Merge branch 'vision-merge' into 'main'

vision third phase merge: pretraining methods + mit,swin backbones

See merge request ADLR/megatron-lm!384

LICENSE

@@ -29,12 +29,13 @@ The following applies to all files unless otherwise noted:
 --
 
 This repository also contains code from Hugging Face Inc., Google Research,
-Facebook (from their Fairseq project), and Philip Popien. Files from these
-organizations have notices at the top of each file. Below are licenses
-used in those files, as indicated.
+Facebook (from their Fairseq and Dino projects), Microsoft(from their 
+Swin-Transformer project)and Philip Popien. Files from these 
+organizations have notices at  the top of each file. Below are 
+licenses used in those files, as indicated.
 
 
-------------- LICENSE FOR huggingface and Google Research code  --------------
+------------- LICENSE FOR Facebook, huggingface and Google Research code  --------------
 
 
                                  Apache License
@@ -263,3 +264,113 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 
+------------- LICENSE FOR Mircrosoft Swin transformer code --------------
+
+MIT License
+
+Copyright (c) Microsoft Corporation.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE
+
+
+--------------- NVIDIA Source Code License for SegFormer -----------------
+1. Definitions
+
+“Licensor” means any person or entity that distributes its Work.
+
+“Software” means the original work of authorship made available under this
+License.
+
+“Work” means the Software and any additions to or derivative works of the
+Software that are made available under this License.
+
+The terms “reproduce,” “reproduction,” “derivative works,” and 
+“distribution” have the meaning as provided under U.S. copyright law;
+provided, however, that for the purposes of this License, derivative works
+shall not include works that remain separable from, or merely link 
+(or bind by name) to the interfaces of, the Work.
+
+Works, including the Software, are “made available” under this License by 
+including in or with the Work either (a) a copyright notice referencing 
+the applicability of this License to the Work, or (b) a copy of this License.
+
+2. License Grant
+
+2.1 Copyright Grant. Subject to the terms and conditions of this License,
+each Licensor grants to you a perpetual, worldwide, non-exclusive, 
+royalty-free, copyright license to reproduce, prepare derivative works of, 
+publicly  display, publicly perform, sublicense and distribute its Work 
+and any resulting derivative works in any form.
+
+3. Limitations
+
+3.1 Redistribution. You may reproduce or distribute the Work only if 
+(a) you do so under this License, (b) you include a complete copy of this 
+License with your distribution, and (c) you retain without modification any
+copyright, patent, trademark, or attribution notices that are present
+in the Work.
+
+3.2 Derivative Works. You may specify that additional or different terms 
+apply to the use, reproduction, and distribution of your derivative works 
+of the Work (“Your Terms”) only if (a) Your Terms provide that the use
+limitation in Section 3.3 applies to your derivative works, and (b) you 
+identify the specific derivative works that are subject to Your Terms. 
+Notwithstanding Your Terms, this License (including the redistribution
+requirements in Section 3.1) will continue to apply to the Work itself.
+
+3.3 Use Limitation. The Work and any derivative works thereof only may 
+be used or intended for use non-commercially. Notwithstanding the 
+foregoing, NVIDIA and its affiliates may use the Work and any derivative
+works commercially. As used herein, “non-commercially” means for research 
+or evaluation purposes only.
+
+3.4 Patent Claims. If you bring or threaten to bring a patent claim against 
+any Licensor (including any claim, cross-claim or counterclaim in a lawsuit) 
+to enforce any patents that you allege are infringed by any Work, then
+your rights under this License from such Licensor (including the grant 
+in Section 2.1) will terminate immediately.
+
+3.5 Trademarks. This License does not grant any rights to use any Licensor’s 
+or its affiliates’ names, logos, or trademarks, except as necessary to 
+reproduce the notices described in this License.
+
+3.6 Termination. If you violate any term of this License, then your rights 
+under this License (including the grant in Section 2.1) will terminate 
+immediately.
+
+4. Disclaimer of Warranty.
+
+THE WORK IS PROVIDED “AS IS” WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 
+EITHER EXPRESS OR IMPLIED, INCLUDING WARRANTIES OR CONDITIONS OF 
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE OR NON-INFRINGEMENT.
+YOU BEAR THE RISK OF UNDERTAKING ANY ACTIVITIES UNDER THIS LICENSE.
+
+5. Limitation of Liability.
+
+EXCEPT AS PROHIBITED BY APPLICABLE LAW, IN NO EVENT AND UNDER NO LEGAL 
+THEORY, WHETHER IN TORT (INCLUDING NEGLIGENCE), CONTRACT, OR OTHERWISE 
+SHALL ANY LICENSOR BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY DIRECT,
+INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT 
+OF OR RELATED TO THIS LICENSE, THE USE OR INABILITY TO USE THE WORK 
+(INCLUDING BUT NOT LIMITED TO LOSS OF GOODWILL, BUSINESS INTERRUPTION,
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+COMMERCIAL DAMAGES OR LOSSES), EVEN IF THE LICENSOR HAS BEEN
+ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+

megatron/arguments.py

@@ -39,7 +39,7 @@ def parse_args(extra_args_provider=None, defaults={},
     parser = _add_data_args(parser)
     parser = _add_autoresume_args(parser)
     parser = _add_biencoder_args(parser)
-    parser = _add_vit_args(parser)
+    parser = _add_vision_args(parser)
     parser = _add_logging_args(parser)
     parser = _add_inference_args(parser)
 
@@ -856,9 +856,10 @@ def _add_biencoder_args(parser):
     return parser
 
 
-def _add_vit_args(parser):
-    group = parser.add_argument_group(title="vit")
+def _add_vision_args(parser):
+    group = parser.add_argument_group(title="vision")
 
+    # general vision arguements
     group.add_argument('--num-classes', type=int, default=1000,
                        help='num of classes in vision classificaiton task')
     group.add_argument('--img-h', type=int, default=224,
@@ -868,7 +869,7 @@ def _add_vit_args(parser):
     group.add_argument('--num-channels', type=int, default=3,
                        help='Number of channels in input image data')
     group.add_argument('--patch-dim', type=int, default=16,
-                       help='patch dimension used in vit')
+                       help='patch dimension')
     group.add_argument('--classes-fraction', type=float, default=1.0,
                        help='training with fraction of classes.')
     group.add_argument('--data-per-class-fraction', type=float, default=1.0,
@@ -876,5 +877,49 @@ def _add_vit_args(parser):
     group.add_argument('--no-data-sharding', action='store_false',
                        help='Disable data sharding.',
                        dest='data_sharding')
+    group.add_argument('--head-lr-mult', type=float, default=1.0,
+                       help='learning rate multiplier for head during finetuning')
+
+    # pretraining type and backbone selection`
+    group.add_argument('--vision-pretraining', action='store_true',
+                       help='flag to indicate vision pretraining')
+    group.add_argument('--vision-pretraining-type', type=str, default='classify',
+                       choices=['classify', 'inpaint', 'dino'],
+                       help='pretraining objectives')
+    group.add_argument('--vision-backbone-type', type=str, default='vit',
+                       choices=['vit', 'mit', 'swin'],
+                       help='backbone types types')
+    group.add_argument('--swin-backbone-type', type=str, default='tiny',
+                       choices=['tiny', 'base', 'h3'],
+                       help='pretraining objectives')
+    
+    # inpainting arguments
+    group.add_argument('--mask-type', type=str, default='random',
+                       choices=['random', 'row'],
+                       help='mask types')
+    group.add_argument('--mask-factor', type=float, default=1.0,
+                       help='mask size scaling parameter')
+ 
+    # dino arguments
+    group.add_argument('--iter-per-epoch', type=int, default=1250,
+                       help='iterations per epoch')
+    group.add_argument('--dino-local-img-size', type=int, default=96,
+                       help='Image size for vision classification task')
+    group.add_argument('--dino-local-crops-number', type=int, default=10,
+                       help='Number of local crops')
+    group.add_argument('--dino-head-hidden-size', type=int, default=2048,
+                       help='Hidden dimension size in dino head')
+    group.add_argument('--dino-bottleneck-size', type=int, default=256,
+                       help='Bottle neck dimension in dino head ')
+    group.add_argument('--dino-freeze-last-layer', type=float, default=1,
+                       help='Freezing last layer weights')
+    group.add_argument('--dino-norm-last-layer', action='store_true',
+                       help='Disable Norm in last layer.')
+    group.add_argument('--dino-warmup-teacher-temp', type=float, default=0.04,
+                       help='warump teacher temperature')
+    group.add_argument('--dino-teacher-temp', type=float, default=0.07,
+                       help='teacher temperature')
+    group.add_argument('--dino-warmup-teacher-temp-epochs', type=int, default=30,
+                       help='warmup teacher temperaure epochs')
 
