官方安装
### Linux
For performance and full functionality, we recommend installing Apex with
CUDA and C++ extensions via （全部功能）
```bash
git clone https://github.com/NVIDIA/apex
cd apex
pip install -v --disable-pip-version-check --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./
```
Apex also supports a Python-only build via （部分功能）
```bash
pip install -v --disable-pip-version-check --no-cache-dir ./
```
A Python-only build omits:
- Fused kernels required to use `apex.optimizers.FusedAdam`.
- Fused kernels required to use `apex.normalization.FusedLayerNorm` and `apex.normalization.FusedRMSNorm`.
- Fused kernels that improve the performance and numerical stability of `apex.parallel.SyncBatchNorm`.
- Fused kernels that improve the performance of `apex.parallel.DistributedDataParallel` and `apex.amp`.
`DistributedDataParallel`, `amp`, and `SyncBatchNorm` will still be usable, but they may be slower.
Pyprof support has been moved to its own [dedicated repository](https://github.com/NVIDIA/PyProf).
Pyprof is deprecated in Apex and the pyprof directory will be removed by the end of June 2022.
### [Experimental] Windows
`pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" .` may work if you were able to build Pytorch from source
on your system. A Python-only build via `pip install -v --no-cache-dir .` is more likely to work.
If you installed Pytorch in a Conda environment, make sure to install Apex in that same environment.安装apex
git clone https://github.com/NVIDIA/apex
cd apex
pip install -v --disable-pip-version-check --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./
错误
UserWarning: Disabling all use of wheels due to the use of --build-option / --global-option / -- install-option. cmdoptions.check_install_build_global(options)
原因是 pip install -v --disable-pip-version-check --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./ （中的./ 没有复制上）