CPU scheduling

This document summarizes key concepts from Chapter 5 of the textbook "Operating System Concepts - 8th Edition" regarding CPU scheduling. It introduces CPU scheduling as the basis for multiprogrammed operating systems. Various scheduling algorithms are described such as first-come first-served, shortest job first, priority scheduling, and round robin. Criteria for evaluating scheduling algorithms include CPU utilization, throughput, turnaround time, waiting time, and response time. Ready queues can be partitioned into multiple levels with different scheduling policies to implement multilevel queue and feedback queue scheduling.

1. Process management is an integral part of operating systems for allocating resources, enabling information sharing, and protecting processes. The OS maintains data structures describing each process's state and resource ownership. 2. Processes go through discrete states and events can cause state changes. Scheduling selects processes to run from ready, device, and job queues using algorithms like round robin, shortest job first, and priority scheduling. 3. CPU scheduling aims to maximize utilization and throughput while minimizing waiting times using criteria like response time, turnaround time, and fairness between processes.

The document discusses CPU scheduling in operating systems. It describes how the CPU scheduler selects processes that are ready to execute and allocates the CPU to one of them. The goals of CPU scheduling are to maximize CPU utilization, minimize waiting times and turnaround times. Common CPU scheduling algorithms discussed are first come first serve (FCFS), shortest job first (SJF), priority scheduling, and round robin scheduling. Multilevel queue scheduling is also mentioned. Examples are provided to illustrate how each algorithm works.

Gives an overview about Process, PCB, Process States, Process Operations, Scheduling, Schedulers, Interprocess communication, shared memory and message passing systems

The document discusses the Shortest Job First (SJF) CPU scheduling algorithm. SJF is a preemptive scheduling policy that selects the waiting process with the shortest execution time/burst time to execute next. The algorithm involves sorting processes by arrival time and selecting the process with the shortest burst time. An example shows the Gantt chart and calculations for average turnaround time and waiting time using SJF. Advantages include shorter jobs being favored and minimum average waiting time, while disadvantages are potential starvation of longer jobs and inability for short-term CPU scheduling.

Process scheduling involves assigning system resources like CPU time to processes. There are three levels of scheduling - long, medium, and short term. The goals of scheduling are to minimize turnaround time, waiting time, and response time for users while maximizing throughput, CPU utilization, and fairness for the system. Common scheduling algorithms include first come first served, priority scheduling, shortest job first, round robin, and multilevel queue scheduling. Newer algorithms like fair share scheduling and lottery scheduling aim to prevent starvation.

CPU scheduling more complex when multiple CPUs are available Homogeneous processors within a multiprocessor Asymmetric multiprocessing – only one processor accesses the system data structures, alleviating the need for data sharing Symmetric multiprocessing (SMP) – each processor is self-scheduling, all processes in common ready queue, or each has its own private queue of ready processes Currently, most common Processor affinity – process has affinity for processor on which it is currently running soft affinity hard affinity Variations including processor sets

Maximum CPU utilization obtained with multiprogramming CPU–I/O Burst Cycle – Process execution consists of a cycle of CPU execution and I/O wait CPU burst followed by I/O burst CPU burst distribution is of main concern

UNIT II PROCESS MANAGEMENT Processes-Process Concept, Process Scheduling, Operations on Processes, Interprocess Communication; Threads- Overview, Multicore Programming, Multithreading Models; Windows 7 - Thread and SMP Management. Process Synchronization - Critical Section Problem, Mutex Locks, Semophores, Monitors; CPU Scheduling and Deadlocks.

Round Robin is a preemptive scheduling algorithm where each process is allocated an equal time slot or time quantum to execute before being preempted. It is designed for time-sharing to ensure all processes are given a fair share of CPU time without starvation. The process is added to the back of the ready queue when its time slice expires. It provides low response time on average but increased context switching overhead compared to non-preemptive algorithms. The time quantum value impacts both processor utilization and response time.

First come first serve. A simple slide demonstration of FCFS regarding Operating System subject Computer Applications

This chapter discusses multithreaded programming and threads. It defines a thread as the basic unit of CPU utilization that allows multiple tasks to run concurrently within a process by sharing the process's resources. Different threading models like many-to-one, one-to-one, and many-to-many are described based on how user threads map to kernel threads. Common thread libraries for POSIX, Windows, and Java are also covered. The chapter examines issues in multithreaded programming and provides examples of how threads are implemented in Windows and Linux.

This document presents an overview of priority scheduling algorithms. It discusses basic concepts of scheduling, criteria like CPU utilization and turnaround time. It provides an example of priority scheduling with and without preemption. Advantages include ease of use and suitability for varying time requirements. A disadvantage is potential indefinite blocking of low priority processes.

This document discusses desktop systems and multiprocessor systems. For desktop systems, it describes them as personal computers dedicated to single users, with keyboards, mice, displays and small printers. It notes they run operating systems like Windows, MacOS, UNIX and Linux. For multiprocessor systems, it defines them as having multiple processors that share clocks, memory and buses. Symmetric multiprocessors have similar operating systems on each processor, while asymmetric ones have predefined master-slave roles. Multiprocessor systems provide advantages like reliability, throughput and cost-effectiveness, but require more memory, expense and complex operating systems.

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Operating System presentation on priority Scheduling, Queue Scheduling and multi level feedback scheduling with examples.

Scheduling is a method used to allocate computing resources like processor time, bandwidth, and memory to processes, threads, and applications. It aims to balance system load, ensure equal distribution of resources, and prioritize processes according to set rules. There are different types of scheduling including long-term, medium-term, and short-term scheduling. Scheduling algorithms decide which process from the ready queue is allocated the CPU based on whether the policy is preemptive or non-preemptive. Common algorithms include first-come first-served, shortest job first, priority scheduling, and round-robin scheduling.

CPU SCHEDULING

The document discusses various CPU scheduling algorithms used in operating systems. It describes the main objective of CPU scheduling as maximizing CPU utilization by allowing multiple processes to share the CPU. It then explains different scheduling criteria like throughput, turnaround time, waiting time and response time. Finally, it summarizes common scheduling algorithms like first come first served, shortest job first, priority scheduling and round robin scheduling.

CPU Scheduling is a function on which our operating system word This presentation contain all of the types of scheduling

The document discusses processes and process scheduling in operating systems. It defines a process as a program in execution that contains a program counter, stack, and data section. Processes can be in various states like new, ready, running, waiting, and terminated. A process control block contains information about each process like its state, program counter, memory allocation, and more. Scheduling aims to optimize CPU utilization, throughput, turnaround time, waiting time, and response time using algorithms like first come first serve, shortest job first, priority, and round robin scheduling.