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

Coarse-grained synchronization


There are two APIs which enable coarse-grained synchronization, they are clFlush and clFinish. The reason why we call coarse grained is that both lack control over the individual tasks queued on the command queue. These two functions have control only at the queue level.

cl_int clFlush (cl_command_queue command_queue);

This function ensures that all the commands, which are queued on the command_queue object will be submitted to the corresponding device. This does not guarantee that all the commands in the command_queue will be completed after clFlush returns.

First question which would arise is that what would happen if there is any blocking command queued to the device. Blocking commands do an implicit flush of the command_queue and on return from the blocking commands it will result in an implicit finish for the command_queue. This means that these functions will not return until this command gets completed. All the clEnqueueRead* and clEnqueueWrite* commands...