Avoiding Nested Parallelization

Nested parallelization may occur if you use a threaded Intel IPP function in a multithreaded application. Nested parallelization may cause performance degradation because of thread oversubscription.

For applications that use OpenMP threading, nested threading is disabled by default, so this is not an issue.

However, if your application uses threading created by a tool other than OpenMP*, you must disable multi-threading in the threaded Intel IPP function to avoid this issue.

Disabling Multi-threading (Recommended)

The best option to disable multi-threading is to link your application with the Intel® IPP single-threaded (non-threaded) libraries included in the default package and discontinue use of the separately downloaded multi-threaded versions.

You may also call the ippSetNumThreads function with parameter 1, but this method may still incur some OpenMP* overhead.

Optimization Notice

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804

For more complete information about compiler optimizations, see our Optimization Notice.
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