-utils:lib/compressor_${alg}.c:.best_level.
choices=(
lz4 # doesn't take a level argument (.setlevel is NULL)
lz4hc,12 # /usr/include/lz4hc.h
lzma,109 # compressor_liblzma.c
deflate,9
libdeflate,12
)
time zstd mario.img # creates mario.img.zst
mkdir mnt
sudo mount -o loop mario.img mnt
for choice in "${choices[@]}"; do
time sudo mkfs.erofs -z"${choice}" mario-"${choice/,/-}.img" mnt
done
```
| 1.6G | mario.img | 1m7s | Non-compressed
|------+-------------------------+--------|
| 904M | mario.img.zst | 4s | For comparison
|------+-------------------------+--------|
| 1.2G | mario-lz4.img | 53s |
| 1.1G | mario-lz4hc-12.img | 2m18s |
| 957M | mario-lzma-109.img | 10m17s |
| 997M | mario-deflate-9.img | 2m25s |
| 0 | mario-libdeflate-12.img | - | (compiled without libdeflate support)