OS-CPU scheduling

"Define CPU scheduling."

"CPU scheduling is the process of determining which of the processes in the ready queue should be allocated CPU time."

"Explain the main objective of CPU scheduling."

"The main goal of CPU scheduling is to maximize CPU utilization and efficiency."

"Describe CPU-bound processes."

"CPU-bound processes are those that require significant CPU time and have long CPU bursts."

"What characterizes I/O-bound processes?"

"I/O-bound processes are characterized by spending more time waiting for I/O operations and having short CPU bursts."

"How does multiprogramming enhance CPU utilization?"

"Multiprogramming enhances CPU utilization by running multiple processes and switching among them, ensuring the CPU is effectively utilized."

"Describe the First Come First Served (FCFS) scheduling algorithm."

"FCFS schedules processes in the order of their arrival and is non-preemptive, using a FIFO queue for implementation."

"Explain the concept of a Gantt chart in CPU scheduling."

"A Gantt chart is a visual representation of process scheduling that illustrates the execution order and timing of processes."

"What are the drawbacks of the FCFS scheduling algorithm?"

"Drawbacks of FCFS include poor waiting time, turnaround time, and response time."

"How is average waiting time calculated in FCFS scheduling?"

"Average waiting time in FCFS scheduling can be computed based on the sequence of arrivals of the processes."

"Define Shortest Job First (SJF) scheduling."

"SJF scheduling allocates CPU time based on the length of the next CPU burst of jobs, aiming to minimize average waiting and turnaround times."

"What are the characteristics of SJF scheduling?"

"SJF can be non-preemptive or preemptive (Shortest Remaining Time First) and is optimal for minimizing average waiting and turnaround times."

"What challenge is associated with SJF scheduling?"

"The challenge associated with SJF scheduling is estimating the length of the next CPU burst."

"Describe the mechanism of priority scheduling."

"In priority scheduling, each process is assigned a priority number, and processes are scheduled based on their priority."

"Describe the difference between preemptive and non-preemptive scheduling."

"Preemptive scheduling allows the operating system to interrupt a currently running process to start or resume another process, while non-preemptive scheduling does not allow this interruption, meaning a process must run to completion before another can start."

"Explain how aging can mitigate starvation in scheduling."

"Aging is a technique used in scheduling to gradually increase the priority of lower priority processes over time, helping to ensure that they eventually get CPU time and do not suffer from starvation."

"Define Round Robin (RR) scheduling."

"Round Robin scheduling is a process scheduling algorithm where each process is assigned a fixed time slice or quantum, ensuring that all processes receive an equal share of CPU time."

"How does the size of the time quantum affect Round Robin scheduling performance?"

"The size of the time quantum in Round Robin scheduling significantly influences performance; a smaller quantum can lead to more context switching and overhead, while a larger quantum may reduce responsiveness."

"Explain the characteristics of Multilevel Queue Scheduling."

"Multilevel Queue Scheduling divides processes into different queues based on their priorities, with each queue potentially using its own scheduling algorithm, but it can lead to starvation and inefficiency if not managed properly."

"Describe the mechanism of Multilevel Feedback Queue Scheduling."

"Multilevel Feedback Queue Scheduling allows processes to move between different queues based on their behavior and requirements, adapting to the needs of the processes dynamically."

"What are the design considerations for Multilevel Feedback Queue Scheduling?"

"Key design considerations include the number of queues, the scheduling algorithms used for each queue, and the criteria for upgrading or demoting processes between queues."

"Define Guaranteed Scheduling and its application."

"Guaranteed Scheduling is a mechanism that ensures a certain level of CPU time for processes, making it particularly useful in environments where performance guarantees are critical."

"Differentiate between hard real-time and soft real-time scheduling."

"Hard real-time scheduling requires strict adherence to deadlines, essential for systems like embedded devices, while soft real-time scheduling allows some flexibility in meeting deadlines, suitable for applications like multimedia."

"Explain the difference between user-level threads and kernel-level threads."

"User-level threads are managed by thread libraries in user space, providing flexibility and efficiency, while kernel-level threads are managed by the operating system kernel, offering better integration with system resources."

"Describe the difference between Process Contention Scope (PCS) and System Contention Scope (SCS) in scheduling."

"PCS focuses on scheduling within a process, while SCS deals with scheduling across the entire system."

"Explain the significance of CPU Utilization in scheduling criteria."

"CPU Utilization measures the percentage of time the CPU is actively working, indicating how effectively resources are being used."

"Define Throughput in the context of scheduling."

"Throughput refers to the number of processes completed in a given time unit, reflecting the efficiency of the scheduling algorithm."

"How is Turnaround Time calculated in process scheduling?"

"Turnaround Time is the total time taken from the submission of a process to its completion."

"What does Waiting Time represent in scheduling metrics?"

"Waiting Time is the total duration a process spends in the ready queue before it begins execution."

"Describe Response Time in the context of process scheduling."

"Response Time is the interval from the submission of a process to the first response it receives."

"Explain the Deterministic Model used in evaluating scheduling algorithms."

"The Deterministic Model assesses performance based on predetermined workloads, making it simple yet specific."

"What is the Queuing Model in scheduling evaluation?"

"The Queuing Model uses Little's formula to calculate average wait times for processes."

"How do simulations contribute to the evaluation of scheduling algorithms?"

"Simulations predict performance under various loads, providing insights but are complex and resource-intensive."

"Describe the importance of implementation in evaluating scheduling algorithms."

"Implementation tests an algorithm's real-world effectiveness by coding it within an operating system."

"Explain the evolution of Linux scheduling from version 2.2 to 2.6.23."

"Linux scheduling evolved with version 2.2 introducing priority-based algorithms, 2.5 enhancing efficiency with O(1) scheduling, and 2.6.23 adding the Completely Fair Scheduler (CFS)."

"What are the characteristics of the Completely Fair Scheduler (CFS) in Linux?"

"CFS allocates CPU time proportionally based on the priority of tasks, aiming for fairness in resource distribution."

"How can FCFS Average Time Calculation demonstrate performance differences?"

"By analyzing different arrival orders, FCFS Average Time Calculation can reveal variations in performance outcomes."

"Describe how SJF Average Waiting and Turnaround Time can be modeled."

"SJF can be modeled for both preemptive and non-preemptive scenarios to compare their effectiveness in managing waiting times and turnaround."