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ADVANCED OPENCL TM AND 

OPENGL® DEBUGGING AND 

PROFILING 

Yaki Tebeka 

AMD 

Fellow, Developer Tools

OPENCL TM 

OpenCL 

– A framework for writing parallel computing applications that execute 

across heterogeneous platforms consisting of APUs, CPUs, GPUs 

and other processors 

– Enables both task-based and data-based parallelism 

– An open, royalty-free, cross-platform standard, managed by 

the Khronos Group 

– Implementations are available from: 

AMD, Intel, NVIDIA, Apple, IBM, ARM, … 

3 | Advanced OpenCL and OpenGL Debugging and Profiling | June 2011

OPENGL® 

OpenGL 

– A software interface for 2D and 3D graphics hardware 

– An open, royalty-free, cross-platform standard managed by the Khronos Group 

– Widely used on Windows, Linux, Mac, Solaris, … 

– OpenGL|ES is the de-facto standard for 3D graphics on embedded systems 


PARALLEL COMPUTING OVER APUS AND GPUS 

APUs and GPUs are massively multithreaded 

– Hundreds of cores 

– Thousands of concurrent threads 

Ideal for parallel computing tasks 

– A lot of horse power, optimized for parallel computing 

– Significantly faster than multi-core CPUs 

– Order of magnitude performance improvement 


DEBUGGING AND PROFILING MODEL 

Debugging and Profiling GPU based applications is hard 

On-time delivery of robust (bug-free) 3D graphics and 

parallel computing applications is challenging 

It is virtually impossible to optimize an application to 

fully utilize the available parallel computing system resources 


DEBUGGING AND PROFILING MODEL 

OpenCL is a “Black Box” 

The application enqueues OpenCL commands 

The OpenCL runtime executes the commands 

The developer cannot 

– Debug the OpenCL kernels 

– See the execution details 

– View runtime loads 

7 | Advanced OpenCL and OpenGL Debugging and Profiling | June 2011 

Application

gDEBUGGER TM 

gDEBugger for 

Microsoft Visual Studio® 

An OpenCL and OpenGL 

Debugger 

– API Level 

– OpenCL Kernel 

Source Code 

Integrated into Microsoft 

Visual Studio 

Provides the information a 

developer needs to find bugs 

and optimize an applications 

memory consumption 


DEMO 

Smoke Simulation Sample 

A sample application provided with gDEBugger 

Simulates smoke on 3D grids (density, velocity, temperature) 

OpenCL kernels solve Navier-Stokes equations 

A 3D texture is shared between OpenCL and OpenGL 

A density field grid is copied into 3D texture 

OpenGL renders the 3D density texture 


GDEBUGGER 

API Calls History View 

Displays a log of OpenCL and OpenGL API calls 

Call details are displayed in the Properties view 


gDEBUGGER 

gDEBugger Explorer 

Displays OpenCL and OpenGL allocated objects 

Marks OpenGL-OpenCL shared contexts 

Focuses the GUI views on objects 

Double-click displays each object in the 

appropriate view 


gDEBUGGER 

Source Code and Call Stack 

Displays C, C++ and 

OpenCL C source code 

Enables setting source 

code breakpoints 

Displays a combined C, C++ 

and OpenCL C call stack 


gDEBUGGER 

Watch Views 

Displays OpenCL kernel’s variable values and types 


gDEBUGGER 

Multi Watch View 

Displays the values of an 

OpenCL kernel variable across 

all work items and work groups 

The image view provides a 

graphics representation of the 

data (each pixel represents a 

single work item) 


gDEBUGGER 

Current Work Item Toolbar 

Enables the selection of the focused work item 

The watch views will display the focused work item’s variables values 

When stepping through code, code locations where the focused work item is not valid will be skipped 


gDEBUGGER 

Memory View 

Displays information about the application’s compute and graphic memory consumption 

