CPU Scheduling Criteria
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Questions and Answers

What does CPU utilization measure?

  • Number of tasks completed within a specific period
  • System performance and productivity
  • Efficiency of memory usage
  • Percentage of time the CPU is busy processing a task (correct)

    • Why is it important to maximize CPU utilization?

  • To waste useful work
  • To reduce system resources
  • To increase system slowdown
  • To ensure the CPU is busy and working efficiently (correct)

    • What can high CPU utilization lead to?

  • Excessive competition for resources (correct)
  • Minimal tasks processed
  • Improved system performance
  • Decreased productivity

    • How is throughput defined in CPU scheduling?

    <p>The number of tasks or processes completed within a specific period</p> Signup and view all the answers

    Why is maximizing throughput important in batch processing environments?

    <p>To complete as many jobs as possible within a specific time frame</p> Signup and view all the answers

    What does a high throughput indicate about the system?

    <p>System is processing tasks efficiently</p> Signup and view all the answers

    In what scenario can too high CPU utilization lead to a system slowdown?

    <p>When there is excessive competition for resources</p> Signup and view all the answers

    Which criterion reflects the efficiency and productivity of the system?

    <p>Throughput</p> Signup and view all the answers

    How does maximizing throughput impact system performance?

    <p>It improves system performance and increases productivity</p> Signup and view all the answers

    What happens if the CPU is idle most of the time?

    <p>Decreased system productivity</p> Signup and view all the answers

    What is the purpose of minimizing turnaround time in CPU scheduling?

    <p>To improve user satisfaction and system efficiency</p> Signup and view all the answers

    Which CPU scheduling algorithm prioritizes turnaround time by focusing on short and simple tasks?

    <p>Shortest Job First (SJF)</p> Signup and view all the answers

    Why is minimizing waiting time important in CPU scheduling?

    <p>To reflect the efficiency of the scheduling algorithm</p> Signup and view all the answers

    Which CPU scheduling algorithm prioritizes waiting time by giving higher priority to more important tasks?

    <p>Priority Scheduling</p> Signup and view all the answers

    What is the significance of minimizing response time in CPU scheduling?

    <p>To ensure effective task processing</p> Signup and view all the answers

    Which CPU scheduling algorithm targets response time by prioritizing tasks that require immediate attention?

    <p>Round Robin</p> Signup and view all the answers

    In what type of systems is Round Robin scheduling algorithm effective?

    <p>Time-sharing systems</p> Signup and view all the answers

    "Choosing the right algorithm for a particular situation is critical for maximizing what in CPU scheduling?"

    <p>Both user satisfaction and system efficiency</p> Signup and view all the answers

    Why is prioritizing factors like turnaround time, waiting time, and response time essential in CPU scheduling algorithms?

    <p>To optimize system performance and user satisfaction</p> Signup and view all the answers

    Which of the following statements about minimizing waiting time in CPU scheduling is true?

    <p>Short waiting times lead to improved user satisfaction.</p> Signup and view all the answers

    What is the main task of a Long-Term Scheduler?

    <p>Selecting jobs from the pool and maintaining them in the ready queue</p> Signup and view all the answers

    Which objective is NOT typically associated with process scheduling?

    <p>Minimizing response time</p> Signup and view all the answers

    In a system with distinct policies for each queue, what task does the OS scheduler perform?

    <p>Moving tasks between the ready and run queues</p> Signup and view all the answers

    What role does a Short-Term Scheduler play in process scheduling?

    <p>Deciding which process to run next</p> Signup and view all the answers

    Which type of scheduler focuses on selecting processes from secondary memory and maintaining them in primary memory's ready queue?

    <p>Long-Term Scheduler</p> Signup and view all the answers

    Which criterion in CPU scheduling measures the time it takes for a task to complete from the moment it is submitted to the system until it is fully processed and ready for output?

    <p>Turnaround Time</p> Signup and view all the answers

    Which algorithm is NOT mentioned as prioritizing response time in CPU scheduling?

