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

Event-based or fine-grained synchronization


OpenCL has an event-based synchronization mechanism. These event handles identify the unique commands in the queue and can be used for synchronizing algorithm execution. It can also be used for profiling the queued task. We will discuss more about profiling in a later section. OpenCL event is an object which holds the state of the task. An OpenCL event state is defined as one of the following stages based on the life time of the task:

  • CL_QUEUED: The command is enqueued into the command_queue queue, but it has not yet been submitted to the device. This state is the first state for all events except for the user events.

  • CL_SUBMITTED: This state means that the host has submitted this command to the host. All user events reach this state before running.

  • CL_RUNNING: When the command is dequeued on the device the event reaches the state of CL_RUNNING. The device has started to execute this command. If this event is waiting for other events to complete then...