etw.h is generated from etw.man which contains the manifest for mimalloc events. (100 is an allocation, 101 is for a free)

etw-mimalloc.wprp is a profile for the Windows Performance Recorder (WPR). In an admin prompt, you can use:

> wpr -start src\prim\windows\etw-mimalloc.wprp -filemode
> <my mimalloc program>
> wpr -stop test.etl

and then open test.etl in the Windows Performance Analyzer (WPA).