SCHEDULING ALGORITHMS

It consists of CPU scheduling algorithms, examples, scheduling problems, realtime scheduling algorithms and issues. Multiprocessing and multicore scheduling.

The document discusses several key process scheduling policies and algorithms: 1. Maximum throughput, minimize response time, and other policies aim to optimize different performance metrics like job completion time. 2. Common scheduling algorithms include first come first served (FCFS), shortest job next (SJN), priority scheduling, round robin, and multilevel queues. Each has advantages for different workload types. 3. The document also covers process synchronization challenges like deadlock and livelock that can occur when processes contend for shared resources in certain ordering. Methods to avoid or recover from such issues are important for system design.

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.

Deadlocks-An Unconditional Waiting Situation in Operating System. We must make sure of This concept well before understanding deep in to Operating System. This PPT will understands you to get how the deadlocks Occur and how can we Detect, avoid and Prevent the deadlocks in Operating Systems.

1) A semaphore consists of a counter, a waiting list, and wait() and signal() methods. Wait() decrements the counter and blocks if it becomes negative, while signal() increments the counter and resumes a blocked process if the counter becomes positive. 2) The dining philosophers problem is solved using semaphores to lock access to shared chopsticks, with one philosopher designated as a "weirdo" to avoid deadlock by acquiring locks in a different order. 3) The producer-consumer problem uses three semaphores - one to limit buffer size, one for empty slots, and one for locks - to coordinate producers adding to a bounded buffer

This document discusses several techniques for clock synchronization in distributed systems: 1. Time stamping events and messages with logical clocks to determine partial ordering without a global clock. Logical clocks assign monotonically increasing sequence numbers. 2. Clock synchronization algorithms like NTP that regularly adjust system clocks across the network to synchronize with a time server. NTP uses averaging to account for network delays. 3. Lamport's logical clocks algorithm that defines "happened before" relations and increments clocks between events to synchronize logical clocks across processes.

The document discusses deadlocks in computer systems. It defines deadlock, presents examples, and describes four conditions required for deadlock to occur. Several methods for handling deadlocks are discussed, including prevention, avoidance, detection, and recovery. Prevention methods aim to ensure deadlocks never occur, while avoidance allows the system to dynamically prevent unsafe states. Detection identifies when the system is in a deadlocked state.

This document discusses various techniques for process synchronization. It begins by defining process synchronization as coordinating access to shared resources between processes to maintain data consistency. It then discusses critical sections, where shared data is accessed, and solutions like Peterson's algorithm and semaphores to ensure only one process accesses the critical section at a time. Semaphores use wait and signal operations on a shared integer variable to synchronize processes. The document covers binary and counting semaphores and provides an example of their use.

This document discusses various disk scheduling algorithms: - FCFS handles requests sequentially but suffers from the global zigzag effect. - SSTF selects the request with the minimum seek time, reducing total head movement but risking starvation. - SCAN and C-SCAN move the disk arm back and forth, providing more uniform wait times. - LOOK and C-LOOK only move as far as the last request in each direction before reversing. Circular versions like C-SCAN are more fair but have larger total seek times. The optimal algorithm depends on disk load and request patterns.

Operating System Topic Memory Management for Btech/Bsc (C.S)/BCA... Memory management is the functionality of an operating system which handles or manages primary memory. Memory management keeps track of each and every memory location either it is allocated to some process or it is free. It checks how much memory is to be allocated to processes. It decides which process will get memory at what time. It tracks whenever some memory gets freed or unallocated and correspondingly it updates the status.

This document describes the Shortest Job First (SJF) CPU scheduling algorithm. SJF prioritizes processes in the ready queue based on the shortest estimated CPU burst time so that the process with the shortest burst time is selected first. SJF aims to minimize average waiting times and turnaround times. However, it requires accurate predictions of burst times and cannot always be implemented in practice due to lack of future knowledge.

This Presentation is for Memory Management in Operating System (OS). This Presentation describes the basic need for the Memory Management in our OS and its various Techniques like Swapping, Fragmentation, Paging and Segmentation.