Scheduling criteria (turnaround time, waiting time, throughput) in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Turnaround Time

Which of the following best defines turnaround time in process scheduling?

A The number of processes completed per unit time.

B The time a process spends waiting in the ready queue.

C The time taken by the CPU to execute the process instructions.

D The total time taken from process submission to completion.

💡 Hint

Think about the entire duration a process is in the system.

Turnaround time measures the total time from when a process enters the system until it finishes execution, including waiting and running times.

🧠 Conceptual

intermediate

Waiting Time Explanation

What does waiting time represent in CPU scheduling?

A The time a process spends executing on the CPU.

B The time a process spends waiting in the ready queue before execution.

C The total time from process arrival to completion.

D The time taken to switch between processes.

💡 Hint

Consider the time before the process actually starts running.

Waiting time is the total time a process spends waiting in the ready queue before it gets CPU time.

🔍 Analysis

advanced

Calculating Throughput

Given 5 processes completed in 20 seconds total, what is the throughput?

A 0.25 processes per second

B 20 processes per second

C 5 processes per second

D 4 processes per second

💡 Hint

Throughput is the number of processes completed divided by total time.

Throughput = Number of processes completed / Total time = 5 / 20 = 0.25 processes per second.

❓ Comparison

advanced

Comparing Scheduling Criteria

Which scheduling criterion focuses on maximizing the number of processes completed in a given time?

A Throughput

B Waiting time

C Turnaround time

D Response time

💡 Hint

Think about the rate of process completion.

Throughput measures how many processes finish per unit time, so maximizing throughput means completing more processes quickly.

❓ Reasoning

expert

Impact of Scheduling on Waiting Time

Consider three processes with burst times 4, 3, and 2 units arriving at the same time. Which scheduling method will minimize the average waiting time?

A First-Come, First-Served (FCFS)

B Round Robin with quantum 1

C Shortest Job First (SJF)

D Priority Scheduling with arbitrary priorities

💡 Hint

Think about which method runs shorter processes first.

SJF schedules the shortest processes first, reducing waiting time for shorter jobs and minimizing average waiting time overall.