preemptive

[shaharhada]

In the link:

C program for non-preemptive SJF CPU scheduling algorithm

Introduction to non-preemptive SJF scheduling : A different approach to CPU scheduling is the shortest-job-first(SJF)...

nitcselabprograms.blogspot.com

the author define non-preemtive executions as:
Non-preemptive execution means the execution of a process will not be deferred at any time.

O.K. I don't understand exactly the meaning of preemptive?
Can somebody write a definition of preemptive in this context?
Why the use the word preemptive? is it like precaution?

 

[Lafong]

I'd guess that "non-pre-emptive" is a near synonym for "non-pre-emptable" or "that which shall not be pre-empted".


I'm not a programmer, but found this; maybe you've already seen it:

Preemptive and Non-Preemptive Scheduling | Baeldung on Computer Science

Learn the differences between preemptive and non-preemptive scheduling techniques.

www.baeldung.com

Non-Preemptive Scheduling

This is the type of scheduling algorithm in which a process runs till it finishes or goes to the wait state. We can’t interrupt it while it’s running.

Examples of non-preemptive scheduling algorithms include the popular first-come-first-serve (FCFS), in which the order of execution is strictly based on the arrival time. As the name implies, the first to arrive is the first to be served.

Another example is the shortest-job-first (SJF) algorithm which gives priority to the process with the shortest time required for completion. Here, the shortest process runs to completion before the next shortest job takes over the CPU.

All non-preemptive scheduling algorithms follow the same pattern.

An example of a preemptive algorithm is Round-Robin. It gives all processes equal priority and assigns them equal time periods in a round or circular order, as the name implies. Another example is Shortest-Remaining-Time-First (SRTF), which gives priority to the process with the shortest time left to completion.