Scheduling policy behavior: Which scheduling approach permits temporarily suspending a currently runnable process so another process can run (i.e., supports preemption)?

Introduction / Context:
Schedulers arbitrate CPU time among runnable tasks. A key distinction is whether a running task can be involuntarily paused to allow another task to run. This is essential for responsiveness in interactive systems and for meeting deadlines in real-time systems.

Given Data / Assumptions:

• Multiple runnable tasks compete for a single CPU.
• We seek a policy that allows interruption of the current task.
• Alternative policies may require the running task to yield or finish its CPU burst.

Concept / Approach:

Preemptive scheduling allows the OS to interrupt and context-switch from the running task, e.g., at timer interrupts or priority changes. Non-preemptive scheduling (cooperative) waits for the running task to relinquish the CPU. FIFO/FCFS are typically non-preemptive queue disciplines that do not forcibly suspend a running task.

Step-by-Step Solution:

Verification / Alternative check:

Classic algorithms like Round Robin and Priority Preemptive are explicitly preemptive, supporting timer-based context switches for fairness and responsiveness.

Why Other Options Are Wrong:

• non-preemptive scheduling: Does not allow involuntary suspension.
• FIFO / FCFS: Typically non-preemptive; once running, a job continues until completion or blocking.
• None of the above: Incorrect because preemptive scheduling fits exactly.

Common Pitfalls:

Assuming FCFS implies preemption; confusing time slicing (preemption) with cooperative yields; ignoring interrupt-driven timer ticks enabling preemption.

Final Answer:

preemptive scheduling