1. install Apex
>> git clone https://github.com/NVIDIA/apex
>> cd apex
For performance and full functionality, we recommend installing Apex with CUDA and C++ extensions via
>> pip install -v --disable-pip-version-check --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./
>> pip install -v --disable-pip-version-check --no-cache-dir ./
>>./run.sh gpu1 gpu2