Thanks for your reply.
According to your answer, there is a misunderstanding of cuda installation in my prior description. I thought cudatoolkit=9.2 means the installed pytorch is pre-compiled with cudatoolkit=9.2. However, it should be that it will install cudatoolkit 9.2. Base on this PyTorch Forum Discussion, it also means it will not only install a cudatoolkit, but also install a corresponding version of CuDNN.
So, my question is that,
Is this cudatoolkit and cuDNN installation in our conda environment solely or it is system-wide?