     return parser

megatron/data/vit_dataset.py

@@ -22,6 +22,43 @@ from megatron import get_args
 from megatron.data.image_folder import ImageFolder
 from megatron.data.autoaugment import ImageNetPolicy
 from megatron.data.data_samplers import RandomSeedDataset
+from PIL import Image, ImageFilter, ImageOps
+
+
+class GaussianBlur(object):
+    """
+    Apply Gaussian Blur to the PIL image.
+    """
+    def __init__(self, p=0.5, radius_min=0.1, radius_max=2.):
+        self.prob = p
+        self.radius_min = radius_min
+        self.radius_max = radius_max
+
+    def __call__(self, img):
+        do_it = random.random() <= self.prob
+        if not do_it:
+            return img
+
+        return img.filter(
+            ImageFilter.GaussianBlur(
+                radius=random.uniform(self.radius_min, self.radius_max)
+            )
+        )
+
+
+class Solarization(object):
+    """
+    Apply Solarization to the PIL image.
+    """
+    def __init__(self, p):
+        self.p = p
+
+    def __call__(self, img):
+        if random.random() < self.p:
+            return ImageOps.solarize(img)
+        else:
+            return img
+
 
 class ClassificationTransform():
     def __init__(self, image_size, train=True):
@@ -52,14 +89,160 @@ class ClassificationTransform():
         return output
 
 
+class InpaintingTransform():
+    def __init__(self, image_size, train=True):
+
+        args = get_args()
+        self.mask_factor = args.mask_factor
+        self.mask_type = args.mask_type
+        self.image_size = image_size
+        self.patch_size = args.patch_dim
+        self.mask_size = int(self.mask_factor*(image_size[0]/self.patch_size)*(image_size[1]/self.patch_size))
+        self.train = train
+        assert args.fp16 or args.bf16
+        self.data_type = torch.half if args.fp16 else torch.bfloat16
+     
+        if self.train:
+            self.transform = T.Compose([
+                T.RandomResizedCrop(self.image_size),
+                T.RandomHorizontalFlip(),
+                T.ColorJitter(0.4, 0.4, 0.4, 0.1),
+                ImageNetPolicy(),
+                T.ToTensor(),
+                T.ConvertImageDtype(self.data_type)
+            ])
+        else:
+            self.transform = T.Compose([
+                T.Resize(self.image_size, interpolation=2),
+                T.CenterCrop(self.image_size),
+                T.ToTensor(),
+                T.ConvertImageDtype(self.data_type)
+            ])
+
+    def gen_mask(self, image_size, mask_size, mask_type, patch_size):
+        # output: mask as a list with indices for missing patches
+        action_list = [[0, 1], [0, -1], [1, 0], [-1, 0]]
+        assert image_size[0] == image_size[1]
+        img_size_patch = image_size[0] // patch_size
+
+        # drop masked patches
+        mask = torch.zeros((image_size[0], image_size[1]), dtype=torch.float)
+
+        if mask_type == 'random':
+            x = torch.randint(0, img_size_patch, ())
+            y = torch.randint(0, img_size_patch, ())
+            for i in range(mask_size):
+                r = torch.randint(0, len(action_list), ())
+                x = torch.clamp(x + action_list[r][0], min=0, max=img_size_patch - 1)
+                y = torch.clamp(y + action_list[r][1], min=0, max=img_size_patch - 1)
+                x_offset = x * patch_size
+                y_offset = y * patch_size
+                mask[x_offset:x_offset+patch_size, y_offset:y_offset+patch_size] = 1
+        else:
+            assert mask_type == 'row'
+            count = 0
+            for x in reversed(range(img_size_patch)):
+                for y in reversed(range(img_size_patch)):
+                    if (count < mask_size):
+                        count += 1
+                        x_offset = x * patch_size
+                        y_offset = y * patch_size
+                        mask[x_offset:x_offset+patch_size, y_offset:y_offset+patch_size] = 1
+        return mask
+
+    def __call__(self, input):
+        trans_input = self.transform(input)
+        mask = self.gen_mask(self.image_size, self.mask_size, 
+			     self.mask_type, self.patch_size)
+        mask = mask.unsqueeze(dim=0)
+        return trans_input, mask
+
+
+class DinoTransform(object):
+    def __init__(self, image_size, train=True):
+        args = get_args()
+        self.data_type = torch.half if args.fp16 else torch.bfloat16
+
+        flip_and_color_jitter = T.Compose([
+            T.RandomHorizontalFlip(p=0.5),
+            T.RandomApply(
+                [T.ColorJitter(brightness=0.4, contrast=0.4,
+			       saturation=0.2, hue=0.1)],
+                p=0.8
+            ),
+            T.RandomGrayscale(p=0.2),
+        ])
+
+        if args.fp16 or args.bf16:
+            normalize = T.Compose([
+                T.ToTensor(),
+                T.Normalize((0.485, 0.456, 0.406), (0.229, 0.224, 0.225)),
+                T.ConvertImageDtype(self.data_type)
+            ])
+        else:
+            normalize = T.Compose([
+                T.ToTensor(),
+                T.Normalize((0.485, 0.456, 0.406), (0.229, 0.224, 0.225)),
+            ])
+
+        # first global crop
+        scale_const = 0.4
+        self.global_transform1 = T.Compose([
+            T.RandomResizedCrop(image_size,
+                                scale=(scale_const, 1),
+                                interpolation=Image.BICUBIC),
+            flip_and_color_jitter,
+            GaussianBlur(1.0),
+            normalize
+        ])
+        # second global crop
+        self.global_transform2 = T.Compose([
+            T.RandomResizedCrop(image_size,
+                                scale=(scale_const, 1),
+                                interpolation=Image.BICUBIC),
+            flip_and_color_jitter,
+            GaussianBlur(0.1),
+            Solarization(0.2),
+            normalize
+        ])
+        # transformation for the local small crops
+        self.local_crops_number = args.dino_local_crops_number
+        self.local_transform = T.Compose([
+            T.RandomResizedCrop(args.dino_local_img_size,
+                                scale=(0.05, scale_const),
+                                interpolation=Image.BICUBIC),
+            flip_and_color_jitter,
+            GaussianBlur(p=0.5),
+            normalize
+        ])
+
+    def __call__(self, image):
+        crops = []
+        crops.append(self.global_transform1(image))
+        crops.append(self.global_transform2(image))
+        for _ in range(self.local_crops_number):
+            crops.append(self.local_transform(image))
+        return crops
+
 
 def build_train_valid_datasets(data_path, image_size=224):
     args = get_args()
-    train_transform = ClassificationTransform(image_size)
-    val_transform = ClassificationTransform(image_size, train=False)
+
+    if args.vision_pretraining_type == 'classify':
+        train_transform = ClassificationTransform(image_size)
+        val_transform = ClassificationTransform(image_size, train=False)
+    elif args.vision_pretraining_type == 'inpaint':
+        train_transform = InpaintingTransform(image_size, train=False)
+        val_transform = InpaintingTransform(image_size, train=False)
+    elif args.vision_pretraining_type == 'dino':
+        train_transform = DinoTransform(image_size, train=True)
+        val_transform = ClassificationTransform(image_size, train=False)
+    else:
+        raise Exception('{} vit pretraining type is not supported.'.format(
+                args.vit_pretraining_type))
 
     # training dataset
-    train_data_path = data_path[0]
+    train_data_path = data_path[0] if len(data_path) <= 2 else data_path[2]
     train_data = ImageFolder(
         root=train_data_path,
         transform=train_transform,

megatron/model/vision/classification.py

@@ -16,9 +16,11 @@
 """Vision Transformer(VIT) model."""
 
