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CPUFeature

CPUFeature is a tool for detecting CPU features on x86/AMD64 processors. In particular it is engineered to have very low overhead on import (~ 1 ms) and to detect features that are often important in high-performance computing where hybrid combinations of multi-threading and multi-processing are used. Detects CPU features such as:

  • SIMD instruction support
  • Number of cores (both virtual and physical)
  • Number of CPUs on the motherboard.
  • Cache sizes

It is written in C99. It supports Windows with MSVC and Linux with GCC/LLVM compilers. MacOSX should also work with GCC/LLVM. CPUFeature is licensed under Creative Commons Zero, so it may be freely incorporated as a submodule into your own projects.

CPUFeature is considered to be in an alpha state because while it is tested via GitHub Actions on a variety of platforms, we expect edge cases to appear.

Warning

As CPUFeature uses the cpuid instruction, its behavior in the case of virtualization or containerization is undefined. Whether or not it returns fully or partially correct information will depend on the implementation of the cpuid function by the virtual machine. Test before trusting the results.

Example

The module generates a dict called CPUFeature on import which contains useful information regarding optimization and compilation for the host. For my Intel i7-7820X Skylake CPU, it generates the following info:

    > python -c "import cpufeature; cpufeature.print_features()"
  === CPU FEATURES ===
      VendorId                : GenuineIntel
      num_virtual_cores       : 16
      num_physical_cores      : 8
      num_threads_per_core    : 2
      num_cpus                : 1
      cache_line_size         : 64
      cache_L1_size           : 32768
      cache_L2_size           : 1048576
      cache_L3_size           : 11534336
      OS_x64                  : True
      OS_AVX                  : True
      OS_AVX512               : True
      MMX                     : True
      x64                     : True
      ABM                     : True
      RDRAND                  : True
      BMI1                    : True
      BMI2                    : True
      ADX                     : True
      PREFETCHWT1             : False
      MPX                     : True
      SSE                     : True
      SSE2                    : True
      SSE3                    : True
      SSSE3                   : True
      SSE4.1                  : True
      SSE4.2                  : True
      SSE4.a                  : False
      AES                     : True
      SHA                     : False
      AVX                     : True
      XOP                     : False
      FMA3                    : True
      FMA4                    : False
      AVX2                    : True
      AVX512f                 : True
      AVX512pf                : False
      AVX512er                : False
      AVX512cd                : True
      AVX512vl                : True
      AVX512bw                : True
      AVX512dq                : True
      AVX512ifma              : False
      AVX512vbmi              : False
      AVX512vbmi2             : False
      AVX512vnni              : False

Notes on Fields

  • If num_threads_per_core > 1 likely Intel Hyperthreading (or equivalent architecture) is present. The physical core count may be unreliable in virtual environments.
  • Cache sizes are in bytes.
  • For AVX2, check AVX2 and OS_AVX2.
  • For AVX512, check AVX512f and OS_AVX512. Python support for AVX512 instructions is highly limited outside of compilation with ICC. MSVC does not have AVX512 support until MSVC2017.

Authors

  • Based on FeatureDetector by Alexander Yee (https://github.com/Mysticial/FeatureDetector).
  • Ported to Python by Robert A. McLeod, who added detection of cores, and cache sizes.
  • drfinkus contributed to AMD support.
  • WidgetA contributed support for compilation with Clang.

Release Notes

0.2.2

Under Development

0.2.1

  • Supported Python versions are now 3.8 - 3.11.
  • Added tests for AVX512vbmi2 and AVX512vnni.

0.2.0

  • Added pre-build wheels via cibuildwheels and GitHub Actions for Python 3.6-3.9 on Linux/Windows/MacOSX.
  • Added support for AMD processors.
  • Added a script for valgrind to more easier locate problems when the module crashes.

0.1.1

  • Fixes for compilation with clang.

0.1.0

  • Added detection of processors, cores, and cache sizes
  • Created Python wrapper around FeatureDetector
  • Reduced FeatureDetector to C99 for better cross-platform compatibility