There are two Nvidia graphics cards installed on my machine. When I execute:

cd ..

(now you are in caffe-master directory)

make all

make test

make runtest

The run test stuck at TestRMSPropLeastSquaresUpdateWithRmsDecay. According to link here, it is due to multi-GPUs. The fix is to set this before execution of runtest:

export CUDA_VISIBLE_DEVICES=0