 import torch
+from torch.nn.init import trunc_normal_
 from megatron import get_args
 from megatron.model.utils import get_linear_layer
 from megatron.model.vision.vit_backbone import VitBackbone, VitMlpHead
+from megatron.model.vision.mit_backbone import mit_b3_avg
 from megatron.model.module import MegatronModule
 
 class VitClassificationModel(MegatronModule):
@@ -61,3 +63,35 @@ class VitClassificationModel(MegatronModule):
             hidden_states = self.head(hidden_states)
 
         return hidden_states
+
+
+class MitClassificationModel(MegatronModule):
+    """Mix vision Transformer Model."""
+
+    def __init__(self, num_classes,
+                 pre_process=True, post_process=True):
+        super(MitClassificationModel, self).__init__()
+        args = get_args()
+
+        self.hidden_size = args.hidden_size
+        self.num_classes = num_classes
+
+        self.backbone = mit_b3_avg()
+        self.head = torch.nn.Linear(512, num_classes)
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, torch.nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, torch.nn.Linear) and m.bias is not None:
+                torch.nn.init.constant_(m.bias, 0)
+
+    def set_input_tensor(self, input_tensor):
+        """See megatron.model.transformer.set_input_tensor()"""
+        pass
+
+    def forward(self, input):
+        hidden_states = self.backbone(input)
+        hidden_states = self.head(hidden_states)
+
+        return hidden_states

megatron/model/vision/dino.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the Apache license found in the
+# LICENSE file in the root directory of this source tree.
+
+# copied from https://github.com/facebookresearch/dino/blob/main/main_dino.py
+# reworked/refactored some parts to make it run in Megatron.
+import math
+import apex
+import einops
+import torch
+import numpy as np
+import torch.nn.functional as F
+from torch.nn.init import trunc_normal_
+from megatron import get_args, print_rank_0
+from megatron.model.utils import get_linear_layer
+from megatron.model.vision.vit_backbone import VitBackbone
+from megatron.model.module import MegatronModule
+from megatron.model.vision.mit_backbone import mit_b5_avg
+from megatron.model.vision.esvit_swin_backbone import get_swin
+
+
+class DINOLoss(torch.nn.Module):
+    def __init__(self, out_dim, ncrops, warmup_teacher_temp, teacher_temp,
+                 warmup_teacher_temp_epochs, nepochs, student_temp=0.1,
+                 center_momentum=0.9):
+        super().__init__()
+        self.student_temp = student_temp
+        self.center_momentum = center_momentum
+        self.ncrops = ncrops
+        self.register_buffer("center", torch.zeros(1, out_dim))
+        # we apply a warm up for the teacher temperature because
+        # a too high temperature makes the training instable at the beginning
+        self.teacher_temp_schedule = np.concatenate((
+            np.linspace(warmup_teacher_temp,
+                        teacher_temp, warmup_teacher_temp_epochs),
+            np.ones(nepochs - warmup_teacher_temp_epochs) * teacher_temp
+        ))
+        self.teacher_temp = teacher_temp
+
+    def forward(self, student_output, teacher_output, iteration):
+        """
+        Cross-entropy between softmax outputs of the teacher
+        and student network.
+        """
+        args = get_args()
+        student_out = student_output / self.student_temp
+        student_out = student_out.chunk(self.ncrops)
+
+        epoch = iteration // args.iter_per_epoch
+
+        # teacher centering and sharpening
+        temp = self.teacher_temp_schedule[epoch]
+        teacher_out = F.softmax((teacher_output - self.center) / temp, dim=-1)
+
+        teacher_out = teacher_out.detach().chunk(2)
+
+        total_loss = 0
+        n_loss_terms = 0
+        for iq, q in enumerate(teacher_out):
+            for v in range(len(student_out)):
+                if v == iq:
+                    # we skip cases where student and teacher operate on the same view
+                    continue
+                loss = torch.sum(-q * F.log_softmax(student_out[v], dim=-1), dim=-1)
+                total_loss += loss.mean()
+                n_loss_terms += 1
+        total_loss /= n_loss_terms
+        self.update_center(teacher_output)
+        return total_loss
+
+    @torch.no_grad()
+    def update_center(self, teacher_output):
+        """
+        Update center used for teacher output.
+        """
+        batch_center = torch.sum(teacher_output, dim=0, keepdim=True)
+        torch.distributed.all_reduce(batch_center)
+        batch_center = batch_center / (len(teacher_output) * torch.distributed.get_world_size())
+        self.center = self.center * self.center_momentum + batch_center * (1 - self.center_momentum)
+
+class DINOHead(torch.nn.Module):
+    def __init__(self, in_dim, out_dim, norm_last_layer=True, nlayers=3):
+        super().__init__()
+        args = get_args()
+        hidden_dim = args.dino_head_hidden_size
+        bottleneck_dim = args.dino_bottleneck_size
+        nlayers = max(nlayers, 1)
+        if nlayers == 1:
+            self.mlp = torch.nn.Linear(in_dim, bottleneck_dim)
+        else:
+            layers = [torch.nn.Linear(in_dim, hidden_dim)]
+            layers.append(torch.nn.GELU())
+            for _ in range(nlayers - 2):
+                layers.append(torch.nn.Linear(hidden_dim, hidden_dim))
+                layers.append(torch.nn.GELU())
+            layers.append(torch.nn.Linear(hidden_dim, bottleneck_dim))
+            self.mlp = torch.nn.Sequential(*layers)
+        self.apply(self._init_weights)
+        self.last_layer = torch.nn.utils.weight_norm(torch.nn.Linear(bottleneck_dim, out_dim, bias=False))
+        self.last_layer.weight_g.data.fill_(1)
+        if norm_last_layer:
+            self.last_layer.weight_g.requires_grad = False
+
+    def _init_weights(self, m):
+        if isinstance(m, torch.nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, torch.nn.Linear) and m.bias is not None:
+                torch.nn.init.constant_(m.bias, 0)
+
+    def forward(self, x):
+        x = self.mlp(x)
+        x = torch.nn.functional.normalize(x, dim=-1, p=2)
+        x = self.last_layer(x)
+        return x
+
+
+class MultiCropWrapper(MegatronModule):
+
+    """
+    Perform forward pass separately on each resolution input.
+    The inputs corresponding to a single resolution are clubbed and single
+    forward is run on the same resolution inputs. Hence we do several
+    forward passes = number of different resolutions used. We then
+    concatenate all the output features and run the head forward on these
+    concatenated features.
+    """
+    def __init__(self, backbone, head):
+        super(MultiCropWrapper, self).__init__()
+        # disable layers dedicated to ImageNet labels classification
+        #backbone.fc, backbone.head = torch.nn.Identity(), torch.nn.Identity()
+        self.backbone = backbone
+        self.head = head
+
+    def forward(self, x):
+        # convert to list
+        if not isinstance(x, list):
+            x = [x]
+        idx_crops = torch.cumsum(torch.unique_consecutive(
+            torch.tensor([inp.shape[-1] for inp in x]),
+            return_counts=True,
+        )[1], 0)
+
+        start_idx = 0
+        for end_idx in idx_crops:
+            _out = self.backbone(torch.cat(x[start_idx: end_idx]))
+            if start_idx == 0:
+                output = _out
+            else:
+                output = torch.cat((output, _out))
+            start_idx = end_idx
+        # Run the head forward on the concatenated features.
+        if self.training:
+            return self.head(output)
+        else:
+            return output
+
+
+def cosine_scheduler(base_value, final_value, epochs, niter_per_ep,
+                     warmup_epochs=0, start_warmup_value=0):
+    warmup_schedule = np.array([])
+    warmup_iters = warmup_epochs * niter_per_ep
+    if warmup_epochs > 0:
+        warmup_schedule = \
+                np.linspace(start_warmup_value, base_value, warmup_iters)
+
+    iters = np.arange(epochs * niter_per_ep - warmup_iters)
+    schedule = final_value + 0.5 * (base_value - final_value) \
+        * (1 + np.cos(np.pi * iters / len(iters)))
+
+    schedule = np.concatenate((warmup_schedule, schedule))
+    assert len(schedule) == epochs * niter_per_ep
+    return schedule
+
+
+def get_student_backbone_and_num_features(pre_process=True, post_process=True):
+    args = get_args()
+
+    if args.vision_backbone_type == 'vit':
+        student = VitBackbone(pre_process=pre_process,
+                              post_process=post_process,
+                              drop_path_rate=0.1,
+                              single_token_output=True)
+        num_features = args.hidden_size
+    elif args.vision_backbone_type == 'mit':
+        student = mit_b5_avg(drop_path_rate=0.1)
+        num_features = 512
+    elif args.vision_backbone_type == 'swin':
+        student = get_swin()
+        num_features = student.num_features
+    else:
+        raise Exception('{} vision backbone is not supported.'.format(
+                              args.vision_backbone_type))
+ 
+    return student, num_features
+
+def get_teacher_backbone_and_num_features(pre_process=True, post_process=True):
+    args = get_args()
+
+    if args.vision_backbone_type == 'vit':
+        teacher = VitBackbone(pre_process=pre_process,
+                              post_process=post_process,
+                              single_token_output=True)
+        num_features = args.hidden_size
+    elif args.vision_backbone_type == 'mit':
+        teacher = mit_b5_avg(drop_path_rate=0.0)
+        num_features = 512
+    elif args.vision_backbone_type == 'swin':
+        teacher = get_swin(is_teacher=True)
+        num_features = teacher.num_features
+    else:
+        raise Exception('{} vision backbone is not supported.'.format(
+                              args.vision_backbone_type))
+    return teacher, num_features
+
+
+class DINOPretrainModel(MegatronModule):
+    def __init__(self, pre_process=True, post_process=True):
+        super(DINOPretrainModel, self).__init__()
+        args = get_args()
+        self.out_dim = 65536
+
+        self.dino_loss = DINOLoss(
+            self.out_dim,
+            args.dino_local_crops_number + 2,
+            args.dino_warmup_teacher_temp,
+            args.dino_teacher_temp,
+            args.dino_warmup_teacher_temp_epochs,
+            300,
+        )
+
+        self.pre_process = pre_process
+        self.post_process = post_process
+        self.momentum_teacher = 0.996
+
+        student_backbone, num_features = \
+            get_student_backbone_and_num_features(pre_process, post_process)
+
+        self.student = MultiCropWrapper(
+            student_backbone,
+            DINOHead(num_features, self.out_dim,
+                     norm_last_layer=args.dino_norm_last_layer)
+        )
+
+        self.momentum_schedule = cosine_scheduler(
+            self.momentum_teacher, 1,
+            args.train_iters // args.iter_per_epoch,
+            args.iter_per_epoch
+        )
+
+        teacher_backbone, num_features = \
+            get_teacher_backbone_and_num_features(pre_process, post_process)
+        self.teacher = MultiCropWrapper(
+            teacher_backbone,
+            DINOHead(num_features, self.out_dim)
+        )
+        self.teacher.load_state_dict(self.student.state_dict())
+
+        for p in self.teacher.parameters():
+            if hasattr(p, "requires_grad") and p.requires_grad is not None:
+                p.requires_grad = False
+
+    def set_input_tensor(self, tensor):
+        pass
+
+    def forward(self, input):
+        student_output = None
+        if self.training:
+            student_output = self.student(input)
+            teacher_output = self.teacher(input[:2])
+        else:
+            teacher_output = self.teacher(input)
+        return student_output, teacher_output
+
+    def cancel_gradients_last_layer(self, iteration):
+        args = get_args()
+        epoch = iteration // args.iter_per_epoch
+        if epoch < args.dino_freeze_last_layer:
+            for n, p in self.student.named_parameters():
+                if "last_layer" in n:
+                    p.grad = None
+
+    def update_momentum(self, iteration):
+        with torch.no_grad():
+            m = self.momentum_schedule[iteration]
+            for param_q, param_k in zip(self.student.parameters(), self.teacher.parameters()):
+                param_k.data.mul_(m).add_((1 - m) * param_q.detach().data)
+

