How to set Torch to use only one gpu when there are two gpu?

Question

My computer has two GPUs. And this is my first time using two GPUs. When I had one GPU, I just run the Cuda program, and it runs on the only one GPU. However, I don't know how to control the program to use which GPU and how to run program on the only one GPU. I searched the Internet and post says

export CUDA_VISIBLE_DEVICES=0

This must be used before run the program. I have two program to run. The one is torch script and the other is Cuda script. I opened two terminals and in the 1st terminal, I used the command above and run the torch program. After that, in the 2nd terminal, I also used the command above by only changing the number from 0 to 1 and run the cuda program.

However, seeing the picture of nvidia-smi, it shows the two programs are assigned to the 0th GPU. I wanted to assigned torch program(PID 19520) to the 0th and the cuda program(PID 20351) to the 1st GPU.

How can I assign the two program to different GPU devices?

The followings are the settings of the torch script. (Ubuntu 14.04, nvidia titan gtx x, cuda-7.5)

--[[command line arguments]]--
cmd = torch.CmdLine()
cmd:text()
cmd:text('Train a Recurrent Model for Visual Attention')
cmd:text('Example:')
cmd:text('$> th rnn-visual-attention.lua > results.txt')
cmd:text('Options:')
cmd:option('--learningRate', 0.01, 'learning rate at t=0')
cmd:option('--minLR', 0.00001, 'minimum learning rate')
cmd:option('--saturateEpoch', 800, 'epoch at which linear decayed LR will reach minLR')
cmd:option('--momentum', 0.9, 'momentum')
cmd:option('--maxOutNorm', -1, 'max norm each layers output neuron weights')
cmd:option('--cutoffNorm', -1, 'max l2-norm of contatenation of all gradParam tensors')
cmd:option('--batchSize', 20, 'number of examples per batch')
cmd:option('--cuda', true, 'use CUDA')
cmd:option('--useDevice', 1, 'sets the device (GPU) to use')
cmd:option('--maxEpoch', 2000, 'maximum number of epochs to run')
cmd:option('--maxTries', 100, 'maximum number of epochs to try to find a better local minima for early-stopping')
cmd:option('--transfer', 'ReLU', 'activation function')
cmd:option('--uniform', 0.1, 'initialize parameters using uniform distribution between -uniform and uniform. -1 means default initialization')
cmd:option('--xpPath', '', 'path to a previously saved model')
cmd:option('--progress', false, 'print progress bar')
cmd:option('--silent', false, 'dont print anything to stdout')

Answer 1

CUDA_VISIBLE_DEVICES=0 th [torch script]
CUDA_VISIBLE_DEVICES=1 [CUDA script]