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Multi-core Computing CPU Scheduling: Scheduling Algorithms and Criteria, Slides of Computer Science

An in-depth exploration of cpu scheduling in multi-core computing, covering objectives, scheduling, scheduling criteria, and algorithms such as first come first serve (fcfs), shortest job first (sjf), and preemptive sjf. It also discusses priority scheduling and its combination with sjf.

Typology: Slides

2012/2013

Uploaded on 03/28/2013

ekanath
ekanath 🇮🇳

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file:///D|/...ary,%20Dr.%20Sanjeev%20K%20Aggrwal%20&%20Dr.%20Rajat%20Moona/Multi-core_Architecture/lecture%2037/37_1.htm[6/14/2012 12:13:53 PM]
Module 19: Multi-core computing Operating Systems
Lecture 37: Multi-core computing CPU Scheduling
The Lecture Contains:
Contents
Scheduling
CPU Scheduling
When to Have CPU Scheduling
Scheduling Criteria
Scheduling Algorithms
Example (Contd.)
SJF
Example of “Guessing”
Preemptive SJF
Example (SRTF)
Adding Priority (Priority Scheduling)
Priority Scheduling + SJF
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Module 19: Multi-core computing Operating Systems

Lecture 37: Multi-core computing CPU Scheduling

The Lecture Contains:

Contents

Scheduling

CPU Scheduling

When to Have CPU Scheduling

Scheduling Criteria

Scheduling Algorithms

Example (Contd.)

SJF

Example of “Guessing”

Preemptive SJF

Example (SRTF)

Adding Priority (Priority Scheduling)

Priority Scheduling + SJF

Module 19: Multi-core computing Operating Systems

Lecture 37: Multi-core computing CPU Scheduling

Multi-core computing

Operating Systems

Contents

Scheduling Traditional Real time Multi-processor Synchronization and synchronization objects Inter-process communication Security

Multi-core computing

CPU Scheduling

Scheduling

To hide the effects of I/O Bursts and achieve higher CPU utilization To give a fair chance to all processes Short term scheduling CPU scheduling Long term scheduling Process admission policies Medium term scheduling Swap management

Module 19: Multi-core computing Operating Systems

Lecture 37: Multi-core computing CPU Scheduling

Scheduling Criteria

CPU Utilization (System centric) Keep CPU as much busy as possible Throughput (System centric) Number of processes completed/time Turnaround time (Process centric) Real time taken to complete a process Waiting time (Process centric) How much time a process is in ready queue Response time (Process centric) Factor for an interactive process Deadline (Real time behavior) Time guarantee to schedule a task.

Scheduling Algorithms

First Come First Serve (FCFS) Simplest implementation No preemption Shortest Job First (SJF) Optimal scheduling algorithm Minimum Average Waiting Time Difficulty: To know the time that it will take Batch systems: A good choice.

Module 19: Multi-core computing Operating Systems

Lecture 37: Multi-core computing CPU Scheduling

Example

Process Arrival Time CPU Burst Wait Time Turnaround P1 0 6 0 6 P2 4 20 2 22 P3 5 1 21 22

Example (Contd.)

Process Arrival Time CPU Burst Wait Time Turnaround P1 0 6 0 6 P2 4 20 3 23 P3 5 1 1 2

Module 19: Multi-core computing Operating Systems

Lecture 37: Multi-core computing CPU Scheduling

Preemptive SJF

When a new task arrives, the SJF is evaluated again and rescheduling can take place. aka Shortest-remaining-time-first (SRTF) scheduling

Example (SRTF)

Adding Priority (Priority Scheduling)

Simplest form is to add priority to a process. Select the highest priority job first Apply SJF/SRTF/FIFO/… scheduling only within a group of processes with the same priority

Priority scheduling + SJF