megatron/model/vision/inpainting.py

+# coding=utf-8
+# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
+#
+# This source code is licensed under the BSD license found in the
+# LICENSE file in the root directory of this source tree.
+i
+import math
+import apex
+import einops
+import torch
+import torch.nn.functional as F
+from megatron import get_args, print_rank_0
+from megatron.model.utils import get_linear_layer
+from megatron.model.vision.vit_backbone import VitBackbone
+from megatron.model.module import MegatronModule
+from megatron.model.vision.mit_backbone import mit_b3
+from megatron.model.vision.utils import resize_
+
+
+class VitInpaintingModel(MegatronModule):
+
+    def __init__(self, pre_process=True, post_process=True):
+        super(VitInpaintingModel, self).__init__()
+        args = get_args()
+
+        self.pre_process = pre_process
+        self.post_process = post_process
+        self.hidden_size = args.hidden_size
+        self.backbone = VitBackbone(
+            pre_process=self.pre_process,
+            post_process=self.post_process,
+            class_token=False,
+        )
+        self.patch_dim = args.patch_dim
+        self.img_h = args.img_h
+        self.img_w = args.img_w
+        self.seq_length = args.seq_length
+        # full mask
+
+        if self.post_process:
+            self.linear_decoder = get_linear_layer(
+                self.hidden_size,
+                self.backbone.flatten_dim,
+                torch.nn.init.zeros_
+            )
+
+    def set_input_tensor(self, input_tensor):
+        self.backbone.set_input_tensor(input_tensor)
+
+    def forward(self, input):
+
+        hidden_states = self.backbone(input)
+
+        if not self.post_process:
+            return hidden_states
+        decoded_output = self.linear_decoder(hidden_states)
+        output = einops.rearrange(
+                decoded_output,
+                "b (h w) (p1 p2 c) -> b c (h p1) (w p2)",
+                p1=self.patch_dim,
+                p2=self.patch_dim,
+                h=self.img_h//self.patch_dim,
+                w=self.img_w//self.patch_dim,
+            )
+
+        return output
+
+
+class MLP(torch.nn.Module):
+    """
+    Linear Embedding
+    """
+    def __init__(self, input_dim=2048, embed_dim=768):
+        super().__init__()
+        self.proj = torch.nn.Linear(input_dim, embed_dim)
+
+    def forward(self, x):
+        x = x.flatten(2).transpose(1, 2)
+        x = self.proj(x)
+        return x
+
+
+class MitInpaintingModel(MegatronModule):
+    """Mix vision Transformer Model."""
+
+    def __init__(self, pre_process=True, post_process=True):
+        super(MitInpaintingModel, self).__init__()
+        self.pre_process = pre_process
+        self.post_process = post_process
+
+        args = get_args()
+        self.patch_dim = args.patch_dim
+        self.img_h = args.img_h
+        self.img_w = args.img_w
+        self.flatten_dim = self.patch_dim * self.patch_dim * 3
+        self.backbone = mit_b3()
+
+        self.in_channels = [64, 128, 320, 512]
+        self.embedding_dim = 768
+
+        c1_in_channels, c2_in_channels, c3_in_channels, c4_in_channels = self.in_channels
+
+        self.linear_c4 = MLP(input_dim=c4_in_channels, embed_dim=self.embedding_dim)
+        self.linear_c3 = MLP(input_dim=c3_in_channels, embed_dim=self.embedding_dim)
+        self.linear_c2 = MLP(input_dim=c2_in_channels, embed_dim=self.embedding_dim)
+        self.linear_c1 = MLP(input_dim=c1_in_channels, embed_dim=self.embedding_dim)
+
+        self.conv_fuse = torch.nn.Conv2d(self.embedding_dim*4, self.embedding_dim, 1, 1, bias=False)
+        self.norm = apex.parallel.SyncBatchNorm(self.embedding_dim)
+        self.dropout = torch.nn.Dropout2d(0.1)
+        
+        self.linear_pred = torch.nn.Conv2d(self.embedding_dim, self.flatten_dim, kernel_size=1)
+    
+    def set_input_tensor(self, input_tensor):
+        """See megatron.model.transformer.set_input_tensor()"""
+        pass
+
+    def forward(self, input):
+        c1, c2, c3, c4 = self.backbone(input)
+
+        n, _, h, w = c4.shape
+        _c4 = self.linear_c4(c4).permute(0, 2, 1).reshape(n, -1, c4.shape[2], c4.shape[3])
+        _c4 = resize(_c4, size=c1.size()[2:], mode='bilinear', align_corners=False)
+    
+        _c3 = self.linear_c3(c3).permute(0, 2, 1).reshape(n, -1, c3.shape[2], c3.shape[3])
+        _c3 = resize(_c3, size=c1.size()[2:], mode='bilinear', align_corners=False)
+
+        _c2 = self.linear_c2(c2).permute(0, 2, 1).reshape(n, -1, c2.shape[2], c2.shape[3])
+        _c2 = resize(_c2, size=c1.size()[2:], mode='bilinear', align_corners=False)
+
+        _c1 = self.linear_c1(c1).permute(0, 2, 1).reshape(n, -1, c1.shape[2], c1.shape[3])
+
+        _c = torch.cat([_c4, _c3, _c2, _c1], dim=1)
+        _c = self.conv_fuse(_c)
+ 
+        x = self.norm(_c)
+        x = F.relu(x, inplace=True)
+        x = self.dropout(x)
+
+        x = self.linear_pred(x)
+
+        output = einops.rearrange(
+            x,
+            "b (c p1 p2) h w -> b c (h p1) (w p2)",
+            p1=self.patch_dim,
+            p2=self.patch_dim,
+            h=self.img_h//self.patch_dim,
+            w=self.img_w//self.patch_dim,
+        )
+
+        return output

