Operating SystemsThree Easy Pieces（带详细整理书签）.pdf

Preface

To Everyone

Welcome to this book! We hope you’ll enjoy reading it as much as we enjoyed

writing it. The book is called Operating Systems: Three Easy Pieces (available

at http://www.ostep.org), and the title is obviously an homage to one of the

greatest sets of lecture notes ever created, by one Richard Feynman on the topic of

Physics [F96]. While this book will undoubtedly fall short of the high standard set

by that famous physicist, perhaps it will be good enough for you in your quest to

understand what operating systems (and more generally, systems) are all about.

particular problem and then show how to solve it. The chapters are short, and try

(as best as possible) to reference the source material where the ideas really came

from. One of our goals in writing this book is to make the paths of history as clear

as possible, as we think that helps a student understand what is,whatwas,and

what will be more clearly. In this case, seeing how the sausage was made is nearly

as important as understanding what the sausage is good for

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.

There are a couple devices we use throughout the book which are probably

worth introducing here. The first is t he crux of the problem. Anytime we are

trying to solve a problem, we first try to state what the most important issue is;

when a journaling file system writes a block to disk, you have taken the first steps

towards mastery of storage systems.

There are also numerous asides and tips throughout the text, adding a little

color to the mainline presentation. Asides tend to discuss something relevant (but

perhaps not essential) to the main text; tips tend to be general lessons that can be

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Hint: eating! Or if you’re a vegetarian, running away from.

applied to systems you build. An index at the end of the book lists all of these tips

matter entirely.

At the beginning of each major section, we’ll first present an abstraction that an

operating system provides, and then work in subsequent chapters on the mecha-

nisms, policies, and other support needed to provide the abstraction. Abstractions

are fundamental to all aspects of Computer Science, so it is perhaps no surprise

that they are also essential in operating systems.

Throughout the chapters, we try to use real code (not pseudocode)wherepos-

sible, so for virtually all examples, you should be able to type them up yourself and

run them. Running real code on real systems is the best way to learn about operat-

ing systems, so we encourage you to do so when you can. We are also making code

ing feature: by giving them a different ra ndom seed, you can generate a virtually

infinite set of problems; the simulators can also be told to solve the problems for

you. Thus, you can test and re-test yourself until you have achieved a good level

of understanding.

The most important addendum to this book is a set of projects in which you

learn about how real systems work by designing, implementing, and testing your

own code. All projects (as well as the code examples, mentioned above) are in

the Cprogramminglanguage[KR88]; C is a simple and po werful language that

underlies most operating systems, and thus worth adding to your tool-chest of

languages. Two types of projects are available (see the onlineappendixforideas).

a mix of both.

We are slowly making project descriptions, and a t esting framework, avail-

able. See https://github.com/remzi-arpacidusseau/ostep-projects

for more information. If not part of a class, this will give you a chance to do these

projects on your own, to better learn the material. Unfortunately, yo u d on’t ha ve

a TA to bug when you get stuck, but not everything in life can be free (but books

can be!).

To Educators

The (current) proper citation for the book is as follows:

The course divides fairly well across a 15-week semester, in which you can

cover most of the topics within at a reasonable level of depth. Cramming the

course into a 10-week quarter probably requires dropping some detail from each

of the pieces. There are also a few chapters on virtual machine monitors, which w e

concurrency problem arises, or why they are trying to solve it, if they don’t yet un-

occur at arbitrary points in time. Once they do understand these concepts, how-

ever, introducing the notion of threads and the problems that arise due to them

becomes rather easy, or at least, easier.

As much as is possible, we use a chalkboard (or whiteboard) to deliver a lec-

ture. On these mo re conceptual days, we come to class with a few majorideas

and examples in mind and use the board to present them. Handouts are useful

to give the students concrete problems to solve based on the material. On more

practical days, we simply plug a laptop into the projector and show real code; this

contributed their materials as well.

One last request: if you use the free online chapters, please just link to them,

instead of making a local copy. This helps us track usage (over 1 million chapters

downloaded in the past few years!) and also ensures students getthelatest(and

greatest?) version.

EASY

PIECES

To Students

regardless of which part of the world they come from or how much they are willing

to spend for a book. Failing that, it is one free book, which is better than none.

We also hope, where possible, to point you to the original sources of much

of the material in the book: the great papers and persons who have shaped the

field of operating systems over the years. Ideas are not pulled out of the air; they

come from smart and hard-working people (including numerous Turing-award

winners

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), and thus we should strive to celebrate those ideas and people where

possible. In doing so, we hopefully can better understand the revolutions that

have taken place, instead of writing texts as if those thoughts have alwa ys been

Acknowledgments

Colorado Springs), Ali Razeen (Duke), Alistair Martin, AmirBehzad Eslami, Anand Mundada,

Andrew Mahler, Andrew Valencik (Saint Mary’s), Angela Demke Brown (Toronto), Antonella

Bernobich (UoPeople)*, Arek Bulski, B. Brahmananda Reddy (Minnesota), Bala Subrahmanyam

Kambala, Bart Miller, Ben Kushigian (U. Mass), Benita Bose, Biswajit Mazumder (Clemson),

Bobby Jack, Bj

orn Lindberg, Brandon Harshe (U. Minn), Brennan Payne, Brian Gorman, Brian

Kroth, Caleb Sumner (Southern Adventist), Cara Lauritzen, Charlotte Kissinger, Cheng Su,

Chien-Chung Shen (Delaware)*, Christian Stober, Christoph Jaeger, C.J. Stanbridge (Memorial

U. of Newfoundland), Cody Hanson, Constantinos Georgiades, Dakota Crane (U. Washington-

Tacoma), Dan Soendergaard (U. Aarhus), Dan Tsafrir (Technion), Danilo Bruschi (Universita