CPU scheduling: what is the strategy called when the operating system temporarily suspends logically runnable processes to allocate CPU time fairly or meet responsiveness goals?

Difficulty: Easy

Correct Answer: preemptive scheduling

Explanation:


Introduction / Context:
Schedulers decide which process runs on the CPU at a given moment. Systems that must remain responsive or share the CPU among many tasks often interrupt a running process and switch to another ready process. Understanding this policy is critical for real time design, interactive systems, and general purpose OS behavior.


Given Data / Assumptions:

  • Processes are logically runnable, meaning they are in the ready state.
  • The OS may suspend a running process before it blocks or finishes.
  • We need the term for this class of scheduling policies.


Concept / Approach:

Preemptive scheduling allows the OS to interrupt and switch out a running task, giving the CPU to another ready task. Time slicing and priority based preemption are common mechanisms. Non preemptive policies let a process run until it voluntarily yields, blocks, or completes, which can hurt responsiveness.


Step-by-Step Solution:

Identify the behavior: a runnable process is temporarily suspended by the scheduler.Map to terminology: this is preemption; the OS preempts the current task.Note examples: round robin, priority preemptive scheduling.Conclude that the correct label is preemptive scheduling.


Verification / Alternative check:

Classic OS textbooks describe Unix like and modern Windows schedulers as preemptive, using time quanta and priorities to interrupt running processes.


Why Other Options Are Wrong:

  • non preemptive: the opposite behavior; no forced suspension.
  • shortest job first / first come first served: specific algorithms; SJF can be either, but the described suspension is characteristic of preemption.


Common Pitfalls:

  • Assuming preemptive implies unfairness; in fact, it enables fairness and responsiveness when correctly tuned.


Final Answer:

preemptive scheduling.

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