Henrik mentioned the problem of patches for MariaDB that ignore the Windows platform. I am guilty of this as MySQL on Windows is irrelevant to me. I am not alone. What contributions do we get from the MySQL on Windows community in patches, performance tests or bug reports? I have never seen a benchmark result for MySQL on Windows.
There is nothing wrong with this. The relationship between users and vendors for MySQL on Windows is different. This is an opportunity for vendors (Sun/MySQL, Monty Program, Innobase/Oracle, Percona, Pythian, Open Query) to add value. I suspect that Sun/MySQL and Innobase/Oracle already care a lot about MySQL on Windows. But maybe they should offer a discount for MySQL on Linux users to offset our contributions (insert smiley face).
As an example of the value that can be added, I filed bug 46957 because InnoDB does not appear to support concurrent IO requests per file on Windows. That is, there can be either 1 pending read or 1 pending write to a file. That might hurt performance. I wrote about this in March and while there were assertions that this couldn't be the case I am not aware of any progress. The basis for my claim is from reading the source. Maybe someone who builds and/or runs MySQL on Windows can confirm or deny this.
If you want to learn more about systems programming on Windows, this is the book to buy. I have an earlier edition of it. One day I will read it. I tried to learn more about WriteFile, ReadFile and why win32/win64 don't support the equivalent of pread/pwrite by searching online for 'WriteFile API' and 'WriteFile API site:mysql.com'. The results were disappointing. Am I expected to buy a copy of the API docs?