我有一台拥有3x 1080 GPU的机器。以下是培训代码：
dynamic_learning_rate = tf.placeholder(tf.float32, shape=[])
model_version = tf.constant(1, tf.int32)
with tf.device('/cpu:0'):
with tf.name_scope('Input'):
# Input images and labels.
batch_images,\
batch_input_vectors,\
batch_one_hot_labels,\
batch_file_paths,\
batch_labels = self.get_batch()
grads = []
pred = []
cost = []
# Define optimizer
optimizer = tf.train.MomentumOptimizer(learning_rate=dynamic_learning_rate / self.batch_size,
momentum=0.9,
use_nesterov=True)
split_input_image = tf.split(batch_images, self.num_gpus)
split_input_vector = tf.split(batch_input_vectors, self.num_gpus)
split_input_one_hot_label = tf.split(batch_one_hot_labels, self.num_gpus)
for i in range(self.num_gpus):
with tf.device(tf.DeviceSpec(device_type="GPU", device_index=i)):
with tf.variable_scope(tf.get_variable_scope(), reuse=i > 0):
with tf.name_scope('Model'):
# Construct model
with tf.variable_scope("inference"):
tower_pred = self.model(split_input_image[i], split_input_vector[i], is_training=True)
pred.append(tower_pred)
with tf.name_scope('Loss'):
# Define loss and optimizer
softmax_cross_entropy_cost = tf.reduce_mean(
tf.nn.softmax_cross_entropy_with_logits(logits=tower_pred, labels=split_input_one_hot_label[i]))
cost.append(softmax_cross_entropy_cost)
# Concat variables
pred = tf.concat(pred, 0)
cost = tf.reduce_mean(cost)
# L2 regularization
trainable_vars = tf.trainable_variables()
l2_regularization = tf.add_n(
[tf.nn.l2_loss(v) for v in trainable_vars if any(x in v.name for x in ['weights', 'biases'])])
for v in trainable_vars:
if any(x in v.name for x in ['weights', 'biases']):
print(v.name + ' - included for L2 regularization!')
else:
print(v.name)
cost = cost + self.l2_regularization_strength*l2_regularization
with tf.name_scope('Accuracy'):
# Evaluate model
correct_pred = tf.equal(tf.argmax(pred, 1), tf.argmax(batch_one_hot_labels, 1))
accuracy = tf.reduce_mean(tf.cast(correct_pred, tf.float32))
prediction = tf.nn.softmax(pred, name='softmax')
# Creates a variable to hold the global_step.
global_step = tf.Variable(0, trainable=False, name='global_step')
# Minimization
update = optimizer.minimize(cost, global_step=global_step, colocate_gradients_with_ops=True)
我参加培训后：
Fri Nov 10 12:28:00 2017
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 384.90 Driver Version: 384.90 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 1080 Off | 00000000:03:00.0 Off | N/A |
| 42% 65C P2 62W / 198W | 7993MiB / 8114MiB | 100% Default |
+-------------------------------+----------------------+----------------------+
| 1 GeForce GTX 1080 Off | 00000000:04:00.0 Off | N/A |
| 33% 53C P2 150W / 198W | 7886MiB / 8114MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
| 2 GeForce GTX 1080 Off | 00000000:05:00.0 On | N/A |
| 26% 54C P2 170W / 198W | 7883MiB / 8108MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
+-----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 23228 C python 7982MiB |
| 1 23228 C python 7875MiB |
| 2 4793 G /usr/lib/xorg/Xorg 40MiB |
| 2 23228 C python 7831MiB |
+-----------------------------------------------------------------------------+
Fri Nov 10 12:28:36 2017
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 384.90 Driver Version: 384.90 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 1080 Off | 00000000:03:00.0 Off | N/A |
| 42% 59C P2 54W / 198W | 7993MiB / 8114MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
| 1 GeForce GTX 1080 Off | 00000000:04:00.0 Off | N/A |
| 33% 57C P2 154W / 198W | 7886MiB / 8114MiB | 100% Default |
+-------------------------------+----------------------+----------------------+
| 2 GeForce GTX 1080 Off | 00000000:05:00.0 On | N/A |
| 27% 55C P2 155W / 198W | 7883MiB / 8108MiB | 100% Default |
+-------------------------------+----------------------+----------------------+
+-----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 23228 C python 7982MiB |
| 1 23228 C python 7875MiB |
| 2 4793 G /usr/lib/xorg/Xorg 40MiB |
| 2 23228 C python 7831MiB |
+-----------------------------------------------------------------------------+
您会看到第一个GPU运行时，其他两个GPU将处于空闲状态，反之亦然。备用频率约为0.5秒。
对于单个GPU，训练速度在650 [images/second]附近，
所有3个GPU我只得到1050 [images/second]。
对这个问题有什么看法吗？
您需要确保所有可训练变量都在控制器设备（通常是CPU）上，并且所有其他工作设备（通常是GPU）并行使用CPU中的变量。