from six.moves import xrange # pylint: disable=redefined-builtin from datetime import datetime import math import re import time import tensorflow.python.platform import tensorflow as tf FLAGS = tf.app.flags.FLAGS tf.app.flags.DEFINE_integer('batch_size', 64, """Batch size.""") tf.app.flags.DEFINE_integer('num_batches', 100, """Number of batches to run.""") tf.app.flags.DEFINE_string('data_format', 'NCHW', """The data format for Convnet operations. Can be either NHWC or NCHW. """) tf.app.flags.DEFINE_string('train_dir', '/train_model', """Directory where to write event logs """ """and checkpoint.""") tf.app.flags.DEFINE_integer('num_gpus', 4, """How many GPUs to use.""") tf.app.flags.DEFINE_boolean('log_device_placement', False, """Whether to log device placement.""") NUM_EXAMPLES_PER_EPOCH_FOR_TRAIN = 50000 NUM_EPOCHS_PER_DECAY = 50 INITIAL_LEARNING_RATE = 0.1 LEARNING_RATE_DECAY_FACTOR = 0.1 TOWER_NAME = 'tower' def _conv(name, inpOp, nIn, nOut, kH, kW, dH, dW, padType, wd=0.005): with tf.name_scope(name) as scope: kernel = tf.get_variable( name + '_w', [kH, kW, nIn, nOut], initializer=tf.truncated_normal_initializer( stddev=0.01, dtype=tf.float32), dtype=tf.float32) if wd is not None: weight_decay = tf.mul(tf.nn.l2_loss(kernel), wd, name='weight_loss') tf.add_to_collection('losses', weight_decay) if FLAGS.data_format == 'NCHW': strides = [1, 1, dH, dW] else: strides = [1, dH, dW, 1] conv = tf.nn.conv2d( inpOp, kernel, strides, padding=padType, data_format=FLAGS.data_format) biases = tf.get_variable( name=name + '_b', shape=[nOut], initializer=tf.constant_initializer( value=0.0, dtype=tf.float32), dtype=tf.float32) bias = tf.reshape( tf.nn.bias_add( conv, biases, data_format=FLAGS.data_format), conv.get_shape()) conv1 = tf.nn.relu(bias, name=scope) return conv1 def _affine(name, inpOp, nIn, nOut, wd=0.005, act=True): with tf.name_scope(name) as scope: kernel = tf.get_variable( name + '_w', [nIn, nOut], initializer=tf.truncated_normal_initializer( stddev=0.01, dtype=tf.float32), dtype=tf.float32) if wd is not None: weight_decay = tf.mul(tf.nn.l2_loss(kernel), wd, name='weight_loss') tf.add_to_collection('losses', weight_decay) biases = tf.get_variable( name + '_b', [nOut], initializer=tf.constant_initializer( value=0.0, dtype=tf.float32), dtype=tf.float32, trainable=True) affine1 = tf.nn.relu_layer(inpOp, kernel, biases, name=name) if act else \ tf.matmul(inpOp, kernel) + biases return affine1 def _mpool(name, inpOp, kH, kW, dH, dW): if FLAGS.data_format == 'NCHW': ksize = [1, 1, kH, kW] strides = [1, 1, dH, dW] else: ksize = [1, kH, kW, 1] strides = [1, dH, dW, 1] return tf.nn.max_pool( inpOp, ksize=ksize, strides=strides, padding='VALID', data_format=FLAGS.data_format, name=name) def _norm(name, l_input, lsize=4): return tf.nn.lrn(l_input, lsize, bias=1.0, alpha=0.001 / 9.0, beta=0.75, name=name) def loss(logits, labels): labels = tf.cast(labels, tf.int64) cross_entropy = tf.nn.sparse_softmax_cross_entropy_with_logits( logits, labels, name='cross_entropy_per_example') cross_entropy_mean = tf.reduce_mean(cross_entropy, name='cross_entropy') tf.add_to_collection('losses', cross_entropy_mean) # The total loss is defined as the cross entropy loss plus all of the weight # decay terms (L2 loss). return tf.add_n(tf.get_collection('losses'), name='total_loss') def get_incoming_shape(incoming): """ Returns the incoming data shape """ if isinstance(incoming, tf.Tensor): return incoming.get_shape().as_list() elif type(incoming) in [np.array, list, tuple]: return np.shape(incoming) else: raise Exception("Invalid incoming layer.") def inference(images): conv1 = _conv('conv1', images, 