megatron/model/vision/knn_monitor.py

+import torch.nn.functional as F
+import torch
+from megatron import print_rank_0, get_args, mpu
+from megatron.data.vit_dataset import ClassificationTransform
+from megatron.data.image_folder import ImageFolder
+
+_FEATURE_BANK = None
+
+
+def build_data_loader(dataset, drop_last=True, shuffle=False):
+    """Data loader. Note that batch-size is the local (per GPU) batch-size."""
+    # Sampler.
+    args = get_args()
+    micro_batch_size = 16
+    num_workers = args.num_workers
+    world_size = mpu.get_data_parallel_world_size()
+    rank = mpu.get_data_parallel_rank()
+    sampler = torch.utils.data.distributed.DistributedSampler(
+        dataset, num_replicas=world_size, rank=rank,
+        drop_last=drop_last, shuffle=shuffle
+    )
+
+    # Data loader. Note that batch size is the per GPU batch size.
+    data_loader = torch.utils.data.DataLoader(
+        dataset,
+        batch_size=micro_batch_size,
+        sampler=sampler,
+        shuffle=False,
+        num_workers=num_workers,
+        drop_last=not drop_last,
+        pin_memory=True,
+    )
+    return data_loader
+
+
+def compute_feature_bank(model):
+    args = get_args()
+    global _FEATURE_BANK
+    feature_bank = []
+    feature_label = []
+
+    train_ds = ImageFolder(
+        root=args.data_path[0],
+        transform=ClassificationTransform((args.img_h, args.img_w), train=False),
+        data_per_class_fraction=1.0
+    )
+    classes = len(train_ds.classes)
+    dataloader = build_data_loader(train_ds)
+     
+    for m in model:
+        m.eval()
+
+    with torch.no_grad():
+        for i, batch in enumerate(dataloader):
+            images = batch[0].cuda().contiguous()
+            labels = batch[1].cuda().contiguous()
+            student_feature, teacher_feature = model[0](images)
+            feature = F.normalize(teacher_feature.float(), dim=1)
+            feature_bank.append(feature)
+            feature_label.append(labels)
+    
+    for m in model:
+        m.train()
+
+    # [N', D]
+    feature_bank = torch.cat(feature_bank, dim=0).contiguous()
+    feature_label = torch.cat(feature_label, dim=0).contiguous()
+
+    feature_banks = [torch.zeros_like(feature_bank)
+                     for i in range(mpu.get_data_parallel_world_size())]
+    torch.distributed.all_gather(feature_banks,
+                                 feature_bank,
+                                 group=mpu.get_data_parallel_group())
+
+    assert torch.all(torch.eq(feature_banks[mpu.get_data_parallel_rank()],
+                              feature_bank))
+
+    feature_labels = [torch.zeros_like(feature_label)
+                      for i in range(mpu.get_data_parallel_world_size())]
+    torch.distributed.all_gather(feature_labels,
+                                 feature_label,
+                                 group=mpu.get_data_parallel_group())
+
+    # [D, N]
+    feature_banks = torch.cat(feature_banks, dim=0).t().contiguous()
+    # [N]
+    feature_labels = torch.cat(feature_labels, dim=0).contiguous()
+    print_rank_0("feature_banks size is {}".format(feature_banks.size()))
+    print_rank_0("feature labels size is {}".format(feature_labels.size()))
+
+    _FEATURE_BANK = (feature_banks, feature_labels, classes)
+
+
+def get_feature_bank():
+    global _FEATURE_BANK
+    assert _FEATURE_BANK is not None
+    return _FEATURE_BANK
+
+
+# knn monitor as in InstDisc https://arxiv.org/abs/1805.01978
+# implementation follows http://github.com/zhirongw/lemniscate.pytorch and
+# https://github.com/leftthomas/SimCLR
+def knn_predict(feature, feature_bank, feature_labels, classes, knn_k, knn_t):
+    # compute cos similarity between each feature vector and feature bank ---> [B, N]
+    sim_matrix = torch.mm(feature, feature_bank)
+    # [B, K]
+    sim_weight, sim_indices = sim_matrix.topk(k=knn_k, dim=-1)
+    # [B, K]
+    sim_labels = torch.gather(feature_labels.expand(feature.size(0), -1),
+                              dim=-1,
+                              index=sim_indices)
+    sim_weight = (sim_weight / knn_t).exp()
+
+    # counts for each class
+    one_hot_label = torch.zeros(feature.size(0) * knn_k,
+                                classes,
+                                device=sim_labels.device)
+    # [B*K, C]
+    one_hot_label = one_hot_label.scatter(dim=-1,
+                                          index=sim_labels.view(-1, 1),
+                                          value=1.0)
+    # weighted score ---> [B, C]
+    pred_scores = torch.sum(
+            one_hot_label.view(feature.size(0), -1, classes) * sim_weight.unsqueeze(dim=-1),
+            dim=1)
+
+    pred_labels = pred_scores.argsort(dim=-1, descending=True)
+    return pred_labels

