Linux is an open source computer operating system created by Linus Thorvalds created in 1991. His Linux kernel has been used in several operating system projects usually called distributions. Famous distributions are Slackware, Debian and CentOS.
distributions
There is more to linux then Ubuntu or CentOS; here is a selection of for me interesting linux distributions.
articles on musl-libc
musl-libc, alpine’s greatest weakness
zram zstd
Enable zRAM for a more efficient swap system
https://docs.kernel.org/admin-guide/blockdev/zram.html
https://www.techrepublic.com/article/how-to-enable-the-zram-module-for-faster-swapping-on-linux/
https://www.maketecheasier.com/configure-zram-ubuntu/
https://wiki.gentoo.org/wiki/Zram
compressed filesystem
zfs zstd compression
btrfs zstd compression
schedulers
https://en.wikipedia.org/wiki/Completely_Fair_Scheduler
https://blog.maxgio.me/posts/linux-scheduler-journey/
https://www.geeksforgeeks.org/completely-fair-scheduler-cfs-and-brain-fuck-scheduler-bfs/
https://news.ycombinator.com/item?id=30209366
https://lwn.net/Articles/873244/
https://github.com/aliyun/plugsched
alternative directory structure
[Gobo](https://www.gobolinux.org/
linux on 8bit and 16bit architectures
[fuzix](https://github.com/EtchedPixels/FUZIX](https://www.fuzix.org/)
uzi, unix-like for the z80
elks, a 16bit no-mmu linux-like
different os setup
https://www.qubes-os.org/intro/
run linux on iphone/ipad at native speed https://worthdoingbadly.com/hv/