3, 96, 11, 11, 4, 4, 'VALID') pool1 = _mpool('pool1', conv1, 3, 3, 2, 2) norm1 = _norm('norm1', pool1, lsize=5) conv2 = _conv('conv2', norm1, 96, 256, 5, 5, 1, 1, 'SAME') pool2 = _mpool('pool2', conv2, 3, 3, 2, 2) norm2 = _norm('norm2', pool2, lsize=5) conv3 = _conv('conv3', norm2, 256, 384, 3, 3, 1, 1, 'SAME') conv4 = _conv('conv4', conv3, 384, 384, 3, 3, 1, 1, 'SAME') conv5 = _conv('conv5', conv4, 384, 256, 3, 3, 1, 1, 'SAME') pool5 = _mpool('pool5', conv5, 3, 3, 2, 2) resh1 = tf.reshape(pool5, [-1, 256 * 6 * 6]) affn1 = _affine('fc6', resh1, 256 * 6 * 6, 4096) affn2 = _affine('fc7', affn1, 4096, 4096) affn3 = _affine('fc8', affn2, 4096, 1000, wd=None, act=False) # last fc return affn3 def tower_loss(scope): """Calculate the total loss on a single tower running the model. Args: scope: unique prefix string identifying the tower, e.g. 'tower_0' Returns: Tensor of shape [] containing the total loss for a batch of data """ image_size = 224 if FLAGS.data_format == 'NCHW': image_shape = [FLAGS.batch_size, 3, image_size + 3, image_size + 3] else: image_shape = [FLAGS.batch_size, image_size + 3, image_size + 3, 3] images = tf.get_variable( 'image', image_shape, initializer=tf.truncated_normal_initializer( stddev=0.1, dtype=tf.float32), dtype=tf.float32, trainable=False) labels = tf.get_variable( 'label', [FLAGS.batch_size], initializer=tf.constant_initializer(1), dtype=tf.int32, trainable=False) # Build a Graph that computes the logits predictions from the # inference model. last_layer = inference(images) # Build the portion of the Graph calculating the losses. Note that we will # assemble the total_loss using a custom function below. _ = loss(last_layer, labels) # Assemble all of the losses for the current tower only. losses = tf.get_collection('losses', scope) # Calculate the total loss for the current tower. total_loss = tf.add_n(losses, name='total_loss') # Compute the moving average of all individual losses and the total loss. loss_averages = tf.train.ExponentialMovingAverage(0.9, name='avg') loss_averages_op = loss_averages.apply(losses + [total_loss]) # Attach a scalar summary to all individual losses and the total loss; do the # same for the averaged version of the losses. for l in losses + [total_loss]: # Remove 'tower_[0-9]/' from the name in case this is a multi-GPU training # session. This helps the clarity of presentation on tensorboard. loss_name = re.sub('%s_[0-9]*/' % TOWER_NAME, '', l.op.name) # Name each loss as '(raw)' and name the moving average version of the loss # as the original loss name. tf.scalar_summary(loss_name + ' (raw)', l) tf.scalar_summary(loss_name, loss_averages.average(l)) with tf.control_dependencies([loss_averages_op]): total_loss = tf.identity(total_loss) return total_loss def average_gradients(tower_grads): """Calculate the average gradient for each shared variable across all towers. Note that this function provides a synchronization point across all towers. Args: tower_grads: List of lists of (gradient, variable) tuples. The outer list is over individual gradients. The inner list is over the gradient calculation for each tower. Returns: List of pairs of (gradient, variable) where the gradient has been averaged across all towers. """ average_grads = [] for grad_and_vars in zip(*tower_grads): # Note that each grad_and_vars looks like the following: # ((grad0_gpu0, var0_gpu0), ... , (grad0_gpuN, var0_gpuN)) grads = [] for g, _ in grad_and_vars: # Add 0 dimension to the gradients to represent the tower. expanded_g = tf.expand_dims(g, 0) # Append on a 'tower' dimension which we will average over below. grads.append(expanded_g) # Average