megatron/model/vision/mit_backbone.py

+# ---------------------------------------------------------------
+# Copyright (c) 2021, NVIDIA Corporation. All rights reserved.
+#
+# This work is licensed under the NVIDIA Source Code License
+# found in the LICENSE file in the root directory of this 
+# source tree.
+# ---------------------------------------------------------------
+import math
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from functools import partial
+from torch.nn.init import trunc_normal_
+from megatron.model.transformer import DropPath
+from megatron.model import LayerNorm
+
+
+class Mlp(nn.Module):
+    def __init__(self,
+                 in_features,
+                 hidden_features=None,
+                 out_features=None,
+                 act_layer=nn.GELU,
+                 drop=0.):
+        super().__init__()
+        out_features = out_features or in_features
+        hidden_features = hidden_features or in_features
+        self.fc1 = nn.Linear(in_features, hidden_features)
+        self.dwconv = DWConv(hidden_features)
+        self.act = act_layer()
+        self.fc2 = nn.Linear(hidden_features, out_features)
+        self.drop = nn.Dropout(drop)
+
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
+            fan_out //= m.groups
+            m.weight.data.normal_(0, math.sqrt(2.0 / fan_out))
+            if m.bias is not None:
+                m.bias.data.zero_()
+
+    def forward(self, x, H, W):
+        x = self.fc1(x)
+        x = self.dwconv(x, H, W)
+        x = self.act(x)
+        x = self.drop(x)
+        x = self.fc2(x)
+        x = self.drop(x)
+        return x
+
+
+class Attention(nn.Module):
+    def __init__(self,
+                 dim,
+                 num_heads=8,
+                 qkv_bias=False,
+                 qk_scale=None,
+                 attn_drop=0.,
+                 proj_drop=0.,
+                 sr_ratio=1):
+        super().__init__()
+        assert dim % num_heads == 0, f"dim {dim} should be divided by num_heads {num_heads}."
+
+        self.dim = dim
+        self.num_heads = num_heads
+        head_dim = dim // num_heads
+        self.scale = qk_scale or head_dim ** -0.5
+
+        self.q = nn.Linear(dim, dim, bias=qkv_bias)
+        self.kv = nn.Linear(dim, dim * 2, bias=qkv_bias)
+        self.attn_drop = nn.Dropout(attn_drop)
+        self.proj = nn.Linear(dim, dim)
+        self.proj_drop = nn.Dropout(proj_drop)
+
+        self.sr_ratio = sr_ratio
+        if sr_ratio > 1:
+            self.sr = nn.Conv2d(dim, dim, kernel_size=sr_ratio, stride=sr_ratio)
+            self.norm = LayerNorm(dim)
+
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
+            fan_out //= m.groups
+            m.weight.data.normal_(0, math.sqrt(2.0 / fan_out))
+            if m.bias is not None:
+                m.bias.data.zero_()
+
+    def forward(self, x, H, W):
+        B, N, C = x.shape
+        q = self.q(x).reshape(B, N, self.num_heads, C // self.num_heads).permute(0, 2, 1, 3)
+
+        if self.sr_ratio > 1:
+            x_ = x.permute(0, 2, 1).reshape(B, C, H, W)
+            x_ = self.sr(x_).reshape(B, C, -1).permute(0, 2, 1)
+            x_ = self.norm(x_)
+            kv = self.kv(x_).reshape(B, -1, 2, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
+        else:
+            kv = self.kv(x).reshape(B, -1, 2, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
+        k, v = kv[0], kv[1]
+
+        attn = (q @ k.transpose(-2, -1)) * self.scale
+        attn = attn.softmax(dim=-1)
+        attn = self.attn_drop(attn)
+
+        x = (attn @ v).transpose(1, 2).reshape(B, N, C)
+        x = self.proj(x)
+        x = self.proj_drop(x)
+
+        return x
+
+
+class Block(nn.Module):
+
+    def __init__(self, dim, num_heads, mlp_ratio=4., qkv_bias=False, qk_scale=None, drop=0., attn_drop=0.,
+                 drop_path=0., act_layer=nn.GELU, norm_layer=LayerNorm, sr_ratio=1):
+        super().__init__()
+        self.norm1 = norm_layer(dim)
+        self.attn = Attention(
+            dim,
+            num_heads=num_heads, qkv_bias=qkv_bias, qk_scale=qk_scale,
+            attn_drop=attn_drop, proj_drop=drop, sr_ratio=sr_ratio)
+        # NOTE: drop path for stochastic depth, we shall see if this is better than dropout here
+        self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
+        self.norm2 = norm_layer(dim)
+        mlp_hidden_dim = int(dim * mlp_ratio)
+        self.mlp = Mlp(in_features=dim, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop)
+
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
+            fan_out //= m.groups
+            m.weight.data.normal_(0, math.sqrt(2.0 / fan_out))
+            if m.bias is not None:
+                m.bias.data.zero_()
+
+    def forward(self, x, H, W):
+        x = x + self.drop_path(self.attn(self.norm1(x), H, W))
+        x = x + self.drop_path(self.mlp(self.norm2(x), H, W))
+
+        return x
+
+
+class OverlapPatchEmbed(nn.Module):
+    """ Image to Patch Embedding
+    """
+
+    def __init__(self, img_size=224, patch_size=7, stride=4, in_chans=3, embed_dim=768):
+        super().__init__()
+        img_size = (img_size, img_size)
+        patch_size = (patch_size, patch_size)
+
+        self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=stride,
+                              padding=(patch_size[0] // 2, patch_size[1] // 2))
+        self.norm = LayerNorm(embed_dim)
+
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
+            fan_out //= m.groups
+            m.weight.data.normal_(0, math.sqrt(2.0 / fan_out))
+            if m.bias is not None:
+                m.bias.data.zero_()
+
+    def forward(self, x):
+        x = self.proj(x)
+        _, _, H, W = x.shape
+        x = x.flatten(2).transpose(1, 2)
+        x = self.norm(x)
+
+        return x, H, W
+
+
+class MixVisionTransformer(nn.Module):
+    def __init__(self, img_size=224, patch_size=16, in_chans=3, num_classes=1000, embed_dims=[64, 128, 256, 512],
+                 num_heads=[1, 2, 4, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=False, qk_scale=None, drop_rate=0.,
+                 attn_drop_rate=0., drop_path_rate=0., norm_layer=LayerNorm,
+                 depths=[3, 4, 6, 3], sr_ratios=[8, 4, 2, 1], output_avg=False):
+        super().__init__()
+        self.num_classes = num_classes
+        self.depths = depths
+        self.output_avg = output_avg
+
+        # patch_embed
+        self.patch_embed1 = OverlapPatchEmbed(img_size=img_size, patch_size=7, stride=4, in_chans=in_chans,
+                                              embed_dim=embed_dims[0])
+        self.patch_embed2 = OverlapPatchEmbed(img_size=img_size // 4, patch_size=3, stride=2, in_chans=embed_dims[0],
+                                              embed_dim=embed_dims[1])
+        self.patch_embed3 = OverlapPatchEmbed(img_size=img_size // 8, patch_size=3, stride=2, in_chans=embed_dims[1],
+                                              embed_dim=embed_dims[2])
+        self.patch_embed4 = OverlapPatchEmbed(img_size=img_size // 16, patch_size=3, stride=2, in_chans=embed_dims[2],
+                                              embed_dim=embed_dims[3])
+
+        # transformer encoder
+        dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))]  # stochastic depth decay rule
+        cur = 0
+        self.block1 = nn.ModuleList([Block(
+            dim=embed_dims[0], num_heads=num_heads[0], mlp_ratio=mlp_ratios[0], qkv_bias=qkv_bias, qk_scale=qk_scale,
+            drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer,
+            sr_ratio=sr_ratios[0])
+            for i in range(depths[0])])
+        self.norm1 = norm_layer(embed_dims[0])
+
+        cur += depths[0]
+        self.block2 = nn.ModuleList([Block(
+            dim=embed_dims[1], num_heads=num_heads[1], mlp_ratio=mlp_ratios[1], qkv_bias=qkv_bias, qk_scale=qk_scale,
+            drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer,
+            sr_ratio=sr_ratios[1])
+            for i in range(depths[1])])
+        self.norm2 = norm_layer(embed_dims[1])
+
+        cur += depths[1]
+        self.block3 = nn.ModuleList([Block(
+            dim=embed_dims[2], num_heads=num_heads[2], mlp_ratio=mlp_ratios[2], qkv_bias=qkv_bias, qk_scale=qk_scale,
+            drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer,
+            sr_ratio=sr_ratios[2])
+            for i in range(depths[2])])
+        self.norm3 = norm_layer(embed_dims[2])
+
+        cur += depths[2]
+        self.block4 = nn.ModuleList([Block(
+            dim=embed_dims[3], num_heads=num_heads[3], mlp_ratio=mlp_ratios[3], qkv_bias=qkv_bias, qk_scale=qk_scale,
+            drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer,
+            sr_ratio=sr_ratios[3])
+            for i in range(depths[3])])
+        self.norm4 = norm_layer(embed_dims[3])
+
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            trunc_normal_(m.weight, std=.02)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
+            fan_out //= m.groups
+            m.weight.data.normal_(0, math.sqrt(2.0 / fan_out))
+            if m.bias is not None:
+                m.bias.data.zero_()
+
+    def reset_drop_path(self, drop_path_rate):
+        dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(self.depths))]
+        cur = 0
+        for i in range(self.depths[0]):
+            self.block1[i].drop_path.drop_prob = dpr[cur + i]
+
+        cur += self.depths[0]
+        for i in range(self.depths[1]):
+            self.block2[i].drop_path.drop_prob = dpr[cur + i]
+
+        cur += self.depths[1]
+        for i in range(self.depths[2]):
+            self.block3[i].drop_path.drop_prob = dpr[cur + i]
+
+        cur += self.depths[2]
+        for i in range(self.depths[3]):
+            self.block4[i].drop_path.drop_prob = dpr[cur + i]
+
+    def freeze_patch_emb(self):
+        self.patch_embed1.requires_grad = False
+
+    def forward_features(self, x):
+        B = x.shape[0]
+        outs = []
+
+        # stage 1
+        x, H, W = self.patch_embed1(x)
+        for i, blk in enumerate(self.block1):
+            x = blk(x, H, W)
+        x = self.norm1(x)
+        x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous()
+        outs.append(x)
+
+        # stage 2
+        x, H, W = self.patch_embed2(x)
+        for i, blk in enumerate(self.block2):
+            x = blk(x, H, W)
+        x = self.norm2(x)
+        x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous()
+        outs.append(x)
+
+        # stage 3
+        x, H, W = self.patch_embed3(x)
+        for i, blk in enumerate(self.block3):
+            x = blk(x, H, W)
+        x = self.norm3(x)
+        x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous()
+        outs.append(x)
+
+        # stage 4
+        x, H, W = self.patch_embed4(x)
+        for i, blk in enumerate(self.block4):
+            x = blk(x, H, W)
+        x = self.norm4(x)
+        if not self.output_avg:
+            x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous()
+        outs.append(x)
+
+        return outs
+
+    def forward(self, x):
+        x = self.forward_features(x)
+    
+        if self.output_avg:
+            x = x[3].mean(dim=1)
+
+        return x
+
+
+class DWConv(nn.Module):
+    def __init__(self, dim=768):
+        super(DWConv, self).__init__()
+        self.dwconv = nn.Conv2d(dim, dim, 3, 1, 1, bias=True, groups=dim)
+
+    def forward(self, x, H, W):
+        B, N, C = x.shape
+        x = x.transpose(1, 2).view(B, C, H, W)
+        x = self.dwconv(x)
+        x = x.flatten(2).transpose(1, 2)
+
+        return x
+
+class mit_b0(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b0, self).__init__(
+            patch_size=4, embed_dims=[32, 64, 160, 256], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[2, 2, 2, 2], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+
+class mit_b1(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b1, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[2, 2, 2, 2], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+
+class mit_b2(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b2, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 4, 6, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+ 
+class mit_b3(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b3, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 4, 18, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+class mit_b3_avg(MixVisionTransformer):
+    def __init__(self, drop_path_rate=0.1, **kwargs):
+        super(mit_b3_avg, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 4, 18, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=drop_path_rate, output_avg=True)
+
+class mit_b4(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b4, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 8, 27, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+class mit_b5(MixVisionTransformer):
+    def __init__(self, **kwargs):
+        super(mit_b5, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 6, 40, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=0.1)
+
+class mit_b5_avg(MixVisionTransformer):
+    def __init__(self, drop_path_rate=0.1, **kwargs):
+        super(mit_b5_avg, self).__init__(
+            patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4],
+            qkv_bias=True, norm_layer=partial(LayerNorm, eps=1e-6), depths=[3, 6, 40, 3], sr_ratios=[8, 4, 2, 1],
+            drop_rate=0.0, drop_path_rate=drop_path_rate, output_avg=True)
+

