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

As is stated in the documentation, you can use tf.device('/gpu:id') to specify a device other than the default.

# This will use the second GPU on your system
with tf.device('/gpu:1'):
    a = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[2, 3], name='a')
    b = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[3, 2], name='b')

c = tf.matmul(a, b)
sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))
print sess.run(c)