pwcm

A minimal working example of C++ function multiversioning in Python wheels.

Date: 2017-02-18
Version: 0.0.1
Developer: Alberto Pettarin
License: the MIT License (MIT)
Contact: click here

Overview

This repository contains a simple Python 2.7/3.5+ package named pwcm that has a C++ extension (pwcm.cext) containing function multiversioning. See also this article.

The basic goal consists in testing the possibility of creating a single Python wheel supporting CPUs with different features, e.g. SSE3 vs SSE4.1/SSE4.2 vs AVX. See this PyTorch issue.

So far, it seems to work as expected:

Machine	CPU	Flags	pwcm Output	Correct?	Compiler	Date
laptop1	Intel(R) Core(TM) i5-6200U	SSE4.2	SSE4.2	Y	GCC 6	2017-02-18
vps1	AMD Athlon(tm) II X2 240	SSE4a	SSE4a	Y	GCC 6	2017-02-18

Installation from source

$ virtualenv venv
$ cd venv
$ source bin/activate
$ git clone https://github.com/pettarin/pwcm
$ cd pwcm
$ make test
$ deactivate

The last line of the output should be something like:

[INFO] C++ extension returned the known value: SSE4.2

Create a Python wheel

$ # in the pwcm root directory, the one containing README.md
$ make wheel
$ # look inside the dist directory
$ # the name of the .whl file depends on your Python version
$ ls dist
pwcm-0.0.1-cp27-cp27mu-linux_x86_64.whl

Installation from a wheel file

$ # create a new virtualenv
$ virtualenv venvtest
$ cd venvtest
$ source bin/activate
$ # download/copy the .whl file here
$ # adjust the name depending on your platform
$ pip install pwcm-0.0.1-cp27-cp27mu-linux_x86_64.whl
$ python -m pwcm
$ deactivate

Again, python -m pwcm should print something like:

[INFO] C++ extension returned the known value: SSE4.2

Clean

$ # in the pwcm root directory, the one containing README.md
$ make clean
$ # in case you installed with pip
$ pip uninstall pwcm

License

The contents of this repository are released under the terms of the MIT License.