How can I use GPU to speed up the process?

[Chen65010445]

When I train the model the lines below would show up:
2017-10-25 21:03:30.854048: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.1 instructions, but these are available on your machine and could speed up CPU computations.
2017-10-25 21:03:30.854067: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.2 instructions, but these are available on your machine and could speed up CPU computations.
2017-10-25 21:03:30.854071: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use AVX instructions, but these are available on your machine and could speed up CPU computations.
2017-10-25 21:03:30.854074: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use AVX2 instructions, but these are available on your machine and could speed up CPU computations.
2017-10-25 21:03:30.854077: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use FMA instructions, but these are available on your machine and could speed up CPU computations.
But I don't want to use CPU to do the computations how could I change this situation?

[vanhuyz]

Please check out this issue tensorflow/tensorflow#7778.
Simply just ignore those warnings.
If you set up your GPU correctly, TensorFlow will use it by default.
You can check https://stackoverflow.com/questions/38009682/how-to-tell-if-tensorflow-is-using-gpu-acceleration-from-inside-python-shell to make sure.

[sak797]

When I train I could use 1 GPU, can you please explain the process of using multiple GPU's