Introduce avx512 optimization mode and FAISS_OPT_LEVEL env variable

[alexanderguzhva]

Enables avx512 optimized code (AVX512 subsets F, CD, VL, DQ and BW, which are available for Intel Skylake+ and all AMD Zen4).
Also, introduces FAISS_OPT_LEVEL environment variable. Set it to AVX2, AVX512 or empty to pick the appropriate x86_64 instruction set.

Compiled via the following

cmake -B build -DCMAKE_BUILD_TYPE=Release -DFAISS_ENABLE_GPU=OFF -DFAISS_OPT_LEVEL=avx512 -DBUILD_TESTING=ON .
make -C build -j 8 faiss_test
make -C build -j 8 swigfaiss
make -C build -j 8 swigfaiss_avx2
make -C build -j 8 swigfaiss_avx512
cd build/faiss/python
python3 setup.py build
python3 setup.py install --force

Now, running the following script 1.py

import logging
logging.basicConfig(level=logging.DEBUG)

import faiss

produces the following:

root@6179abeef23c:~/faiss# LOGLEVEL=DEBUG FAISS_OPT_LEVEL= python3 1.py
DEBUG:faiss.loader:Using  as an instruction set.
INFO:faiss.loader:Loading faiss.
INFO:faiss.loader:Successfully loaded faiss.
root@6179abeef23c:~/faiss# LOGLEVEL=DEBUG FAISS_OPT_LEVEL=AVX2 python3 1.py
DEBUG:faiss.loader:Using AVX2 as an instruction set.
INFO:faiss.loader:Loading faiss with AVX2 support.
INFO:faiss.loader:Successfully loaded faiss with AVX2 support.
root@6179abeef23c:~/faiss# LOGLEVEL=DEBUG FAISS_OPT_LEVEL=AVX512 python3 1.py
DEBUG:faiss.loader:Using AVX512 as an instruction set.
INFO:faiss.loader:Loading faiss with AVX512 support.
INFO:faiss.loader:Successfully loaded faiss with AVX512 support.
root@6179abeef23c:~/faiss# LOGLEVEL=DEBUG python3 1.py
DEBUG:faiss.loader:Environment variable FAISS_OPT_LEVEL is not set, so let's pick the instruction set according to the current CPU
INFO:faiss.loader:Loading faiss with AVX512 support.
INFO:faiss.loader:Successfully loaded faiss with AVX512 support.

[mdouze]

You probably added faiss/python/swigfaiss_avx512.swig by mistake

• please add a flag to get_compile_options()

faiss/faiss/utils/utils.cpp

Line 109 in 90654d6

std::string get_compile_options() {

Maybe add an env variable FAISS_OPT_LEVEL that overrides the switching code between the capabilities, then we can run the test suite for the 3 opt levels (but that can be done in a subsequent diff).

[alexanderguzhva]

@mdouze done, including FAISS_OPT_LEVEL. And you're correct, I've missed swigfaiss_avx512.swig

[alexanderguzhva]

do not merge, 1 more change is needed

[alexanderguzhva]

good to go

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@mdouze has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@mdouze merged this pull request in eefa391.