explain pre emptive and non preemptive scheduling?

Question

diff bet preemptive & nonpreemptive in os

Answer 1

@S.Archana

According to my old operating system concepts textbook (silberschatz, galvin, gagne) from a while ago, pg. 154, "under non-preemptive scheduling, once the CPU has been allocated to a process, the process keeps the CPU until it releases the CPU either by termination or by switching to the waiting state."

So I guess with that being said preemptive scheduling would likely be the opposite. Meaning that the CPU can be released from a process even if the process isn't complete.

For ex, the Round Robin (RR) scheduling algorithm is preemptive. If a process' CPU exceeds the allotted time burst allowed then that process is "preempted" and is put back on the ready queue while a different process is granted the CPU for a certain allotted time. And the same process continues for new process who was granted CPU time.

Hope that makes a little sense S. Archana