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

The thread-safe stack

One of the simplest data structures from the point of view of concurrency is the stack. All operations on the stack deal with the top element, so there is (conceptually, at least) a single location that needs to be guarded against races.

The C++ standard library offers us the std::stack container, so it makes a good starting point. All C++ containers, including the stack, offer the weak thread-safety guarantee: a read-only container can be safely accessed by many threads. In other words, any number of threads can call any const methods at the same time as long as no thread calls any non-const methods. While this sounds easy, almost simplistic, there is a subtle point here: there must be some kind of synchronization event accompanied by a memory barrier between the last modification of the object and the portion of the program where it is considered read-only. In other words, write access is not really done until all threads execute a memory barrier: the writer...