Linux real time scheduling (SCHED_FIFO and SCHED_RR) use a variation on this that approaches it from the other side.
Tasks in those two scheduling tasks will basically never be preempted by a lower priority task nor a task in any other scheduling class. However the system has an overall percentage limit on how much of the cpu tasks in these classes may consume. If they consume more than this limit, they will be preempted and non-RT tasks will run "for a while" before heading back to RT tasks.
Tasks in those two scheduling tasks will basically never be preempted by a lower priority task nor a task in any other scheduling class. However the system has an overall percentage limit on how much of the cpu tasks in these classes may consume. If they consume more than this limit, they will be preempted and non-RT tasks will run "for a while" before heading back to RT tasks.