Podcast
Questions and Answers
Shortest Job First (SJF) is primarily utilized for long term scheduling.
Shortest Job First (SJF) is primarily utilized for long term scheduling.
False (B)
The Longest Job First (LJF) scheduling process is based on the shortest burst time.
The Longest Job First (LJF) scheduling process is based on the shortest burst time.
False (B)
Starvation is a disadvantage associated with the Shortest Job First scheduling algorithm.
Starvation is a disadvantage associated with the Shortest Job First scheduling algorithm.
True (A)
Highest Response Ratio Next (HRRN) scheduling algorithm selects processes based solely on their burst time.
Highest Response Ratio Next (HRRN) scheduling algorithm selects processes based solely on their burst time.
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Longest Job First (LJF) scheduling can lead to a high average waiting time.
Longest Job First (LJF) scheduling can lead to a high average waiting time.
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CPU scheduling is used to determine which task or program does not get to use the CPU at a particular time.
CPU scheduling is used to determine which task or program does not get to use the CPU at a particular time.
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In Multiprogramming, selecting multiple I/O bound processes may keep the CPU idle.
In Multiprogramming, selecting multiple I/O bound processes may keep the CPU idle.
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The Waiting Time is calculated by subtracting Burst Time from Turn Around Time.
The Waiting Time is calculated by subtracting Burst Time from Turn Around Time.
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First Come First Serve (FCFS) is highly efficient and recommended for all scheduling situations.
First Come First Serve (FCFS) is highly efficient and recommended for all scheduling situations.
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Shortest Job First (SJF) scheduling method can be either non-preemptive or preemptive.
Shortest Job First (SJF) scheduling method can be either non-preemptive or preemptive.
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Turn Around Time is the time difference between arrival time and completion time.
Turn Around Time is the time difference between arrival time and completion time.
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Preemptive Scheduling occurs when a process switches from ready state to running state.
Preemptive Scheduling occurs when a process switches from ready state to running state.
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The average waiting time in Shortest Job First (SJF) scheduling is typically lower than in First Come First Serve (FCFS) scheduling.
The average waiting time in Shortest Job First (SJF) scheduling is typically lower than in First Come First Serve (FCFS) scheduling.
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Study Notes
Operating Systems - Part IV: Scheduling Algorithms
- CPU scheduling is a process used by the operating system to determine which task or program gets to use the CPU at a specific time.
- Many programs can run simultaneously, necessitating CPU management to give each program fair access.
- CPU scheduling aims to make the system more efficient and faster.
CPU Scheduling
- The primary function of CPU scheduling is to keep the CPU occupied with a process whenever it's idle.
- In multiprogramming, if the long-term scheduler selects multiple I/O-bound processes, the CPU remains idle most of the time.
- Efficient program design aims to improve resource utilization.
Terminologies in CPU Scheduling
- Arrival Time: The time a process enters the ready queue.
- Completion Time: The time a process finishes execution.
- Burst Time: The time a process takes for CPU execution.
- Turnaround Time: The difference between completion time and arrival time (computation time).
- Waiting Time: The difference between turnaround time and burst time.
Types of CPU Scheduling Algorithms
- Preemptive Scheduling: A process switches from running to ready state or waiting to ready state.
- Non-Preemptive Scheduling: A process terminates or switches from running to waiting state.
Types of CPU Scheduling Algorithms
-
Preemptive:
- Priority Scheduling
- Shortest Remaining Job First
- Longest Remaining Job First
- Round Robin
- First Come First Serve
-
Non-Preemptive:
- Shortest Job First (SJF)
- Longest Job First (LJF)
- Highest Response Ratio Next (HRRN)
Non-Preemptive Scheduling - First Come First Serve (FCFS)
- Simplest Algorithm: Tasks are scheduled in the order they arrive (FIFO).
- Convoy Effect: Longer processes can block shorter processes from executing. This significantly increases the average waiting time.
Non-Preemptive Scheduling - Shortest Job First (SJF)
- Selects the waiting process with the shortest execution time next.
- Often reduces average waiting time significantly.
- Potential for starvation (a process might never get executed).
Non-Preemptive Scheduling - Longest Job First (LJF)
- Selects the process with the longest burst time to execute first.
- All processes finish approximately at the same time.
- High average waiting times; can lead to a convoy effect.
Non-Preemptive Scheduling - Highest Response Ratio Next (HRRN)
- Prioritizes processes with the highest response ratio.
- Response ratio = (waiting time + burst time) / burst time.
- Aims to mitigate starvation issues found in SJF, but still has potential for convoy effect in some cases.
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Description
Test your knowledge on various CPU scheduling algorithms, including Shortest Job First, Longest Job First, and First Come First Serve. This quiz covers concepts like waiting time, turn around time, and the effects of multiprogramming on CPU efficiency. Perfect for students studying operating systems and scheduling techniques.
