下面的代码段应该给出tensorflow可用的所有设备。

from tensorflow.python.client import device_lib
print(device_lib.list_local_devices())

样例输出 (名字:“/ cpu: 0” device_type:“CPU” memory_limit: 268435456 位置{ ｝ 化身:4402277519343584096, 名称:“/ gpu: 0” device_type:“GPU” memory_limit: 6772842168 位置{ bus_id: 1 ｝ 化身:7471795903849088328 physical_device_desc: "设备:0，名称:GeForce GTX 1070, pci总线id: 0000:05:00.0" ］

你可以通过运行下面的代码来检查你是否正在使用GPU:

import tensorflow as tf
tf.test.gpu_device_name()

如果输出是“，这意味着你只使用CPU; 如果输出类似于/device:GPU:0，这意味着GPU工作。

并使用下面的代码来检查您使用的GPU:

from tensorflow.python.client import device_lib 
device_lib.list_local_devices()

我更喜欢使用nvidia-smi来监控GPU使用情况。如果当你开始你的程序时，它显著上升，这是一个强烈的迹象，表明你的张量流正在使用GPU。

>>> import tensorflow as tf 
>>> tf.config.list_physical_devices('GPU')

2020-05-10 14:58:16.243814: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcuda.so.1
2020-05-10 14:58:16.262675: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:981] successful NUMA node read from SysFS had negative value (-1), but there must be at least one NUMA node, so returning NUMA node zero
2020-05-10 14:58:16.263119: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1555] Found device 0 with properties:
pciBusID: 0000:01:00.0 name: GeForce GTX 1060 6GB computeCapability: 6.1
coreClock: 1.7715GHz coreCount: 10 deviceMemorySize: 5.93GiB deviceMemoryBandwidth: 178.99GiB/s
2020-05-10 14:58:16.263143: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcudart.so.10.1
2020-05-10 14:58:16.263188: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcublas.so.10
2020-05-10 14:58:16.264289: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcufft.so.10
2020-05-10 14:58:16.264495: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcurand.so.10
2020-05-10 14:58:16.265644: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcusolver.so.10
2020-05-10 14:58:16.266329: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcusparse.so.10
2020-05-10 14:58:16.266357: I tensorflow/stream_executor/platform/default/dso_loader.cc:44] Successfully opened dynamic library libcudnn.so.7
2020-05-10 14:58:16.266478: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:981] successful NUMA node read from SysFS had negative value (-1), but there must be at least one NUMA node, so returning NUMA node zero
2020-05-10 14:58:16.266823: I tensorflow/stream_executor/cuda/cuda_gpu_executor.cc:981] successful NUMA node read from SysFS had negative value (-1), but there must be at least one NUMA node, so returning NUMA node zero
2020-05-10 14:58:16.267107: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1697] Adding visible gpu devices: 0
[PhysicalDevice(name='/physical_device:GPU:0', device_type='GPU')]

正如@AmitaiIrron所建议的:

这个部分表示找到了一个gpu

2020-05-10 14:58:16.263119: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1555] Found device 0 with properties:

pciBusID: 0000:01:00.0 name: GeForce GTX 1060 6GB computeCapability: 6.1
coreClock: 1.7715GHz coreCount: 10 deviceMemorySize: 5.93GiB deviceMemoryBandwidth: 178.99GiB/s

这里它被添加为一个可用的物理设备

2020-05-10 14:58:16.267107: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1697] Adding visible gpu devices: 0

[PhysicalDevice(name='/physical_device:GPU:0', device_type='GPU')]

除了使用sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))，这是在其他答案和官方TensorFlow文档中列出的，你可以尝试给gpu分配一个计算，看看你是否有错误。

import tensorflow as tf
with tf.device('/gpu:0'):
    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)

with tf.Session() as sess:
    print (sess.run(c))

在这里

"/cpu:0":您机器的cpu。 "/gpu:0":你机器的gpu，如果你有的话。

如果你有一个gpu并且可以使用它，你会看到结果。否则，您将看到一个带有很长的堆栈跟踪的错误。最后你会得到这样的结果:

无法将设备分配给节点“MatMul”:无法满足显式要求 设备规格'/device:GPU:0'因为没有设备与之匹配 规范是在这个过程中注册的

最近在TF中出现了几个有用的函数:

tf.test。Is_gpu_available表示gpu是否可用 tf.test。Gpu_device_name返回gpu设备名称

你也可以检查会话中可用的设备:

with tf.Session() as sess:
  devices = sess.list_devices()

设备会给你一些类似的东西

[_DeviceAttributes(/job:tpu_worker/replica:0/task:0/device:CPU:0, CPU, -1, 4670268618893924978),
 _DeviceAttributes(/job:tpu_worker/replica:0/task:0/device:XLA_CPU:0, XLA_CPU, 17179869184, 6127825144471676437),
 _DeviceAttributes(/job:tpu_worker/replica:0/task:0/device:XLA_GPU:0, XLA_GPU, 17179869184, 16148453971365832732),
 _DeviceAttributes(/job:tpu_worker/replica:0/task:0/device:TPU:0, TPU, 17179869184, 10003582050679337480),
 _DeviceAttributes(/job:tpu_worker/replica:0/task:0/device:TPU:1, TPU, 17179869184, 5678397037036584928)

这应该会给出Tensorflow可用的设备列表(Py-3.6下):

tf = tf.Session(config=tf.ConfigProto(log_device_placement=True))
tf.list_devices()
# _DeviceAttributes(/job:localhost/replica:0/task:0/device:CPU:0, CPU, 268435456)