    <p>Shortest Job First (SJF)</p> Signup and view all the answers

    Why is minimizing waiting time important in CPU scheduling?

    <p>It reflects the efficiency of the scheduling algorithm.</p> Signup and view all the answers

    Which scenario can lead to a system slowdown due to CPU utilization?

    <p>High CPU utilization</p> Signup and view all the answers

    What is the main objective of prioritizing factors like turnaround time, waiting time, and response time in CPU scheduling algorithms?

    <p>To improve user satisfaction and productivity</p> Signup and view all the answers

    What is the primary role of the Long-Term scheduler in an operating system?

    <p>Controlling the degree of multiprogramming</p> Signup and view all the answers

    Which scheduler is responsible for reducing the degree of multiprogramming in the system?

    <p>Medium-Term Scheduler</p> Signup and view all the answers

    In CPU scheduling, what happens if the Short-Term scheduler makes a mistake and selects a job with a long CPU burst time?

    <p>All subsequent jobs will have to wait in a ready queue for a long period</p> Signup and view all the answers

    Which criterion is reflected in CPU scheduling algorithms that prioritize turnaround time?

    <p>Predictability</p> Signup and view all the answers

    What is the primary function of the Medium-Term Scheduler in an operating system?

    <p>Removing processes from memory and handling swapped out-processes</p> Signup and view all the answers

    What type of scheduling algorithm is FCFS?

    <p>Non-preemptive</p> Signup and view all the answers

    What scheduling algorithm is known for the Convoy effect?

    <p>Priority Scheduling</p> Signup and view all the answers

    What is the primary difference between non-preemptive SJN and preemptive SJN scheduling algorithms?

    <p>Burst time selection</p> Signup and view all the answers

    What is a characteristic of SJN scheduling?

    <p>Involves breaking ties using FCFS scheduling</p> Signup and view all the answers

    Why is FCFS scheduling not considered very efficient?

    <p>It doesn't prioritize important tasks</p> Signup and view all the answers

    Which scheduling algorithm is most likely to result in the lowest average waiting time?

    <p>Shortest Remaining Time First</p> Signup and view all the answers

    In Priority Scheduling, what happens when a higher priority task arrives while a lower priority task is being executed?

    <p>The lower priority task is paused until the higher priority task completes</p> Signup and view all the answers

    What is a significant disadvantage of the Round Robin scheduling algorithm?

    <p>It causes excessive context switching</p> Signup and view all the answers

    Why is the Starvation Problem a notable concern in Priority Scheduling?

    <p>It causes longer waiting times for certain processes</p> Signup and view all the answers

    Which CPU scheduling algorithm introduces the concept of preemptive execution based on process priorities?

    <p>Shortest Remaining Time First</p> Signup and view all the answers

    What is the primary goal of multilevel queue scheduling in operating systems?

    <p>To efficiently handle different types of processes based on their characteristics</p> Signup and view all the answers

    In multilevel queue scheduling, which type of processes are typically given the highest priority?

    <p>System processes</p> Signup and view all the answers

    Which queue in the multilevel queue architecture is used for non-interactive processes that take longer to complete?

    <p>Background queue</p> Signup and view all the answers

    How are processes sorted in multilevel queue scheduling?

    <p>By deadlines, priority, and I/O demands</p> Signup and view all the answers

    Which type of queue in multilevel queue scheduling includes system processes like device drivers and interrupt handlers?

    <p>System queue</p> Signup and view all the answers

    What is one of the challenges associated with implementing multilevel queue scheduling?

    <p>Preventing system instability due to improper design</p> Signup and view all the answers

    What is a potential issue that could arise if a process is continuously assigned to a lower-priority queue in multilevel feedback queue scheduling (MLFQ)?

    <p>Starvation where the process never gets to run</p> Signup and view all the answers

    Why is it essential to choose the appropriate scheduling algorithm for each queue in multilevel feedback queue scheduling (MLFQ)?

