CODEWITHSUNDEEP
pythontensorflow
SuperCiocia
SuperCiocia

Reputation: 1971

How to force tensorflow to forget about the GPU, after it has been found?

I have a tensorflow-based code which I am running on various computers, some with CPUs and some with both CPUs & GPUs.

If a GPU is available on the machine, I would like to give the user the option of using the CPU instead.

The code from this answer works fine:

import os
import tensorflow as tf

os.environ['CUDA_VISIBLE_DEVICES'] = '-1'

if tf.test.gpu_device_name():
    print('GPU found')
else:
    print("No GPU found")

# No GPU found

However, I would like to check if a GPU is available first, and then disable it.

I tried:

import tensorflow as tf

if tf.test.gpu_device_name():
    import os
    os.environ['CUDA_VISIBLE_DEVICES'] = '-1'

if tf.test.gpu_device_name():
    print('GPU found')

# GPU found

But it does not work. Once I use tf.test.gpu_device_name(), it always remembers that the system has a GPU.

I also tried del tf, importlib.reload(tf), to no avail.
The only thing that does work is to quit the interpreter and run the first script above.

How can I make the code "forget" about the GPU once it has been found?

Upvotes: 1

Views: 2174

Answers (1)

Sraw
Sraw

Reputation: 20214

I don't understand why you need to let the TensorFlow forget. You have GPU that doesn't mean you have to use GPU.

You can use tf.device to specify the underlying device.

For example:

# Place tensors on the CPU
with tf.device('/CPU:0'):
  a = tf.constant([[1.0, 2.0, 3.0], [4.0, 5.0, 6.0]])
  b = tf.constant([[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]])

c = tf.matmul(a, b)
print(c)

So even though you have GPU, the program will still use CPU.

Upvotes: 2

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