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Wrapping the Right Set of Operations ...................................................................... 45
Profiling Operations Using OpenCL™ Profiling Events .......................................................... 46
Comparing OpenCL™ Kernel Performance with Performance of Native Code .......................... 47
Getting Credible Performance Numbers ............................................................................. 47
Using Tools.................................................................................................................... 48
Using Multiple OpenCL™ Devices ........................................................................................ 50
Using Shared Context for Multiple OpenCL™ Devices .......................................................... 50
Sharing Resources Efficiently ........................................................................................... 50
Synchronization Caveats ................................................................................................. 51
Writing to a Shared Resource .......................................................................................... 52
Partitioning the Work ...................................................................................................... 53
Keeping Kernel Sources the Same .................................................................................... 54
Basic Frequency Considerations ....................................................................................... 54
Eliminating Device Starvation .......................................................................................... 55
Limitations of Shared Context with Respect to Extensions ................................................... 55
Coding for the Intel® CPU OpenCL™ Device ........................................................................ 56
Vectorization Basics for Intel® Architecture Processors ....................................................... 56
Benefitting From Implicit Vectorization .............................................................................. 57
Vectorizer Knobs ............................................................................................................ 57
Using Vector Data Types ................................................................................................. 58
Writing Kernels to Directly Target the Intel® Architecture Processors ................................... 59
Work-Group Size Considerations ...................................................................................... 61
Work-Group Level Parallelism .......................................................................................... 61
OpenCL™ Kernel Development for Intel® CPU OpenCL™ device .......................................... 62
Why Optimizing Kernel Code Is Important? ....................................................................... 62
Avoid Spurious Operations in Kernel Code ......................................................................... 62
Perform Initialization in a Separate Task ........................................................................... 63
Use Preprocessor for Constants ........................................................................................ 64
Use Signed Integer Data Types ........................................................................................ 65
Use Row-Wise Data Accesses ........................................................................................... 65
Tips for Auto-Vectorization .............................................................................................. 66
Local Memory Usage ....................................................................................................... 68
Avoid Extracting Vector Components ................................................................................ 68
Task-Parallel Programming Model Hints............................................................................. 69
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