How to set env variable MXNET_CUDNN_AUTOTUNE_DEFAULT to 0?

Actually I don’t know how to name the topic. After I compile mxnet, I run a script and terminal shows

src/operator/nn/./cudnn/./cudnn_algoreg-inl.h:97: Running performance tests to find the best convolution algorithm, this can take a while… (setting env variable MXNET_CUDNN_AUTOTUNE_DEFAULT to 0 to disable)

, then it doesn’t process anything later (but it doesn’t shut down).

I don’t know how to set env variable MXNET_CUDNN_AUTOTUNE_DEFAULT to 0. Maybe this problem has no relation with MXNET_CUDNN_AUTOTUNE_DEFAULT. Could anyone help me?