OS5 CPU Scheduling Algorithms (3) CPU Scheduling Algorithms (3) Shortest Remaining Time First(SRTF) Scheduleing Algorithm Preemptive version of SJF. Response time = start process time(?) - arrival time In any non-preemptive scheduleing algorithm, Response time = Waiting time but this not be true for preemptive scheduling algorithms First Come First Served(FCFS) Scheduling Algorithm - The process which has the least arrival time .. 2021. 12. 5. CPU Scheduling Algorithms (2) CPU Scheduling Algorithms preemptive scheduling algorithms non-preemptive scheduling algorithms CPU scheduling algorithms are applied only to processes which are in the ready state. Processes which are in I/O state will be blocked and so those processes will not be considered by schedulling algorithms while scheduling Shortest Job First Scheduling Algorithms process Id Arrival time burst time 1 .. 2021. 11. 28. CPU Scheduling Algorithms (1) CPU Scheduling Algorithms (1) 1) Long Term Scheduler RAM -> CPU 2) Short Term Scheduler Disk -> RAM 3) Medium Term Scheduler if RAM is FULL: decide what process changed(swaped?) RAM -> Disk context switch various times related to a process 1) arrival time RAM -> CPU arrival time 2) burst time (also called execution time) 3) completion time 4) turn-around time arrival time to completion time => (.. 2021. 11. 28. Operating System Concepts Operating System Concepts 1. Program vs Process, States of a process 실행중인 프로그램을 프로세스라고 한다. A program in execution is called as process Program vs Process 프로그램을 설치하면 Disk에 Compile이 된 상태로 저장된다. 그리고 이 프로그램을 실행하면 RAM에 프로그램을 복사한다. 이 과정을 자세히 보면 다음과 같다. 1. Disk에 인스턴스를 생성한다. (이것을 Process라고 한다.) 2. 생성한 인스턴스를 RAM으로 옮긴다. States of a process New State Disk에 인스턴스가 생성된 상태 Ready State 인스턴스가 RAM으로 이동되어 CPU가 처리할.. 2021. 11. 25. Introduction to Operating Systems Introduction to Operating Systems 1. Introduction to Operating Systems 컴퓨터는 문제를 풀기위한 하드웨어와 소프트웨어, 데이터로 구성된 시스템 combination of hardware, software and data which are used to solve problem of human beings 하드웨어 구성요소 CPU(Central Processing Unit) 컴퓨터에서 연산을 처리하는 유닛. Memory RAM 접근속도가 빠르지만 휘발성이다.(컴퓨터 종료시 사라짐) DISK 영구적으로 저장이 가능하지만 접근속도가 느리다. CACHE CPU 내부에 있는 저장공간 REGISTER 2. How hardware devices work toge.. 2021. 11. 25. 이전 1 다음