Question

In Operating Systems, which of the following CPU scheduling algorithms is strictly non-preemptive?

• A. Round Robin
• B. Shortest Remaining Time First
• C. First-Come, First-Served (FCFS)
• D. Priority Scheduling (Preemptive)

Hint:

Non-preemptive algorithms (like FCFS) are easier to implement and have less overhead, but they can suffer from the "Convoy Effect," where short processes wait behind a long process.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The goal is to pinpoint the CPU scheduling algorithm among the options that is strictly non-preemptive, meaning a running process cannot be interrupted before it voluntarily yields the CPU.


Step 2: Detailed Explanation:
Let's analyze each option:
- Round Robin (RR): This is a preemptive algorithm that relies on a fixed time quantum. Processes are interrupted if they exceed their time slice.
- Shortest Remaining Time First (SRTF): As the preemptive counterpart to Shortest Job First, it interrupts the current process if a newly arrived process has a shorter burst time.
- First-Come, First-Served (FCFS): This algorithm executes processes strictly in their arrival order. Once a process is allocated the CPU, it runs to completion or blocks on its own. Hence, it is strictly non-preemptive.
- Priority Scheduling (Preemptive): The option explicitly states it is preemptive, allowing higher-priority processes to interrupt lower-priority ones.
Consequently, FCFS is the only non-preemptive choice provided.


Step 3: Final Answer:
The correct choice is (C).