Use Lower Math Precision

OpenCL™ offers two basic ways to trade precision for speed:

In general, while the -cl-fast-relaxed-math flag is a quick way to get performance gains for kernels with many math operations, it does not permit fine numeric accuracy control. Consider experimenting with the native_* equivalents separately for each specific case, keeping track of the resulting accuracy.

Native_ versions of math built-ins are supported in hardware and run substantially faster, while offering lower accuracy. Use native trigonometry and transcendental functions, such as sin, cos, exp, and log, when performance is more important than precision.

For a full list of OpenCL build options and option descriptions, refer to the the OpenCL specification. For the instructions on how to use these options with the Intel® SDK for OpenCL™ Applications, refer to the following pages in the Developer Guide for Intel® SDK for OpenCL™ Applications: Build with OpenCL Offline Compiler Command Line Interface (for Intel® SDK for OpenCL™ Applications standalone version), Configuring OpenCL™ Build Options (for Intel® Code Builder for OpenCL™ API plugin for Microsoft Visual Studio*), Configuring Build Options (for Intel® Code Builder for OpenCL™ API plugin for Eclipse*).

See Also

Use Restrict Qualifier for Kernel Arguments
Developer Guide for Intel® SDK for OpenCL™ Applications
OpenCL™ 1.2 Specification at https://www.khronos.org/registry/OpenCL/specs/opencl-1.2.pdf