This is stuff. Some of it does things. Mostly just personal backup, but
hey if it's useful for you the files have licenses, knock yourself out.
If the files don't have licenses poke me and I'll fix that.

 alloca_games/
  - Did you know that alloca() and variable length arrays shouldn't be
    mixed when using gcc (and maybe others)? This tests what happens when
    you do.

 avl/
   - Ted Unangst wrote an avl tree implementation that never got used for
     whatever he wrote it for. I beat it up to make it smaller and faster
     and added an iterator to it.

 flippedarray/
   - Experiment to simulate the cache behavior of binary searching in an
     array when we apply a function to the array index. The theory is
     that if we reverse bits in the index (let's say the array has
     2^5 elements, the index 10100 would be mapped to 00101) the first
     few elements visited will be the first few elements of the array
     and thus always in the cache. The simulation looks promising, but
     this is completely unfinished.

 heap/
   - Binary heap with in-struct linkage along the same principles as
     sys/tree.h in OpenBSD.

 hello_elf_amd64_linux/
   - Experiement to see how small a proper hello world can be in a binary
     that runs on linux amd64 (ELF). 112 bytes. Considering that you need
     120 bytes of headers for an ELF binary with one load section, I'd say
     it can't be reduced anymore.

 linker_set/
   - FreeBSD style linker sets.

 lock_recursion_is_bad/
   - Favourite example for why lazily making your locks recursive is a
     bad idea. This is a bug that was present in many unix-like systems
     many years ago that made the filesystem leak uninitialized data.
     At the moment of writing this it will deadlock the process on
     macos and after a reboot the file will contain stuff from
     uninitialized memory (technically it contains unitialized memory
     before the reboot, but I haven't found a way to read it without
     deadlocking).

 totiming/
   - Experiments for measuring performance of different kern_timeout
     implementations.