over the 'tower' dimension. grad = tf.concat(0, grads) grad = tf.reduce_mean(grad, 0) # Keep in mind that the Variables are redundant because they are shared # across towers. So .. we will just return the first tower's pointer to # the Variable. v = grad_and_vars[0][1] grad_and_var = (grad, v) average_grads.append(grad_and_var) return average_grads def time_tensorflow_run(session, target): num_steps_burn_in = 50 total_duration = 0.0 total_duration_squared = 0.0 for i in xrange(FLAGS.num_batches + num_steps_burn_in): start_time = time.time() _, loss_value = session.run(target) duration = time.time() - start_time if i > num_steps_burn_in: if not i % 10: num_examples_per_step = FLAGS.batch_size * FLAGS.num_gpus examples_per_sec = num_examples_per_step / duration sec_per_batch = duration format_str = ( '%s: step %d, loss = %.2f (%.1f examples/sec; %.3f ' 'sec/batch batch_size = %d)') print(format_str % (datetime.now(), i - num_steps_burn_in, loss_value, duration, sec_per_batch, num_examples_per_step)) total_duration += duration total_duration_squared += duration * duration mn = total_duration / FLAGS.num_batches vr = total_duration_squared / FLAGS.num_batches - mn * mn sd = math.sqrt(vr) print('%s: FwdBwd across %d steps, %.3f +/- %.3f sec / batch' % (datetime.now(), FLAGS.num_batches, mn, sd)) def run_benchmark(): with tf.Graph().as_default(), tf.device('/cpu:0'): # Create a variable to count the number of train() calls. This equals the # number of batches processed * FLAGS.num_gpus. global_step = tf.get_variable( 'global_step', [], initializer=tf.constant_initializer(0), trainable=False) # Calculate the learning rate schedule. num_batches_per_epoch = (NUM_EXAMPLES_PER_EPOCH_FOR_TRAIN / FLAGS.batch_size) decay_steps = int(num_batches_per_epoch * NUM_EPOCHS_PER_DECAY) # Decay the learning rate exponentially based on the number of steps. lr = tf.train.exponential_decay( INITIAL_LEARNING_RATE, global_step, decay_steps, LEARNING_RATE_DECAY_FACTOR, staircase=True) # Create an optimizer that performs gradient descent. opt = tf.train.MomentumOptimizer(lr, 0.9) # Calculate the gradients for each model tower. tower_grads = [] for i in xrange(FLAGS.num_gpus): with tf.device('/gpu:%d' % i): with tf.name_scope('%s_%d' % (TOWER_NAME, i)) as scope: # Calculate the loss for one tower of the model. This function # constructs the entire model but shares the variables across # all towers. loss = tower_loss(scope) # Reuse variables for the next tower. tf.get_variable_scope().reuse_variables() # Retain the summaries from the final tower. summaries = tf.get_collection(tf.GraphKeys.SUMMARIES, scope) # Calculate the gradients for the batch of data on this tower. grads = opt.compute_gradients(loss) # Keep track of the gradients across all towers. tower_grads.append(grads) # We must calculate the mean of each gradient. Note that this is the # synchronization point across all towers. grads = average_gradients(tower_grads) # Apply the gradients to adjust the shared variables. apply_gradient_op = opt.apply_gradients(grads, global_step=global_step) # Group all updates to into a single train op. train_op = tf.group(apply_gradient_op) # Build an initialization operation. init = tf.initialize_all_variables() # Start running operations on the Graph. allow_soft_placement must be set to # True to build towers on GPU, as some of the ops do not have GPU # implementations. sess = tf.Session(config=tf.ConfigProto( allow_soft_placement=True, log_device_placement=FLAGS.log_device_placement)) sess.run(init) time_tensorflow_run(sess, [train_op, loss]) def main(_): run_benchmark() if __name__ == '__main__': tf.app.run()