by Paul Lindberg

Introduction
You have existing code and you want to thread it so it runs best on a multicore system. What do you need to know to get started?

This article will show how you can start threading your code with OpenMP, help you decide where to thread, and show you how to measure the resulting code. I’ll also show some comparisons against typical Win32 threading.

An ever-increasing number of multicore processors are shipping today. As a result, developers need to add threads to their code to take advantage of multiple cores when they’re available, and split performance-sensitive code across those cores. However, your code must also scale well; the same code needs to run well on single-core machines, dual-core machines, quad-core machines and beyond. This paper looks at some common threading techniques using the OpenMP threading library, and measures their performance. This will give you some performance baselines to use, and help you understand how you can thread and measure your code.