I have quite strange case. On new Mac (mid 2017 2,3 GHz Intel Core i5) Keras don't use all 4 cores. I run the same code on my old machine and everything is fine - CPU usage shows 300-400%.
I've read this thread but nothing helps:
K.set_session(K.tf.Session(config=K.tf.ConfigProto(intra_op_parallelism_threads=128, inter_op_parallelism_threads=128)))
or config = tf.ConfigProto(device_count={"CPU": 4})
for example i use scikit-learn on new Mac and CPu usage is more than 200-300%
my guess is that problem has connection with python version i've used 3.5 and now use 3.6, but can't understand how to solve it
UPDATE
i re-install Keras and everything works fine