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

Performance benchmarking

The easiest way to collect information about the performance of a program is to run it and measure how long it takes. Of course, we need more data than that to make any useful optimizations: it would be nice to know which parts of the program make it take that long, so we don't waste our own time optimizing the code that may be very inefficient but also takes very little time and thus does not contribute to the bottom line.

We already saw a simple example of that when we added a timer to our sample program: now we know how long the sort itself takes. That is, in a nutshell, the whole idea of benchmarking. The rest is elbow grease, instrumenting the code with timers, collecting the information, and reporting it in a useful format. Let us see what tools we have for that, starting with the timers provided by the language itself.

C++ chrono timers

C++ has some facilities that can be used to collect timing information in its chrono library. You can...