Support fp16 training for ResNeXt101_32x4d (#653)

configs/ResNeXt/ResNeXt101_32x4d_fp16.yaml

+mode: 'train'
+ARCHITECTURE:
+    name: 'ResNeXt101_32x4d'
+
+pretrained_model: ""
+model_save_dir: "./output/"
+classes_num: 1000
+total_images: 1281167
+save_interval: 1
+validate: True
+valid_interval: 1
+epochs: 120
+topk: 5
+image_shape: [4, 224, 224]
+
+use_dali: True
+use_gpu: True
+data_format: "NCHW"
+image_channel: &image_channel 4
+image_shape: [*image_channel, 224, 224]
+
+use_mix: False
+ls_epsilon: -1
+
+# mixed precision training
+AMP:
+    scale_loss: 128.0
+    use_dynamic_loss_scaling: True
+    use_pure_fp16: &use_pure_fp16 True
+
+LEARNING_RATE:
+    function: 'Piecewise'          
+    params:                   
+        lr: 0.1               
+        decay_epochs: [30, 60, 90] 
+        gamma: 0.1 
+
+OPTIMIZER:
+    function: 'Momentum'
+    params:
+        momentum: 0.9
+        multi_precision: *use_pure_fp16
+    regularizer:
+        function: 'L2'
+        factor: 0.000100
+
+TRAIN:
+    batch_size: 256
+    num_workers: 4
+    file_list: "./dataset/ILSVRC2012/train_list.txt"
+    data_dir: "./dataset/ILSVRC2012/"
+    shuffle_seed: 0
+    transforms:
+        - DecodeImage:
+            to_rgb: True
+            to_np: False
+            channel_first: False
+        - RandCropImage:
+            size: 224
+        - RandFlipImage:
+            flip_code: 1
+        - NormalizeImage:
+            scale: 1./255.
+            mean: [0.485, 0.456, 0.406]
+            std: [0.229, 0.224, 0.225]
+            order: ''
+            output_fp16: *use_pure_fp16
+            channel_num: *image_channel
+        - ToCHWImage:
+
+VALID:
+    batch_size: 64
+    num_workers: 4
+    file_list: "./dataset/ILSVRC2012/val_list.txt"
+    data_dir: "./dataset/ILSVRC2012/"
+    shuffle_seed: 0
+    transforms:
+        - DecodeImage:
+            to_rgb: True
+            to_np: False
+            channel_first: False
+        - ResizeImage:
+            resize_short: 256
+        - CropImage:
+            size: 224
+        - NormalizeImage:
+            scale: 1.0/255.0
+            mean: [0.485, 0.456, 0.406]
+            std: [0.229, 0.224, 0.225]
+            order: ''
+        - ToCHWImage:

ppcls/modeling/architectures/resnext.py

@@ -41,9 +41,9 @@ class ConvBNLayer(nn.Layer):
                  stride=1,
                  groups=1,
                  act=None,
-                 name=None):
+                 name=None,
+                 data_format="NCHW"):
         super(ConvBNLayer, self).__init__()
-
         self._conv = Conv2D(
             in_channels=num_channels,
             out_channels=num_filters,
@@ -52,7 +52,8 @@ class ConvBNLayer(nn.Layer):
             padding=(filter_size - 1) // 2,
             groups=groups,
             weight_attr=ParamAttr(name=name + "_weights"),
-            bias_attr=False)
+            bias_attr=False,
+            data_format=data_format)
         if name == "conv1":
             bn_name = "bn_" + name
         else:
@@ -63,7 +64,8 @@ class ConvBNLayer(nn.Layer):
             param_attr=ParamAttr(name=bn_name + '_scale'),
             bias_attr=ParamAttr(bn_name + '_offset'),
             moving_mean_name=bn_name + '_mean',
-            moving_variance_name=bn_name + '_variance')
+            moving_variance_name=bn_name + '_variance',
+            data_layout=data_format)
 