Displays the call stack that existed at object creation 

Detects memory leaks 


gDEBUGGER 

Statistics View 

Displays statistical information about the application’s 

OpenCL and OpenGL APIs usage 

– A breakdown of the types of API functions used 

– Warnings about unrecommended and deprecated API usage 

– OpenGL vertex batches information 


PROFILING WITH AMD APP PROFILER 

AMD APP Profiler 

A performance analysis tool that gathers data from the OpenCL run-time and 

AMD Radeon TM GPUs during the execution of an OpenCL application 

Integrated into Microsoft Visual Studio® 2008 and 2010 

Command line utility program for Windows and Linux® platforms 

Support OpenCL and DirectCompute 

No custom driver requirements 

No code or project modifications to target application necessary 

http://developer.amd.com/gpu/AMDAPPProfiler 


AMD APP PROFILER 


PROFILING USING AMD APP KERNELANALYZER AND GPU SHADERANALYZER 

AMD APP KernelAnalyzer and GPU Shader Analyzer 

Static analysis tools to compile, analyze and disassemble OpenCL C kernels, HLSL and GLSL shaders 

Compile and analyze for multiple Catalyst drivers and GPU device targets 

View compilation warning and error messages 

View AMD Intermediate Language (IL) and hardware disassembly (ISA) code 

View various statistics generated by analyzing the ISA code 

http://developer.amd.com/gpu/AMDAPPKernelAnalyzer 

http://developer.amd.com/gpu/shader 


AMD APP KERNELANALYZER AND GPU SHADERANALYZER 


PROFILING USING AMD CODE ANALYST 

AMD CODE ANALYST 

Performance analysis tool for AMD CPUs 

Find CPU performance hotspots and issues 

Drill down to functions, source code and individual instructions 

Tune both managed and native code (Java, OpenCL, C, C++, Fortran) 

Analyze programs on multi-core and NUMA platforms 

Available as a standalone product and as a Visual Studio extension 

http://developer.amd.com/cpu/CodeAnalyst 


AMD CODE ANALYST 


DEBUGGING AND PROFILING USING GPU PERF STUDIO 

GPU PerfStudio 

Performance analysis tool for AMD GPUs and APUs 

Integrates four tools aimed for graphics developers 

– Frame Debugger 

– Frame Profiler 

– Shader Debugger 

– API Trace 

http://developer.amd.com/gpu/PerfStudio 


GPU PERF STUDIO 


DEBUGGING AND PROFILING USING GDEBUGGER STANDALONE 

gDEBugger Stand-alone 

An OpenGL and OpenCL debugger, profiler and memory analyzer 

Provides the information a developer needs to find bugs and optimize application performance 

Available for Windows, Mac and Linux 

http://www.gremedy.com/products.php 


gDEBUGGER STANDALONE 


QUESTIONS

Disclaimer & Attribution 

The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and 

typographical errors. 

The information contained herein is subject to change and may be rendered inaccurate for many reasons, including but not limited to product 

and roadmap changes, component and motherboard version changes, new model and/or product releases, product differences between 

differing manufacturers, software changes, BIOS flashes, firmware upgrades, or the like. There is no obligation to update or otherwise correct or 

revise this information. However, we reserve the right to revise this information and to make changes from time to time to the content hereof 

without obligation to notify any person of such revisions or changes. 

NO REPRESENTATIONS OR WARRANTIES ARE MADE WITH RESPECT TO THE CONTENTS HEREOF AND NO RESPONSIBILITY IS 

ASSUMED FOR ANY INACCURACIES, ERRORS OR OMISSIONS THAT MAY APPEAR IN THIS INFORMATION. 

ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE ARE EXPRESSLY DISCLAIMED. 

IN NO EVENT WILL ANY LIABILITY TO ANY PERSON BE INCURRED FOR ANY DIRECT, INDIRECT, SPECIAL OR OTHER 

CONSEQUENTIAL DAMAGES ARISING FROM THE USE OF ANY INFORMATION CONTAINED HEREIN, EVEN IF EXPRESSLY ADVISED 

OF THE POSSIBILITY OF SUCH DAMAGES. 

AMD, AMD Radeon, gDEBugger, the AMD arrow logo, and combinations thereof are trademarks of Advanced Micro Devices, Inc. All other 

names used in this presentation are for informational purposes only and may be trademarks of their respective owners. 

OpenCL and OpenGL logo are trademarks of Apple Inc. used by permission by Khronos. 

Windows and Visual Studio are registered trademarks of Microsoft Corporation. 

Mac is a registered trademark of Apple Inc. 

Linux is a registered trademark of Linus Torvalds. 

© 2011 Advanced Micro Devices, Inc. All rights reserved.

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