    <p>To prevent system instability and subpar performance</p> Signup and view all the answers

    In multilevel feedback queue scheduling (MLFQ), how does the system prioritize processes based on their performance?

    <p>By adjusting priorities dynamically according to performance</p> Signup and view all the answers

    What advantage does multilevel queue scheduling provide in distributing resources efficiently?

    <p>Ensuring crucial tasks are executed first based on their importance</p> Signup and view all the answers

    What is a major advantage of using MLFQ scheduling in real-time systems?

    <p>Ensuring tasks complete within a specific time frame</p> Signup and view all the answers

    Why is MLFQ scheduling considered to optimize CPU utilization effectively?

    <p>By prioritizing tasks based on their behavior</p> Signup and view all the answers

    What is a key disadvantage associated with MLFQ scheduling in terms of system predictability?

    <p>Poor predictability</p> Signup and view all the answers

    How does MLFQ scheduling address the issue of priority inversion?

    <p>By allowing lower-priority processes to hold resources</p> Signup and view all the answers

    Which aspect of MLFQ scheduling contributes to its complexity in implementation?

    <p>Maintaining multiple queues with different priorities</p> Signup and view all the answers

    Study Notes

    CPU Utilization and Scheduling

    • CPU utilization measures the percentage of time a CPU spends on executing instructions.
    • High CPU utilization can lead to increased throughput, but excessive utilization can cause slowdowns.

    Throughput and Performance

    • Throughput is defined as the number of tasks completed per unit time in CPU scheduling.
    • Maximizing throughput is crucial in batch processing environments to increase productivity.
    • High throughput indicates a system can handle more tasks efficiently.
    • However, too high CPU utilization can lead to system slowdowns.

    CPU Scheduling Algorithms

    • The criterion that reflects the efficiency and productivity of the system is throughput.
    • Maximizing throughput impacts system performance by increasing task completion rates.
    • Round Robin scheduling is effective in systems with time-sharing or interactive environments.

    Process Scheduling

    • The main task of a Long-Term Scheduler is to select processes from secondary memory and maintain them in primary memory's ready queue.
    • A Short-Term Scheduler plays a crucial role in process scheduling by selecting processes from the ready queue and allocating the CPU.
    • The OS scheduler performs the task of allocating the CPU to processes in a system with distinct policies for each queue.

    Scheduling Objectives

    • The primary objective of prioritizing factors like turnaround time, waiting time, and response time is to maximize system efficiency and productivity.
    • Minimizing waiting time is essential to prevent starvation and ensure fairness in CPU scheduling algorithms.

    CPU Scheduling Criteria

    • Turnaround time measures the time from task submission to completion.
    • Response time measures the time from task submission to first response.
    • Waiting time measures the time a task spends waiting in the ready queue.

    Scheduling Algorithms

    • FCFS (First-Come-First-Served) is a non-preemptive scheduling algorithm where tasks are executed in the order they arrive.
    • SJN (Shortest Job Next) is a scheduling algorithm that prioritizes short tasks to minimize waiting time.
    • Priority Scheduling is a preemptive scheduling algorithm that prioritizes tasks based on their priority.
    • Round Robin is a time-quantum-based scheduling algorithm that allocates a fixed time slice to each task.
    • Multilevel Feedback Queue (MLFQ) is a scheduling algorithm that uses multiple queues with different time slices to prioritize tasks based on their performance.

    Multilevel Feedback Queue Scheduling

    • Multilevel queue scheduling prioritizes processes based on their performance and allocates resources efficiently.
    • The primary goal of multilevel queue scheduling is to distribute resources efficiently among different types of processes.
    • System processes like device drivers and interrupt handlers are typically given the highest priority in multilevel queue scheduling.

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    Description

    Learn about the criteria for CPU scheduling, focusing on CPU utilization. Understand the importance of maximizing CPU utilization for efficient system performance and productivity.

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