333 lines
10 KiB
Python
Executable File
333 lines
10 KiB
Python
Executable File
# Copyright 2024 NVIDIA CORPORATION & AFFILIATES
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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# SPDX-License-Identifier: Apache-2.0
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"""
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This file contains primitives for multi-gpu communication.
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This is useful when doing distributed training.
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"""
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import gc
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import os
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import pickle
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import shutil
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import mmcv
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import torch
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import torch.distributed as dist
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from mmcv.runner import get_dist_info
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def is_distributed():
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return get_world_size() > 1
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def get_world_size():
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if not dist.is_available():
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return 1
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if not dist.is_initialized():
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return 1
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return dist.get_world_size()
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def get_rank():
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if not dist.is_available():
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return 0
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if not dist.is_initialized():
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return 0
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return dist.get_rank()
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def get_local_rank():
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if not dist.is_available():
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return 0
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if not dist.is_initialized():
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return 0
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local_rank = int(os.getenv("LOCAL_RANK", 0))
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return local_rank
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def is_master():
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return get_rank() == 0
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def is_local_master():
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return get_local_rank() == 0
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def get_local_proc_group(group_size=8):
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world_size = get_world_size()
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if world_size <= group_size or group_size == 1:
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return None
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assert (
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world_size % group_size == 0
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), f"world size ({world_size}) should be evenly divided by group size ({group_size})."
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process_groups = getattr(get_local_proc_group, "process_groups", dict())
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if group_size not in process_groups:
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num_groups = dist.get_world_size() // group_size
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groups = [list(range(i * group_size, (i + 1) * group_size)) for i in range(num_groups)]
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process_groups.update({group_size: [torch.distributed.new_group(group) for group in groups]})
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get_local_proc_group.process_groups = process_groups
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group_idx = get_rank() // group_size
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process_groups = get_local_proc_group.process_groups.get(group_size)[group_idx]
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return process_groups
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def synchronize():
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"""
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Helper function to synchronize (barrier) among all processes when
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using distributed training
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"""
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if not dist.is_available():
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return
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if not dist.is_initialized():
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return
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world_size = dist.get_world_size()
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if world_size == 1:
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return
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dist.barrier()
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def all_gather(data):
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"""
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Run all_gather on arbitrary picklable data (not necessarily tensors)
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Args:
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data: any picklable object
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Returns:
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list[data]: list of data gathered from each rank
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"""
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to_device = torch.device("cuda")
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# to_device = torch.device("cpu")
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world_size = get_world_size()
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if world_size == 1:
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return [data]
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# serialized to a Tensor
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buffer = pickle.dumps(data)
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storage = torch.ByteStorage.from_buffer(buffer)
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tensor = torch.ByteTensor(storage).to(to_device)
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# obtain Tensor size of each rank
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local_size = torch.LongTensor([tensor.numel()]).to(to_device)
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size_list = [torch.LongTensor([0]).to(to_device) for _ in range(world_size)]
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dist.all_gather(size_list, local_size)
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size_list = [int(size.item()) for size in size_list]
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max_size = max(size_list)
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# receiving Tensor from all ranks
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# we pad the tensor because torch all_gather does not support
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# gathering tensors of different shapes
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tensor_list = []
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for _ in size_list:
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tensor_list.append(torch.ByteTensor(size=(max_size,)).to(to_device))
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if local_size != max_size:
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padding = torch.ByteTensor(size=(max_size - local_size,)).to(to_device)
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tensor = torch.cat((tensor, padding), dim=0)
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dist.all_gather(tensor_list, tensor)
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data_list = []
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for size, tensor in zip(size_list, tensor_list):
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buffer = tensor.cpu().numpy().tobytes()[:size]
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data_list.append(pickle.loads(buffer))
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return data_list
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def reduce_dict(input_dict, average=True):
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"""
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Args:
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input_dict (dict): all the values will be reduced
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average (bool): whether to do average or sum
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Reduce the values in the dictionary from all processes so that process with rank
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0 has the averaged results. Returns a dict with the same fields as
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input_dict, after reduction.
