real time scheduling in Linux

Question

This morning I read about Linux real time scheduling. As per the book \'Linux system programming by Robert Love\', there are two main scheduling there. One is SCHED_FIFO, fi

Answer 1

My understanding of the two different classes is that a process SCHED_FIFO is never pre-empted by the kernel. Even if another "SCHED_FIFO" class process is waiting its turn...

While SCHED_RR policy shares the cpu ressources a little bit more. The scheduler will let the SCHED_RR process run for a quanta of time, then pre-empt it only to let turn another SCHED_RR process. That is exactly Round Robin.

SCHED_FIFO is "stronger" in the sense that if a SCHED_FIFO process never yield() to the kernel or invoke a system call on a single core device, then all your other Real time processes may never run.