配置环境变量：export CUDA_CACHE_MAXSIZE=2147483648
默认情况下，不配置是256MB，有些时候，会出现警告（开大缓存，第一次慢点，后续会好点）：
gpu_device.cc:2431] TensorFlow was not built with CUDA kernel binaries compatible with compute capability 12.0. CUDA kernels will be jit-compiled from PTX, which could take 30 minutes or longer.