The CPU scheduler’s one job at any given time is to run the task that has
the strongest claim to the CPU. There are many factors that complicate
that job, not the least of which is that the “strongest claim” is sometimes
a bit of a fuzzy concept. Realtime throttling, a mechanism designed to
keep a runaway realtime task from monopolizing the CPU, is one case where
developers have concluded that the task with, ostensibly, the highest
priority should not actually be the one that runs. But realtime throttling
has rarely pleased anybody; the deadline-server
infrastructure patches posted by Daniel Bristot de Oliveira are the
latest attempt to find a better solution.

Source: LWN.net – [$] Deadline servers as a realtime throttling replacement