GPU

import tensorflow as tf
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)