What this book covers
Chapter 1, Introduction to Performance and Concurrency, talks about the reasons we care about the performance of programs, specifically about the reasons why good performance doesn't just happen. We learn why, in order to achieve the best performance, or, sometimes, even adequate performance, it is important to understand the different factors affecting performance and the reasons for a particular behavior of the program, be it fast or slow execution.
Chapter 2, Performance Measurements, is all about measurements. Performance is often non-intuitive, and all decisions involving efficiency, from design choices to optimizations, should be guided by reliable data. The chapter describes different types of performance measurements, explains how they differ and when they should be used, and teaches how to properly measure performance in different situations.
Chapter 3, CPU Architecture, Resources, and Performance Implications, helps us begin the study of the hardware and how to use it efficiently in order to achieve optimum performance. This chapter is dedicated to learning about CPU resources and capabilities, the optimal ways to use them, the more common reasons for not making the best use of CPU resources, and how to resolve them.
Chapter 4, Memory Architecture and Performance, helps us learn about modern memory architectures, their inherent weaknesses, and the ways to counter or at least hide these weaknesses. For many programs, the performance is entirely dependent on whether the programmer takes advantage of the hardware features designed to improve memory performance, and this chapter teaches the necessary skills to do so.
Chapter 5, Threads, Memory, and Concurrency, helps us continue our study of the memory system and its effects on performance, but now we extend our study to the domain of multi-core systems and multithreaded programs. It turns out that the memory, which was already the "long pole" of performance, is even more of a problem when we add concurrency. While the fundamental limits imposed by the hardware cannot be overcome, most programs aren't performing even close to these limits, and there is a lot of room for a skillful programmer to improve the efficiency of their code; this chapter gives the reader the necessary knowledge and tools to do so.
Chapter 6, Concurrency and Performance, helps you learn about developing high-performance concurrent algorithms and data structures for thread-safe programs. On the one hand, to take full advantage of concurrency, we must take a high-level view of the problem and the solution strategy: data organization, work partitioning, and sometimes even the definition of what constitutes a solution are the choices that critically affect the performance of the program. On the other hand, as we have seen in the last chapter, performance is greatly impacted by low-level factors such as the arrangement of the data in the cache, and even the best design can be ruined by poor implementation.
Chapter 7, Data Structures for Concurrency, explains the nature of data structures in concurrent programs and how the familiar definitions of data structures such as "stack" and "queue" mean something else when the data structure is used in a multithreaded context.
Chapter 8, Concurrency in C++, describes the features for concurrent programming that were added to the language recently in the C++17 and C++20 standards. While it is too early to talk about the best practices when using these features for optimum performance, we can describe what they do, as well as the current state of compiler support.
Chapter 9, High-Performance C++, switches our focus from the optimal use of the hardware resources to the optimal application of a particular programming language. While everything we have learned so far can be applied, usually quite straightforwardly, to any program in any language, this chapter deals with C++ features and idiosyncrasies. The reader will learn which features of the C++ language are likely to cause performance problems and how to avoid them. The chapter will also cover the very important matter of compiler optimizations and how the programmer can help the compiler to generate more efficient code.
Chapter 10, Compiler Optimizations in C++, covers compiler optimizations and how the programmer can help the compiler to generate more efficient code.
Chapter 11, Undefined Behavior and Performance, has a dual focus. On the one hand, it explains the dangers of the kinds of undefined behavior that programmers often ignore when attempting to squeeze the most performance from their code. On the other hand, it explains how we can take advantage of undefined behavior to improve performance and how to properly specify and document such situations. Overall, the chapter offers a somewhat usual but more relevant way to understand the issue of undefined behavior compared to the usual "anything can happen."
Chapter 12, Design for Performance, reviews all the performance-related factors and features we have learned in this book and explores the subject of how the knowledge and understanding we have gained should influence the design decisions we make when developing a new software system or rearchitecting an existing one.
