Change default GPU in TensorFlow

Question

Based on the documentation, the default GPU is the one with the lowest id:

If you have more than one GPU in your system, the GPU with the lowest ID

Answer 1

Just to be clear regarding the use of the environment variable CUDA_VISIBLE_DEVICES:

To run a script my_script.py on GPU 1 only, in the Linux terminal you can use the following command:

username@server:/scratch/coding/src$ CUDA_VISIBLE_DEVICES=1 python my_script.py 

More examples illustrating the syntax:

Environment Variable Syntax      Results
CUDA_VISIBLE_DEVICES=1           Only device 1 will be seen
CUDA_VISIBLE_DEVICES=0,1         Devices 0 and 1 will be visible
CUDA_VISIBLE_DEVICES="0,1"       Same as above, quotation marks are optional
CUDA_VISIBLE_DEVICES=0,2,3       Devices 0, 2, 3 will be visible; device 1 is masked
CUDA_VISIBLE_DEVICES=""          No GPU will be visible

FYI:

• CUDA Environment Variables
• Forcing TensorFlow-GPU to use the CPU from the command line