This book is concerned with the design of operating systems, which is to say it enumerates the problems that pop up in the creation of efficient systems and explores alternative ways of dealing with them, detailing the advantages and shortcomings of each. For example, in their chapter on scheduling CPU activity, the authors explain several algorithms (first-come, first-served, and round-robin scheduling, among others) for allocating the capacity of single and multiple processors among jobs. They highlight the relative advantages of each, and explain how several real-life operating systems solve the problem. They then present the reader with exercises (this book is essentially a university textbook) that inspire thought and discussion. --David Wall