always use non-fused op for BatchNorm inference; support NCHW for BatchRenorm

tensorpack/models/batch_norm.py

@@ -130,6 +130,14 @@ def update_bn_ema(xn, batch_mean, batch_var, moving_mean, moving_var, decay):
         return tf.identity(xn, name='output')
 
 
+def reshape_for_bn(param, ndims, chan, data_format):
+    if ndims == 2:
+        shape = [1, chan]
+    else:
+        shape = [1, 1, 1, chan] if data_format == 'NHWC' else [1, chan, 1, 1]
+    return tf.reshape(param, shape)
+
+
 @layer_register(log_shape=False)
 def BatchNorm(x, use_local_stat=None, decay=0.9, epsilon=1e-5,
               use_scale=True, use_bias=True,
@@ -168,47 +176,48 @@ def BatchNorm(x, use_local_stat=None, decay=0.9, epsilon=1e-5,
         with the official inceptionv3 example).
     """
     shape = x.get_shape().as_list()
-    assert len(shape) in [2, 4]
-    if len(shape) == 2:
-        data_format = 'NHWC'    # error using NCHW? (see #190)
+    ndims = len(shape)
+    assert ndims in [2, 4]
+    if ndims == 2:
+        data_format = 'NHWC'
     if data_format == 'NCHW':
         n_out = shape[1]
     else:
         n_out = shape[-1]  # channel
-    if len(shape) == 2:
-        x = tf.reshape(x, [-1, 1, 1, n_out])
     assert n_out is not None, "Input to BatchNorm cannot have unknown channels!"
-
     beta, gamma, moving_mean, moving_var = get_bn_variables(n_out, use_scale, use_bias, gamma_init)
 
     ctx = get_current_tower_context()
     if use_local_stat is None:
         use_local_stat = ctx.is_training
-    if use_local_stat != ctx.is_training:
+    elif use_local_stat != ctx.is_training:
         # we allow the use of local_stat in testing (only print warnings)
         # because it is useful to certain applications.
         logger.warn("[BatchNorm] use_local_stat != is_training")
 
     if use_local_stat:
+        if ndims == 2:
+            x = tf.reshape(x, [-1, 1, 1, n_out])    # fused_bn only takes 4D input
+            # fused_bn has error using NCHW? (see #190)
+
         xn, batch_mean, batch_var = tf.nn.fused_batch_norm(
             x, gamma, beta, epsilon=epsilon,
             is_training=True, data_format=data_format)
+
+        if ndims == 2:
+            xn = tf.squeeze(xn, [1, 2])
     else:
         assert not ctx.is_training, "In training, local statistics has to be used!"
-        if data_format == 'NCHW':
-            # fused is slower in inference, but support NCHW
-            xn, _, _ = tf.nn.fused_batch_norm(
-                x, gamma, beta,
-                moving_mean, moving_var,
-                epsilon=epsilon, is_training=False, data_format=data_format)
+        # non-fused op is faster for inference
+        if ndims == 4 and data_format == 'NCHW':
+            [g, b, mm, mv] = [reshape_for_bn(_, ndims, n_out, data_format)
+                              for _ in [gamma, beta, moving_mean, moving_var]]
+            xn = tf.nn.batch_normalization(x, mm, mv, b, g, epsilon)
         else:
-            xn = tf.nn.batch_normalization(     # work only for NHWC when moving_mean is a vector
+            # avoid the reshape if possible (when channel is the last dimension)
+            xn = tf.nn.batch_normalization(
                 x, moving_mean, moving_var, beta, gamma, epsilon)
 
-    if len(shape) == 2:
-        axis = [2, 3] if data_format == 'NCHW' else [1, 2]
-        xn = tf.squeeze(xn, axis)
-
     # maintain EMA only on one GPU.
     if ctx.is_main_training_tower:
         return update_bn_ema(xn, batch_mean, batch_var, moving_mean, moving_var, decay)
@@ -219,7 +228,7 @@ def BatchNorm(x, use_local_stat=None, decay=0.9, epsilon=1e-5,
 # TODO support NCHW
 @layer_register(log_shape=False)
 def BatchRenorm(x, rmax, dmax, decay=0.9, epsilon=1e-5,
-                use_scale=True, use_bias=True):
+                use_scale=True, use_bias=True, data_format='NHWC'):
     """
     Batch Renormalization layer, as described in the paper:
     `Batch Renormalization: Towards Reducing Minibatch Dependence in Batch-Normalized Models
@@ -244,10 +253,16 @@ def BatchRenorm(x, rmax, dmax, decay=0.9, epsilon=1e-5,
     """
 
     shape = x.get_shape().as_list()
-    assert len(shape) in [2, 4]
-    n_out = shape[-1]
-    if len(shape) == 2:
-        x = tf.reshape(x, [-1, 1, 1, n_out])
+    ndims = len(shape)
+    assert ndims in [2, 4]
+    if ndims == 2:
+        data_format = 'NHWC'    # error using NCHW? (see #190)
+    if data_format == 'NCHW':
+        n_out = shape[1]
+    else:
+        n_out = shape[-1]  # channel
+    assert n_out is not None, "Input to BatchRenorm cannot have unknown channels!"
+
     beta, gamma, moving_mean, moving_var = get_bn_variables(
         n_out, use_scale, use_bias, tf.constant_initializer(1.0))
 
@@ -257,21 +272,34 @@ def BatchRenorm(x, rmax, dmax, decay=0.9, epsilon=1e-5,
     # different usage comes out in the future.
 
     if use_local_stat:
-        xn, batch_mean, batch_var = tf.nn.fused_batch_norm(x, gamma, beta,
-                                                           epsilon=epsilon, is_training=True)
+        if ndims == 2:
+            x = tf.reshape(x, [-1, 1, 1, n_out])
+
+        xn, batch_mean, batch_var = tf.nn.fused_batch_norm(
+            x, gamma, beta, epsilon=epsilon, is_training=True, data_format=data_format)
+
         inv_sigma = tf.rsqrt(moving_var, 'inv_sigma')
         r = tf.stop_gradient(tf.clip_by_value(
             tf.sqrt(batch_var) * inv_sigma, 1.0 / rmax, rmax))
         d = tf.stop_gradient(tf.clip_by_value(
             (batch_mean - moving_mean) * inv_sigma,
             -dmax, dmax))
+        r = reshape_for_bn(r, ndims, n_out, data_format)
+        d = reshape_for_bn(d, ndims, n_out, data_format)
         xn = xn * r + d
+
+        if ndims == 2:
+            xn = tf.squeeze(xn, [1, 2])
+
+    else:
+        if ndims == 4 and data_format == 'NCHW':
+            [g, b, mm, mv] = [reshape_for_bn(_, ndims, n_out, data_format)
+                              for _ in [gamma, beta, moving_mean, moving_var]]
+            xn = tf.nn.batch_normalization(x, mm, mv, b, g, epsilon)
         else:
             xn = tf.nn.batch_normalization(
                 x, moving_mean, moving_var, beta, gamma, epsilon)
 
-    if len(shape) == 2:
-        xn = tf.squeeze(xn, [1, 2])
     if ctx.is_main_training_tower:
         return update_bn_ema(xn, batch_mean, batch_var, moving_mean, moving_var, decay)
     else: