Page 35 - DCAP608_REAL TIME SYSTEMS

Real Time Systems Gurwinder Kaur, Lovely Professional University

Notes Unit 3: Hard Versus Soft Real-time System

CONTENTS
Objectives
Introduction

3.1 Jobs and Processors
3.2 Release Time
3.3 Deadline and Timing Constraint

3.3.1 Deadline
3.3.2 Time Constraints
3.4 Hard and Soft Timing Constraint
3.4.1 Hard vs. Soft Deadlines
3.5 Hard Real-time Systems and Soft Real-time Systems

3.6 Summary
3.7 Keywords
3.8 Review Questions

3.9 Further Readings
Objectives

After studying this unit, you will be able to:
 Explain Jobs and Processors
 Define Release Time

 Enumerate Deadline and Timing Constraint
 Explain Hard and Soft Timing Constraint

Introduction

In this unit, we will study Jobs and Processors. We will also define release time. Further, we will
enumerate deadline and timing constraint. In the end, we will focus on hard and soft timing
constraint.

3.1 Jobs and Processors

A job is a unit of work that is scheduled by the system.

Example: Computation of a control law (digital controller), FFT computation on sample
data, transmission of a packet.
A job executes on a processor and may depend on some resources. A processor P is an active
object, for example, CPU, Transmission Link, Server.

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