Book Image

The Art of Writing Efficient Programs

By : Fedor G. Pikus
3 (2)
Book Image

The Art of Writing Efficient Programs

3 (2)
By: Fedor G. Pikus

Overview of this book

The great free lunch of "performance taking care of itself" is over. Until recently, programs got faster by themselves as CPUs were upgraded, but that doesn't happen anymore. The clock frequency of new processors has almost peaked, and while new architectures provide small improvements to existing programs, this only helps slightly. To write efficient software, you now have to know how to program by making good use of the available computing resources, and this book will teach you how to do that. The Art of Efficient Programming covers all the major aspects of writing efficient programs, such as using CPU resources and memory efficiently, avoiding unnecessary computations, measuring performance, and how to put concurrency and multithreading to good use. You'll also learn about compiler optimizations and how to use the programming language (C++) more efficiently. Finally, you'll understand how design decisions impact performance. By the end of this book, you'll not only have enough knowledge of processors and compilers to write efficient programs, but you'll also be able to understand which techniques to use and what to measure while improving performance. At its core, this book is about learning how to learn.
Table of Contents (18 chapters)
1
Section 1 – Performance Fundamentals
7
Section 2 – Advanced Concurrency
11
Section 3 – Designing and Coding High-Performance Programs

Compilers optimizing code

The optimizing compiler is critically important for achieving high performance. Just try running a program compiled with no optimization at all to appreciate the role of the compiler: it is not uncommon for an unoptimized program (optimization level zero) to run an order of magnitude slower than the program compiled with all optimizations enabled.

Very often, however, it is the case that the optimizer can use some help from the programmer. This help can take the form of very subtle and often counter-intuitive changes. Before we look at some specific techniques to improve the optimization of your code, it helps to understand how the compiler sees your program.

Basics of compiler optimizations

The most important thing you must understand about optimization is that any code that is correct must remain correct. Correct here has nothing to do with your view of what is correct: the program may have bugs and give an answer you consider wrong, but the compiler...