Variations on fair I/O schedulers

Err, but there's been, like, astonishingly huge amounts of CPU scheduler innovation in Linux? Hacking the source is not really harder than implementing a stable API, you just lose other conveniences like choosing which scheduler at run time.

And in-fighting wouldn't be reduced; it would just shift to fighting over which scheduler got to be the Default, instead of which got to be the One And Only. If anything that would just make things worse, because you'd make it easier for the competing camps to co-exist over a long period and get Bitter, instead of pushing them to come to a resolution one way or another and combine efforts.