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"""
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world_size = get_world_size()
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if world_size < 2:
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return input_dict
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with torch.no_grad():
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names = []
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values = []
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# sort the keys so that they are consistent across processes
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for k in sorted(input_dict.keys()):
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names.append(k)
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values.append(input_dict[k])
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values = torch.stack(values, dim=0)
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dist.reduce(values, dst=0)
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if dist.get_rank() == 0 and average:
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# only main process gets accumulated, so only divide by
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# world_size in this case
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values /= world_size
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reduced_dict = {k: v for k, v in zip(names, values)}
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return reduced_dict
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def broadcast(data, **kwargs):
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if get_world_size() == 1:
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return data
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data = [data]
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dist.broadcast_object_list(data, **kwargs)
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return data[0]
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def all_gather_cpu(result_part, tmpdir=None, collect_by_master=True):
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rank, world_size = get_dist_info()
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if tmpdir is None:
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tmpdir = "./tmp"
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if rank == 0:
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mmcv.mkdir_or_exist(tmpdir)
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synchronize()
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# dump the part result to the dir
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mmcv.dump(result_part, os.path.join(tmpdir, f"part_{rank}.pkl"))
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synchronize()
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# collect all parts
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if collect_by_master and rank != 0:
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return None
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else:
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# load results of all parts from tmp dir
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results = []
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for i in range(world_size):
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part_file = os.path.join(tmpdir, f"part_{i}.pkl")
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results.append(mmcv.load(part_file))
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if not collect_by_master:
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synchronize()
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# remove tmp dir
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if rank == 0:
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shutil.rmtree(tmpdir)
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return results
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def all_gather_tensor(tensor, group_size=None, group=None):
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if group_size is None:
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group_size = get_world_size()
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if group_size == 1:
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output = [tensor]
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else:
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output = [torch.zeros_like(tensor) for _ in range(group_size)]
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dist.all_gather(output, tensor, group=group)
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return output
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def gather_difflen_tensor(feat, num_samples_list, concat=True, group=None, group_size=None):
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world_size = get_world_size()
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if world_size == 1:
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if not concat:
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return [feat]
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return feat
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num_samples, *feat_dim = feat.size()
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# padding to max number of samples
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feat_padding = feat.new_zeros((max(num_samples_list), *feat_dim))
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feat_padding[:num_samples] = feat
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# gather
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feat_gather = all_gather_tensor(feat_padding, group=group, group_size=group_size)
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for r, num in enumerate(num_samples_list):
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feat_gather[r] = feat_gather[r][:num]
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if concat:
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feat_gather = torch.cat(feat_gather)
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return feat_gather
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class GatherLayer(torch.autograd.Function):
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"""Gather tensors from all process, supporting backward propagation."""
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@staticmethod
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def forward(ctx, input):
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ctx.save_for_backward(input)
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num_samples = torch.tensor(input.size(0), dtype=torch.long, device=input.device)
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ctx.num_samples_list = all_gather_tensor(num_samples)
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output = gather_difflen_tensor(input, ctx.num_samples_list, concat=False)
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return tuple(output)
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@staticmethod
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def backward(ctx, *grads): # tuple(output)'s grad
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(input,) = ctx.saved_tensors
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num_samples_list = ctx.num_samples_list
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rank = get_rank()
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start, end = sum(num_samples_list[:rank]), sum(num_samples_list[: rank + 1])
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grads = torch.cat(grads)
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if is_distributed():
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dist.all_reduce(grads)
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grad_out = torch.zeros_like(input)
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grad_out[:] = grads[start:end]
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return grad_out, None, None
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class GatherLayerWithGroup(torch.autograd.Function):
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"""Gather tensors from all process, supporting backward propagation."""
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@staticmethod
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def forward(ctx, input, group, group_size):
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ctx.save_for_backward(input)
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ctx.group_size = group_size
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output = all_gather_tensor(input, group=group, group_size=group_size)
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return tuple(output)
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@staticmethod
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def backward(ctx, *grads): # tuple(output)'s grad
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(input,) = ctx.saved_tensors
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grads = torch.stack(grads)
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if is_distributed():
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dist.all_reduce(grads)
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grad_out = torch.zeros_like(input)
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grad_out[:] = grads[get_rank() % ctx.group_size]
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return grad_out, None, None
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def gather_layer_with_group(data, group=None, group_size=None):
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if group_size is None:
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group_size = get_world_size()
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output = GatherLayer.apply(data, group, group_size)
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return output
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import math
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from typing import Union
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# from torch.distributed.fsdp.fully_sharded_data_parallel import TrainingState_, _calc_grad_norm
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@torch.no_grad()
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def clip_grad_norm_(self, max_norm: Union[float, int], norm_type: Union[float, int] = 2.0) -> None:
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self._lazy_init()
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self._wait_for_previous_optim_step()
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assert self._is_root, "clip_grad_norm should only be called on the root (parent) instance"
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self._assert_state(TrainingState_.IDLE)
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max_norm = float(max_norm)
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norm_type = float(norm_type)
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# Computes the max norm for this shard's gradients and sync's across workers
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local_norm = _calc_grad_norm(self.params_with_grad, norm_type).cuda() # type: ignore[arg-type]
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if norm_type == math.inf:
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total_norm = local_norm
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dist.all_reduce(total_norm, op=torch.distributed.ReduceOp.MAX, group=self.process_group)
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else:
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total_norm = local_norm**norm_type
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dist.all_reduce(total_norm, group=self.process_group)
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total_norm = total_norm ** (1.0 / norm_type)
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clip_coef = torch.tensor(max_norm, dtype=total_norm.dtype, device=total_norm.device) / (total_norm + 1e-6)
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if clip_coef < 1:
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# multiply by clip_coef, aka, (max_norm/total_norm).
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for p in self.params_with_grad:
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assert p.grad is not None
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p.grad.detach().mul_(clip_coef.to(p.grad.device))
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return total_norm
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def flush():
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gc.collect()
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torch.cuda.empty_cache()
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