Certain low-level code in Drake will scan for available CPU features at runtime and dispatch to CPU-optimized implementations.

This offers the best performance, but can lead to different results when running on different hardware. Users can set the environment variable DRAKE_DISABLE_CPU_FEATURES to a comma-separated list of CPU features to not use at runtime. This is the same idea as NumPy's runtime dispatch. Drake first checks if DRAKE_DISABLE_CPU_FEATURES is set and if not then falls back to check NPY_DISABLE_CPU_FEATURES instead, so that users only need to set one variable.

If both DRAKE_DISABLE_CPU_FEATURES and NPY_DISABLE_CPU_FEATURES are unset, then all runtime dispach features are enabled (maximum performance). If DRAKE_DISABLE_CPU_FEATURES is set to the empty string, then all runtime dispach features are enabled (maximum performance). This is true even when NPY_DISABLE_CPU_FEATURES is set. The Drake option always has precedence.

For the full list of feature strings which can be disabled, refer to the NumPy list of features.

For example, to disallow 512-bit Intel SIMD extensions:

export DRAKE_DISABLE_CPU_FEATURES=AVX512F