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Diffstat (limited to 'doc/source/reference/simd')
| -rw-r--r-- | doc/source/reference/simd/how-it-works.rst | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/doc/source/reference/simd/how-it-works.rst b/doc/source/reference/simd/how-it-works.rst index 19b3dba45..8fe00af89 100644 --- a/doc/source/reference/simd/how-it-works.rst +++ b/doc/source/reference/simd/how-it-works.rst @@ -1,6 +1,6 @@ -********************************** -How does the CPU dispatcher work? -********************************** +********************************************** +How does the CPU dispatcher work (build time)? +********************************************** NumPy dispatcher is based on multi-source compiling, which means taking a certain source and compiling it multiple times with different compiler @@ -347,3 +347,21 @@ through ``--cpu-dispatch``, but it can also represent other options such as: // #include "hello2.dispatch.h" // DISPATCH_CALL_HIGH(another_function, ("the highest interest")) } + + +.. _runtime-simd-dispatch:: + +********************************************** +How does the CPU dispatcher work (run time)? +********************************************** + +Importing NumPy triggers a scan of the available CPU features from the set +of dispatchable features. This can be further restricted by setting the +environment variable ``NPY_DISABLE_CPU_FEATURES`` to a comma-, tab-, or +space-separated list of features to disable. This will raise an error if +parsing fails or if the feature was not enabled. For instance, on ``x86_64`` +this will disable ``AVX2`` and ``FMA3``:: + + NPY_DISABLE_CPU_FEATURES="AVX2,FMA3" + +If the feature is not available, a warning will be emitted. |