Book Image

OpenCL Programming by Example

Book Image

OpenCL Programming by Example

Overview of this book

Research in parallel programming has been a mainstream topic for a decade, and will continue to be so for many decades to come. Many parallel programming standards and frameworks exist, but only take into account one type of hardware architecture. Today computing platforms come with many heterogeneous devices. OpenCL provides royalty free standard to program heterogeneous hardware. This guide offers you a compact coverage of all the major topics of OpenCL programming. It explains optimization techniques and strategies in-depth, using illustrative examples and also provides case studies from diverse fields. Beginners and advanced application developers will find this book very useful. Beginning with the discussion of the OpenCL models, this book explores their architectural view, programming interfaces and primitives. It slowly demystifies the process of identifying the data and task parallelism in diverse algorithms. It presents examples from different domains to show how the problems within different domains can be solved more efficiently using OpenCL. You will learn about parallel sorting, histogram generation, JPEG compression, linear and parabolic regression and k-nearest neighborhood, a clustering algorithm in pattern recognition. Following on from this, optimization strategies are explained with matrix multiplication examples. You will also learn how to do an interoperation of OpenGL and OpenCL. "OpenCL Programming by Example" explains OpenCL in the simplest possible language, which beginners will find it easy to understand. Developers and programmers from different domains who want to achieve acceleration for their applications will find this book very useful.
Table of Contents (18 chapters)
OpenCL Programming by Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Finding the performance of your program?


In the ongoing process of optimization of an OpenCL program we need to find performance bottlenecks at each step so that we can improve on them. Here are some techniques for this investigation. In a Unix based system the time command provides user time, system time, and CPU time of a program-execution in detail. In Windows PowerShell, we use a built-in command called Measure-Command that gives total running time of a program. This is also similar to the linux time command. To get the execution time of a function or any part of code in C we can use either the clock_t clock (void); function or the time_t time (time_t* timer); and double difftime (time_t end, time_t beginning); functions from the standard header <time.h> or <ctime>. Those including several other techniques are good enough for measuring time of a CPU based program.

In OpenCL optimization, our area of interest is a bit different. As a part of optimization of the entire program...