Feedback control for computer systems / Philipp K. Janert.

Format:

Book

Author/Creator:

Janert, Philipp K.

Language:

English

Subjects (All):

Control theory--Computer programs.

Control theory.

Web site development.

Physical Description:

1 online resource (329 p.)

Edition:

1st edition

Place of Publication:

North Sebastopol, California : O'Reilly, 2013.

Language Note:

English

System Details:

text file

Summary:

How can you take advantage of feedback control for enterprise programming? With this book, author Philipp K. Janert demonstrates how the same principles that govern cruise control in your car also apply to data center management and other enterprise systems. Through case studies and hands-on simulations, you’ll learn methods to solve several control issues, including mechanisms to spin up more servers automatically when web traffic spikes.

Contents:

Machine generated contents note: pt. I Foundations

1.Why Feedback? An Invitation

A Hands-On Example

Hoping for the Best

Establishing Control

Adding It Up

Summary

Code to Play With

2.Feedback Systems

Systems and Signals

Tracking Error and Corrective Action

Stability, Performance, Accuracy

The Setpoint

Uncertainty and Change

Feedback and Feedforward

Feedback and Enterprise Systems

3.System Dynamics

Lags and Delays

Forced Response and Free Response

Transient Response and Steady-State Response

Dynamics in the Physical World and in the Virtual World

Dynamics and Memory

The Importance of Lags and Delays for Feedback Loops

Avoiding Delays

Theory and Practice

4.Controllers

Block Diagrams

On/Off Control

Proportional Control

Why Proportional Control Is Not Enough

Integral Control

Integral Control Changes the Dynamics

Integral Control Can Generate a Constant Offset

Derivative Control

Problems with Derivative Control

The Three-Term or PID Controller

5.Identifying Input and Output Signals

Control Input and Output

Directionality of the Input/Output Relation

Examples

Thermal Control 1 Heating

Item Cache

Server Scaling

Controlling Supply and Demand by Dynamic Pricing

Thermal Control 2 Cooling

Criteria for Selecting Control Signals

For Control Inputs

For Control Outputs

A Note on Multidimensional Systems

6.Review and Outlook

The Feedback Idea

Iteration

Process Knowledge

Avoiding Instability

pt. II Practice

7.Theory Preview

Frequency Representation

The Transfer Function

Block-Diagram Algebra

PID Controllers

Poles of the Transfer Function

Process Models

8.Measuring the Transfer Function

Static Input/Output Relation: The Process Characteristic

Practical Considerations

Dynamic Response to a Step Input: The Process Reaction Curve

Practical Aspects

Self-Regulating Process

Accumulating Process

Self-Regulating Process with Oscillation

Non-Minimum Phase System

Other Methods of System Identification

9.PID Tuning

Tuning Objectives

General Effect of Changes to Controller Parameters

Ziegler-Nichols Tuning

Semi-Analytical Tuning Methods

A Closer Look at Controller Tuning Formulas

10.Implementation Issues

Actuator Saturation and Integrator Windup

Preventing Integrator Windup

Setpoint Changes and Integrator Preloading

Smoothing the Derivative Term

Choosing a Sampling Interval

Variants of the PID Controller

Incremental Form

Error Feedback Versus Output Feedback

The General Linear Digital Controller

Nonlinear Controllers

Error-Square and Gap Controllers

Simulating Floating-Point Output

Categorical Output

11.Common Feedback Architectures

Changing Operating Conditions: Gain Scheduling

Gain Scheduling for Mildly Nonlinear Systems

Large Disturbances: Feedforward

Fast and Slow Dynamics: Nested or "Cascade" Control

Systems Involving Delays: The Smith Predictor

pt. III Case Studies

12.Exploring Control Systems Through Simulation

The Case Studies

Modeling Time

Control Time

Simulation Time

The Simulation Framework

Components

Plants and Systems

Controllers

Actuators and Filters

Convenience Functions for Standard Loops

Generating Graphical Output

13.Case Study: Cache Hit Rate

Defining Components

Cache Misses as Manufacturing Defects

Measuring System Characteristics

Controller Tuning

Simulation Code

14.Case Study: Ad Delivery

The Situation

Improving Performance

Variations

Cumulative Goal

Gain Scheduling

Integrator Preloading

Weekend Effects

15.Case Study: Scaling Server Instances

Measuring and Tuning

Reaching 100 Percent With a Nonstandard Controller

Dealing with Latency

16.Case Study: Waiting-Queue Control

On the Nature of Queues and Buffers

The Architecture

Setup and Tuning

Derivative Control to the Rescue

Controller Alternatives

17.Case Study: Cooling Fan Speed

The Model

Tuning and Commissioning

Closed-Loop Performance

18.Case Study: Controlling Memory Consumption in a Game Engine

Problem Analysis

Architecture Alternatives

A Nontraditional Loop Arrangement

A Traditional Loop with Logarithms

Results

19.Case Study Wrap-Up

Simple Controllers, Simple Loops

Staying in Control

Dealing with Noise

pt. IV Theory

20.The Transfer Function

Differential Equations

Laplace Transforms

Properties of the Laplace Transform

Using the Laplace Transform to Solve Differential Equations

A Worked Example

Worked Example: Step Response

Worked Example: Ramp Input

The Harmonic Oscillator

What If the Differential Equation Is Not Known?

21.Block-Diagram Algebra and the Feedback Equation

Composite Systems

The Feedback Equation

An Alternative Derivation of the Feedback Equation

Limitations and Importance of Transfer Function Methods

22.PID Controllers

The Transfer Function of the PID Controller

The Canonical Form of the PID Controller

The General Controller

Proportional Droop Revisited

23.Poles and Zeros

Structure of a Transfer Function

Effect of Poles and Zeros

Special Cases and Additional Details

Pole Positions and Response Patterns

Dominant Poles

Pole Placement

What to Do About Delays

24.Root Locus Techniques

Construction of Root Locus Diagrams

Root Locus or "Evans" Rules

Angle and Magnitude Criteria

Practical Issues

Simple Lag with a P Controller

Simple Lag with a PI Controller

25.Frequency Response and the Bode Plot

Frequency Response

Frequency Response in the Physical World

Frequency Response for Transfer Functions

The Bode Plot

A Criterion for Marginal Stability

Other Graphical Techniques

26.Topics Beyond This Book

Discrete-Time Modeling and the z-Transform

State-Space Methods

Robust Control

Optimal Control

Mathematical Control Theory

pt. V Appendices.

Notes:

Includes index.

Includes bibliographical references and index.

Description based on online resource; title from PDF title page (ebrary, viewed November 5, 2013).

ISBN:

9781449362669

1449362664

9781306810807

1306810809

9781449362645

1449362648

9781449362652

1449362656

OCLC:

868963558