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

Concurrency support in C++20

C++20 added a few enhancements here and there to the existing concurrency support, but we are going to focus on the major new addition: coroutines. Coroutines, in general, are functions that can be interrupted and resumed. They are useful in several major applications: they can greatly simplify writing event-driven programs, they are almost unavoidable for work-stealing thread pools, and they make writing asynchronous I/O and other asynchronous code much easier.

The foundations of coroutines

There are two styles of coroutines: stackful and stackless. Stackful coroutines are also sometimes called fibers; they are similar to functions wherein their state is allocated on the stack. Stackless coroutines have no corresponding stack allocations, their state is stored on the heap. In general, stackful coroutines are more powerful and flexible, but stackless coroutines are significantly more efficient.

In this book, we will focus on stackless coroutines...