megatron/model/vision/utils.py

+import warnings
+import torch
+import torch.nn.functional as F
+
+
+def resize(input,
+           size=None,
+           scale_factor=None,
+           mode='nearest',
+           align_corners=None,
+           warning=True):
+    if warning:
+        if size is not None and align_corners:
+            input_h, input_w = tuple(int(x) for x in input.shape[2:])
+            output_h, output_w = tuple(int(x) for x in size)
+            if output_h > input_h or output_w > output_h:
+                if ((output_h > 1 and output_w > 1 and input_h > 1
+                     and input_w > 1) and (output_h - 1) % (input_h - 1)
+                        and (output_w - 1) % (input_w - 1)):
+                    warnings.warn(
+                        f'When align_corners={align_corners}, '
+                        'the output would more aligned if '
+                        f'input size {(input_h, input_w)} is `x+1` and '
+                        f'out size {(output_h, output_w)} is `nx+1`')
+    if isinstance(size, torch.Size):
+        size = tuple(int(x) for x in size)
+    return F.interpolate(input, size, scale_factor, mode, align_corners)

megatron/model/vision/vit_backbone.py

@@ -147,7 +147,8 @@ class VitBackbone(MegatronModule):
                  pre_process=True,
                  post_process=True,
                  class_token=True,
-                 single_token_output=False):
+                 single_token_output=False,
+                 drop_path_rate=0.0):
         super(VitBackbone, self).__init__(share_word_embeddings=False)
         args = get_args()
 
@@ -170,6 +171,7 @@ class VitBackbone(MegatronModule):
         self.img_w = args.img_w
         self.micro_batch_size = args.micro_batch_size
         self.single_token_output = single_token_output
+        self.drop_path_rate = drop_path_rate
 
         assert self.img_h % self.patch_dim == 0
         assert self.img_w % self.patch_dim == 0
@@ -216,6 +218,7 @@ class VitBackbone(MegatronModule):
             self.scaled_init_method,
             pre_process=self.pre_process,
             post_process=self.post_process,
+            drop_path_rate=self.drop_path_rate
         )
 
     def set_input_tensor(self, input_tensor):

megatron/training.py

@@ -21,7 +21,6 @@ import sys
 import time
 # The earliest we can measure the start time.
 _TRAIN_START_TIME = time.time()
-
 import torch
 from torch.nn.parallel.distributed import DistributedDataParallel as torchDDP
 
@@ -51,7 +50,7 @@ from megatron.data.data_samplers import build_pretraining_data_loader
 from megatron.utils import calc_params_l2_norm
 from megatron.schedules import get_forward_backward_func
 from megatron.utils import report_memory
-
+from megatron.model.vision.knn_monitor import compute_feature_bank
 
 
 def print_datetime(string):
@@ -465,11 +464,23 @@ def train_step(forward_step_func, data_iterator,
         torch.distributed.all_reduce(grad, group=mpu.get_position_embedding_group())
     timers('backward-embedding-all-reduce').stop()
 
+    if args.vision_pretraining and args.vision_pretraining_type == "dino":
+        unwrapped_model = unwrap_model(model[0],
+                                       (torchDDP, LocalDDP, Float16Module))
+        unwrapped_model.cancel_gradients_last_layer(args.curr_iteration)
+
+
     # Update parameters.
     timers('optimizer').start()
     update_successful, grad_norm, num_zeros_in_grad = optimizer.step()
     timers('optimizer').stop()
 
+    if args.vision_pretraining and args.vision_pretraining_type == "dino":
+        unwrapped_model = unwrap_model(model[0],
+                                       (torchDDP, LocalDDP, Float16Module))
+        unwrapped_model.update_momentum(args.curr_iteration)
+
+
     # Update learning rate.
     if update_successful:
         increment = get_num_microbatches() * \
@@ -702,6 +713,7 @@ def train(forward_step_func, model, optimizer, opt_param_scheduler,
     report_memory_flag = True
     while iteration < args.train_iters:
         update_num_microbatches(args.consumed_train_samples)
+        args.curr_iteration = iteration
         loss_dict, skipped_iter, grad_norm, num_zeros_in_grad = \
             train_step(forward_step_func,
                        train_data_iterator,
@@ -791,6 +803,9 @@ def evaluate(forward_step_func,
     """Evaluation."""
     args = get_args()
 
+    if args.vision_pretraining and args.vision_pretraining_type == "dino":
+        compute_feature_bank(model)
+
     # Turn on evaluation mode which disables dropout.
     for model_module in model:
         model_module.eval()

pretrain_vit.py → pretrain_vision_classify.py

@@ -22,20 +22,32 @@ from megatron import get_args, get_timers, mpu, print_rank_0
 from megatron.data.vit_dataset import build_train_valid_datasets
 from megatron.model import ModelType
 from megatron.model.vision.classification import VitClassificationModel
+from megatron.model.vision.classification import MitClassificationModel
 from megatron.training import pretrain
 from megatron.utils import average_losses_across_data_parallel_group
 
+
 def model_provider(pre_process=True, post_process=True):
     """Build the model."""
 
-    print_rank_0("building VIT model ...")
     args = get_args()
 
-    model = VitClassificationModel(num_classes=args.num_classes,
-                                   pre_process=pre_process,
-                                   post_process=post_process)
+    if args.vision_backbone_type == 'vit':
+        print_rank_0("building VIT model ...")
+        model = VitClassificationModel(num_classes=args.num_classes,
+                                       pre_process=pre_process,
+                                       post_process=post_process)
+    elif args.vision_backbone_type == 'mit':
+        print_rank_0("building MIT model ...")
+        model = MitClassificationModel(num_classes=args.num_classes,
+                                       pre_process=pre_process,
+                                       post_process=post_process)
+    else:
+        raise Exception('{} vision backbone is not supported.'.format(
+                              args.vision_backbone_type))
     return model
 
