ubantu20.04，cuda11.2安装cuda， cudann .
安装CUDNN时，如果选择 Deb安装方法，
有三个安装包要安装，必须先安装runtime版本，再安装developer版本，不然就会出现以下问题：
dpkg: dependency problems prevent configuration of libcudnn8-dev:
libcudnn8-dev depends on libcudnn8 (= 8.0.5.39-1+cuda10.1); however:
Package libcudnn8 is not installed.
dpkg: error processing package libcudnn8-dev (–install):
dependency problems - leaving unconfigured
Errors were encountered while processing:
libcudnn8-dev
安装命令：
sudo dpkg -i libcudnn8_x.x.x-1+cudax.x_amd64.deb
另外注意，在安装cudann时（nvcc- V）已经有显卡驱动了，无需再安装显卡驱动(nvidia-smi)
只需要在cudann安装完成后按提示配置~/.bashrc下的环境变量即可。
参考
- https://docs.nvidia.com/deeplearning/cudnn/install-guide/index.html#prerequisites
- https://blog.csdn.net/qq_41750952/article/details/111573098