     def forward(self, inputs):
         y = self._conv(inputs)
@@ -78,15 +80,16 @@ class BottleneckBlock(nn.Layer):
                  stride,
                  cardinality,
                  shortcut=True,
-                 name=None):
+                 name=None,
+                 data_format="NCHW"):
         super(BottleneckBlock, self).__init__()
-
         self.conv0 = ConvBNLayer(
             num_channels=num_channels,
             num_filters=num_filters,
             filter_size=1,
             act='relu',
-            name=name + "_branch2a")
+            name=name + "_branch2a",
+            data_format=data_format)
         self.conv1 = ConvBNLayer(
             num_channels=num_filters,
             num_filters=num_filters,
@@ -94,13 +97,15 @@ class BottleneckBlock(nn.Layer):
             groups=cardinality,
             stride=stride,
             act='relu',
-            name=name + "_branch2b")
+            name=name + "_branch2b",
+            data_format=data_format)
         self.conv2 = ConvBNLayer(
             num_channels=num_filters,
             num_filters=num_filters * 2 if cardinality == 32 else num_filters,
             filter_size=1,
             act=None,
-            name=name + "_branch2c")
+            name=name + "_branch2c",
+            data_format=data_format)
 
         if not shortcut:
             self.short = ConvBNLayer(
@@ -109,7 +114,8 @@ class BottleneckBlock(nn.Layer):
                 if cardinality == 32 else num_filters,
                 filter_size=1,
                 stride=stride,
-                name=name + "_branch1")
+                name=name + "_branch1",
+                data_format=data_format)
 
         self.shortcut = shortcut
 
@@ -129,10 +135,12 @@ class BottleneckBlock(nn.Layer):
 
 
 class ResNeXt(nn.Layer):
-    def __init__(self, layers=50, class_dim=1000, cardinality=32):
+    def __init__(self, layers=50, class_dim=1000, cardinality=32, input_image_channel=3, data_format="NCHW"):
         super(ResNeXt, self).__init__()
 
         self.layers = layers
+        self.data_format = data_format
+        self.input_image_channel = input_image_channel
         self.cardinality = cardinality
         supported_layers = [50, 101, 152]
         assert layers in supported_layers, \
@@ -153,13 +161,14 @@ class ResNeXt(nn.Layer):
                        1024] if cardinality == 32 else [256, 512, 1024, 2048]
 
         self.conv = ConvBNLayer(
-            num_channels=3,
+            num_channels=self.input_image_channel,
             num_filters=64,
             filter_size=7,
             stride=2,
             act='relu',
-            name="res_conv1")
-        self.pool2d_max = MaxPool2D(kernel_size=3, stride=2, padding=1)
+            name="res_conv1",
+            data_format=self.data_format)
+        self.pool2d_max = MaxPool2D(kernel_size=3, stride=2, padding=1, data_format=self.data_format)
 
         self.block_list = []
         for block in range(len(depth)):
@@ -181,11 +190,12 @@ class ResNeXt(nn.Layer):
                         stride=2 if i == 0 and block != 0 else 1,
                         cardinality=self.cardinality,
                         shortcut=shortcut,
-                        name=conv_name))
+                        name=conv_name,
+                        data_format=self.data_format))
                 self.block_list.append(bottleneck_block)
                 shortcut = True
 
-        self.pool2d_avg = AdaptiveAvgPool2D(1)
+        self.pool2d_avg = AdaptiveAvgPool2D(1, data_format=self.data_format)
 
         self.pool2d_avg_channels = num_channels[-1] * 2
 
@@ -199,6 +209,10 @@ class ResNeXt(nn.Layer):
             bias_attr=ParamAttr(name="fc_offset"))
 
     def forward(self, inputs):
+        with paddle.static.amp.fp16_guard():
+            if self.data_format == "NHWC":
+                inputs = paddle.tensor.transpose(inputs, [0, 2, 3, 1])
+                inputs.stop_gradient = True
             y = self.conv(inputs)
             y = self.pool2d_max(y)
             for block in self.block_list: