The extensible scheduler class

> Honestly: this line makes me think linux should try to take a stab at the whole M:N scheduling thing again (which AFAIK no implementations, on any OS/kernel, have been successful/performant thus far). With a (small) M:N syscall interface, you could have a scheduling user-space "process". That process should be a realtime scheduled, and then you get the full power of a plug-able scheduler AND the ability to write it in any language you have a runtime/compiler for.

Google Fibers is an M:N in-process scheduling framework that has been used internally at Google for 10+ years, quite successfully. There have been several attempts to upstream the kernel side of it (UMCG, FUTEX_SWAP).