Round Robin scheduling in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Time Quantum in Round Robin Scheduling

In Round Robin scheduling, what is the main role of the time quantum (time slice)?

A It determines how long a process can run before the CPU switches to the next process.

B It sets the total time a process can run until it finishes.

C It prioritizes processes based on their arrival time.

D It decides the order in which processes are added to the queue.

💡 Hint

Think about how Round Robin shares CPU time fairly among processes.

The time quantum is the fixed amount of time each process gets to use the CPU before the scheduler moves to the next process in the queue.

📋 Factual

intermediate

Effect of Time Quantum Size on Round Robin Performance

What happens if the time quantum in Round Robin scheduling is set too large?

A All processes finish at the same time regardless of their burst time.

B The system behaves like First-Come, First-Served scheduling, causing longer wait times for some processes.

C Processes switch too quickly, increasing overhead and reducing CPU efficiency.

D The scheduler ignores the time quantum and runs processes randomly.

💡 Hint

Consider what happens when the time slice is very long compared to process burst times.

If the time quantum is very large, each process runs almost to completion before switching, making Round Robin behave like First-Come, First-Served, which can increase waiting time for other processes.

🔍 Analysis

advanced

Calculating Waiting Time in Round Robin Scheduling

Given three processes with burst times 5, 3, and 8 units respectively, and a time quantum of 2 units, what is the total waiting time for all processes?

A 10 units

B 13 units

C 17 units

D 21 units

💡 Hint

Simulate the process execution in rounds, subtracting burst times and tracking waiting times.

By simulating the Round Robin execution with time quantum 2, the total waiting time sums to 21 units.

❓ Comparison

advanced

Comparing Round Robin and Shortest Job First Scheduling

Which of the following statements correctly compares Round Robin (RR) and Shortest Job First (SJF) scheduling?

A RR schedules processes based on priority, while SJF uses arrival time.

B RR always results in lower average waiting time than SJF.

C RR is preemptive and fair to all processes, while SJF is non-preemptive and favors shorter processes.

D SJF is preemptive and guarantees no starvation, unlike RR.

💡 Hint

Think about how each algorithm treats process length and fairness.

Round Robin gives each process equal CPU time in turns (preemptive and fair), while SJF selects the shortest process next and can be non-preemptive, potentially causing longer processes to wait.

❓ Reasoning

expert

Identifying the Impact of Context Switching Overhead in Round Robin

In a Round Robin system with a very small time quantum, what is the most significant impact of frequent context switching on overall system performance?

A Increased CPU overhead reduces the time available for actual process execution.

B Processes complete faster because they get more frequent CPU access.

C Memory usage decreases as processes are swapped out quickly.

D The system becomes more energy efficient due to shorter process runs.

💡 Hint

Consider what happens when the CPU spends more time switching than running processes.

Frequent context switches consume CPU time and resources, reducing the time available for running processes and lowering overall efficiency.