一、使用conda安装

1. 安装conda（略）
2. 安装faiss

conda install -c pytorch faiss-cpu

我下载的python版本是3.9的，导致无法安装faiss，报错如下

Specifications: 
  - faiss-cpu -> python[version='>=2.7,<2.8.0a0|>=3.5,<3.6.0a0|>=3.6,<3.7.0a0|>=3.8,<3.9.0a0|>=3.7,<3.8.0a0']                                                                                                                                                                                                                                                                                                                     
Your python: python=3.9
If python is on the left-most side of the chain, that's the version you've asked for.
When python appears to the right, that indicates that the thing on the left is somehow
not available for the python version you are constrained to. Note that conda will not
change your python version to a different minor version unless you explicitly specify                                                                                                                            
that. 

对python进行降级，重新安装成功

conda install python=3.8