Soft Real-Time Systems

by Buttazzo, Giorgio C.; Lipari, Giuseppe; Abeni, Luca; Caccamo, Marco

• ISBN13: 9780387237015
• ISBN10: 0387237011
• Format: Hardcover
• Copyright: 2005-05-31
• Publisher: Springer-Verlag New York Inc

Summary

Hard real-time systems are very predictable, but not sufficiently flexible to adapt to dynamic situations. They are built under pessimistic assumptions to cope with worst-case scenarios, so they often waste resources. Soft real-time systems are built to reduce resource consumption, tolerate overloads and adapt to system changes. They are also more suited to novel applications of real-time technology, such as multimedia systems, monitoring apparatuses, telecommunication networks, mobile robotics, virtual reality, and interactive computer games. This unique monograph provides concrete methods for building flexible, predictable soft real-time systems, in order to optimize resources and reduce costs. It is an invaluable reference for developers, as well as researchers and students in Computer Science.

Table of Contents

Preface	vii
Introduction	1	(22)
Basic terminology	1	(6)
From hard to soft real-time systems	7	(5)
Providing support for soft real-time systems	12	(11)
Overload Management	23	(36)
Introduction	23	(3)
Load definitions	26	(1)
Admission control methods	27	(12)
Performance degradation methods	39	(1)
Service adaptation	39	(3)
Job skipping	42	(5)
Period adaptation	47	(12)
Temporal Protection	59	(36)
Problems without temporal protection	59	(3)
Providing temporal protection	62	(5)
The GPS model	67	(2)
Proportional share scheduling	69	(5)
Resource reservation techniques	74	(4)
Resource reservations in dynamic priority systems	78	(10)
Temporal guarantees	88	(1)
Resource reservations in operating system kernels	89	(6)
Multi-Thread Applications	95	(38)
The thread model	95	(8)
Global approaches	103	(13)
Partition-based approaches	116	(14)
Concluding remarks and open problems	130	(3)
Synchronization Protocols	133	(42)
Terminology and notation	134	(1)
Shared resource in real-time systems	134	(1)
Synchronization protocols for hard real-time systems	135	(6)
Shared resources in soft real-time systems	141	(1)
Extending resource reservation with the SRP	142	(13)
Resource constraints in dynamic systems	155	(19)
Concluding remarks	174	(1)
Resource Reclaiming	175	(20)
Problems with reservations	175	(2)
The CASH algorithm	177	(5)
The Grub algorithm	182	(8)
Other forms of reclaiming	190	(5)
QoS Management	195	(24)
The QoS-based resource allocation model	195	(5)
Static vs. dynamic resource management	200	(2)
Integrating design & scheduling issues	202	(4)
Smooth rate adaptation	206	(13)
Feedback Scheduling	219	(16)
Controlling the number of missed deadlines	220	(2)
Adaptive reservations	222	(5)
Application level adaptation	227	(3)
Workload estimators	230	(5)
Stochastic Scheduling	235	(24)
Background and definitions	236	(2)
Statistical analysis of classical algorithms	238	(5)
Real-time queueing theory	243	(3)
Novel algorithms for stochastic scheduling	246	(7)
Reservations and stochastic guarantee	253	(6)
References	259	(12)
Index	271