+
 def get_batch(data_iterator):
     """Build the batch."""
     data = next(data_iterator)
@@ -46,6 +58,7 @@ def get_batch(data_iterator):
 
     return images, labels
 
+
 def loss_func(labels, output_tensor):
     logits = output_tensor.contiguous().float()
     loss = F.cross_entropy(logits, labels)
@@ -58,6 +71,7 @@ def loss_func(labels, output_tensor):
 
     return loss, {"loss": averaged_loss[0], "accuracy": averaged_loss[1]}
 
+
 def forward_step(data_iterator, model):
     """Forward step."""
     timers = get_timers()
@@ -98,5 +112,5 @@ if __name__ == "__main__":
         model_provider,
         ModelType.encoder_or_decoder,
         forward_step,
-        args_defaults={'dataloader_type': 'cyclic'}
+        args_defaults={'dataloader_type': 'cyclic', 'vision_pretraining': True}
     )

pretrain_vision_dino.py

+# coding=utf-8
+# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import torch
+import torch.nn.functional as F
+import torch.nn as nn
+import numpy as np
+import torch.distributed as dist
+from functools import partial
+from megatron import get_args, get_timers, mpu, print_rank_0
+from megatron.data.vit_dataset import build_train_valid_datasets
+from megatron.model.vision.dino import DINOPretrainModel
+from megatron.model.vision.knn_monitor import knn_predict, get_feature_bank
+from megatron.training import pretrain
+from megatron.utils import average_losses_across_data_parallel_group, unwrap_model
+from torch.nn.parallel.distributed import DistributedDataParallel as torchDDP
+from megatron.model import DistributedDataParallel as LocalDDP
+from megatron.model import Float16Module
+from megatron.model import ModelType
+
+def model_provider(pre_process=True, post_process=True):
+    """Build the model."""
+    return DINOPretrainModel(pre_process=pre_process, post_process=post_process)
+
+def get_batch(data_iterator):
+    """Build the batch."""
+    data = next(data_iterator)
+
+    # only data parallelism; no need for broadcast
+    if isinstance(data[0], list):
+        images = [aug.cuda() for aug in data[0]]
+    else:
+        images = data[0].cuda()
+    labels = data[1].cuda()
+
+    return images, labels
+
+
+def loss_func(model, labels, output_tensor, collect_data=False):
+    args = get_args()
+    
+    model = unwrap_model(
+        model,
+        (torchDDP, LocalDDP, Float16Module)
+    )
+    if model.training:
+        student_output, teacher_output = output_tensor
+        loss = model.dino_loss(student_output, teacher_output, args.curr_iteration)
+        averaged_loss = average_losses_across_data_parallel_group([loss])
+        return loss, {"loss": averaged_loss[0]}
+    else:
+        _, teacher_feature = output_tensor
+        feature_bank, feature_labels, classes = get_feature_bank()
+        feature = F.normalize(teacher_feature.float(), dim=1)
+
+        knn_accs = []
+        for k in [10, 20, 100, 200]:
+            pred_labels = knn_predict(feature, feature_bank,
+                                      feature_labels, classes, k, 0.07)
+            knn_acc = (pred_labels[:, 0] == labels).float().mean()
+            knn_accs.append(knn_acc)
+
+        averaged_loss = average_losses_across_data_parallel_group(knn_accs)
+        return 0, {"knn_acc_10": averaged_loss[0],
+                   "knn_acc_20": averaged_loss[1],
+                   "knn_acc_100": averaged_loss[2],
+                   "knn_acc_200": averaged_loss[3]}
+
+
+def forward_step(data_iterator, model):
+    """Forward step."""
+    timers = get_timers()
+
+    # Get the batch.
+    timers("batch-generator").start()
+    (
+        images,
+        labels,
+    ) = get_batch(data_iterator)
+    timers("batch-generator").stop()
+
+    return model(images), partial(loss_func, model, labels)
+
+
+def train_valid_test_datasets_provider(train_val_test_num_samples):
+    """Build train, valid, and test datasets."""
+    args = get_args()
+
+    print_rank_0(
+        "> building train, validation, and test datasets " "for VIT ..."
+    )
+    train_ds, valid_ds = build_train_valid_datasets(
+        data_path=args.data_path,
+        image_size=(args.img_h, args.img_w)
+    )
+    print_rank_0("> finished creating VIT datasets ...")
+
+    return train_ds, valid_ds, None
+
+
+if __name__ == "__main__":
+    pretrain(
+        train_valid_test_datasets_provider,
+        model_provider,
+        ModelType.encoder_or_decoder,
+        forward_step,
+        args_defaults={'dataloader_type': 'cyclic', 'vision_pretraining': True}
+    )
+

pretrain_vision_inpaint.py

+# coding=utf-8
+# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Pretrain VIT"""
+
+import torch
+import torch.nn.functional as F
+from functools import partial
+from megatron import get_args, get_timers, mpu, print_rank_0, print_rank_last
+from megatron.data.vit_dataset import build_train_valid_datasets
+from megatron.model.vision.inpainting import VitInpaintingModel
+from megatron.model.vision.inpainting import MitInpaintingModel
+from megatron.training import pretrain
+from megatron.utils import average_losses_across_data_parallel_group
+from tasks.vision.metrics import SSIM, PSNR
+from megatron.model import ModelType
+
+def model_provider(pre_process=True, post_process=True):
+    """Build the model."""
+    args = get_args()
+    if args.vision_backbone_type == 'vit':
+        model = VitInpaintingModel(pre_process=pre_process,
+                                   post_process=post_process)
+    elif args.vision_backbone_type == 'mit':
+        model = MitInpaintingModel(pre_process=pre_process,
+                                   post_process=post_process)
+    else:
+        raise Exception('{} vision backbone is not supported.'.format(
+                              args.vision_backbone_type))
+    return model
+
+
+def get_batch(data_iterator):
+    """Build the batch."""
+    data = next(data_iterator)
+
+    # only data parallelism; no need for broadcast
+    images = data[0][0].cuda()
+    masks = data[0][1].cuda()
+    return images, masks
+
+
+def loss_func(images, masks, masked_images, outputs, collect_data=False):
+    outputs = outputs.contiguous().float()
+    masks_flip = 1-masks
+    flip_masked_outputs = outputs.masked_fill(masks_flip.bool(), 0)
+    flip_masked_images = images.masked_fill(masks_flip.bool(), 0)
+
+    ssim_fun = SSIM()
+    psnr_fun = PSNR()
+
+    if not collect_data:
+        mask_count = torch.count_nonzero(masks)
+        loss = F.mse_loss(
+            flip_masked_outputs,
+            flip_masked_images.float(),
+            reduction="sum"
+        )
+        loss = loss/mask_count
+        ssim = ssim_fun(flip_masked_outputs, flip_masked_images.float())
+        psnr = psnr_fun(flip_masked_outputs, flip_masked_images.float())
+
+        averaged_loss = average_losses_across_data_parallel_group(
+            [loss, psnr, ssim]
+        )
+
+        return loss, {"loss": averaged_loss[0],
+                      "psnr": averaged_loss[1],
+                      'ssim': averaged_loss[2]}
+    else:
+        synth_images = masked_images.float() + flip_masked_outputs
+        ssim = ssim_fun(synth_images, images.float())
+        psnr = psnr_fun(synth_images, images.float())
+        return torch.cat((images, masked_images, synth_images), dim=2), ssim, psnr
+
+
+def forward_step(data_iterator, model):
+    """Forward step."""
+    timers = get_timers()
+
+    # Get the batch.
+    timers("batch-generator").start()
+    (
+        images,
+        masks,
+    ) = get_batch(data_iterator)
+    timers("batch-generator").stop()
+
+    masked_images = images.masked_fill(masks.bool(), 0)
+    outputs = model(masked_images)
+
+    # Forward mode
+    return outputs, partial(loss_func, images, masks, masked_images)
+
+
+def process_non_loss_data(data, iteration, writer):
+    psnr_sum = 0
+    ssim_sum = 0
+    for (output_tb, ssim, psnr) in data:
+        output_tb[output_tb < 0] = 0
+        output_tb[output_tb > 1] = 1
+        writer.add_images("gt-input-output-vald", output_tb,
+                          global_step=iteration, walltime=None,
+                          dataformats='NCHW')
+        psnr_sum = psnr_sum + psnr.item()
+        ssim_sum = ssim_sum + ssim.item()
+    psnr = psnr_sum/len(data)
+    ssim = ssim_sum/len(data)
+    writer.add_scalar('PSNR generate value-validation', psnr, iteration)
+    writer.add_scalar('SSIM generate value-validation', ssim, iteration)
+
+
+def train_valid_test_datasets_provider(train_val_test_num_samples):
+    """Build train, valid, and test datasets."""
+    args = get_args()
+
+    print_rank_0(
+        "> building train, validation, and test datasets " "for VIT ..."
+    )
+    train_ds, valid_ds = build_train_valid_datasets(
+        data_path=args.data_path,
+        image_size=(args.img_h, args.img_w)
+    )
+    print_rank_0("> finished creating VIT datasets ...")
+
+    return train_ds, valid_ds, None
+
+
+if __name__ == "__main__":
+
+    pretrain(
+        train_valid_test_datasets_provider,
+        model_provider,
+        ModelType.encoder_or_decoder,
+        forward_step,
+        process_non_loss_data,
+        args_defaults={'dataloader_type': 'cyclic', 'vision_pretraining': True}
+    )