File size: 4,702 Bytes
a93e458 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 |
# Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
"""Pretrain BERT"""
from functools import partial
import torch
import torch.nn.functional as F
import megatron.initialize
import megatron
from megatron import get_args
from megatron import print_rank_0
from megatron import get_timers
from megatron.core import tensor_parallel
from megatron.data.dataset_utils import build_train_valid_test_datasets
from megatron.model import BertModel, ModelType
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 BERT model ...')
args = get_args()
num_tokentypes = 2 if args.bert_binary_head else 0
model_type_bert = ModelType.encoder_or_decoder
model = BertModel(
num_tokentypes=num_tokentypes,
add_binary_head=args.bert_binary_head,
parallel_output=True,
pre_process=pre_process,
post_process=post_process,
model_type=model_type_bert)
return model
def get_batch(data_iterator):
"""Build the batch."""
# Items and their type.
keys = ['text', 'types', 'labels', 'is_random', 'loss_mask', 'padding_mask']
datatype = torch.int64
# Broadcast data.
if data_iterator is not None:
data = next(data_iterator)
else:
data = None
data_b = tensor_parallel.broadcast_data(keys, data, datatype)
# Unpack.
tokens = data_b['text'].long()
types = data_b['types'].long()
sentence_order = data_b['is_random'].long()
loss_mask = data_b['loss_mask'].float()
lm_labels = data_b['labels'].long()
padding_mask = data_b['padding_mask'].long()
return tokens, types, sentence_order, loss_mask, lm_labels, padding_mask
def loss_func(loss_mask, sentence_order, output_tensor):
lm_loss_, sop_logits = output_tensor
lm_loss_ = lm_loss_.float()
loss_mask = loss_mask.float()
lm_loss = torch.sum(
lm_loss_.view(-1) * loss_mask.reshape(-1)) / loss_mask.sum()
if sop_logits is not None:
sop_loss = F.cross_entropy(sop_logits.view(-1, 2).float(),
sentence_order.view(-1),
ignore_index=-1)
sop_loss = sop_loss.float()
loss = lm_loss + sop_loss
averaged_losses = average_losses_across_data_parallel_group(
[lm_loss, sop_loss])
return loss, {'lm loss': averaged_losses[0],
'sop loss': averaged_losses[1]}
else:
loss = lm_loss
averaged_losses = average_losses_across_data_parallel_group(
[lm_loss])
return loss, {'lm loss': averaged_losses[0]}
def forward_step(data_iterator, model):
"""Forward step."""
args = get_args()
timers = get_timers()
# Get the batch.
timers('batch-generator', log_level=2).start()
tokens, types, sentence_order, loss_mask, lm_labels, padding_mask = get_batch(
data_iterator)
timers('batch-generator').stop()
if not args.bert_binary_head:
types = None
# Forward pass through the model.
output_tensor = model(tokens, padding_mask, tokentype_ids=types,
lm_labels=lm_labels)
return output_tensor, partial(loss_func, loss_mask, sentence_order)
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 BERT ...')
train_ds, valid_ds, test_ds = build_train_valid_test_datasets(
data_prefix=args.data_path,
data_impl=args.data_impl,
splits_string=args.split,
train_valid_test_num_samples=train_val_test_num_samples,
max_seq_length=args.seq_length,
masked_lm_prob=args.mask_prob,
short_seq_prob=args.short_seq_prob,
seed=args.seed,
skip_warmup=(not args.mmap_warmup),
binary_head=args.bert_binary_head)
print_rank_0("> finished creating BERT datasets ...")
return train_ds, valid_ds, test_ds
if __name__ == "__main__":
model_type_bert = ModelType.encoder_or_decoder
args_defaults = {'tokenizer_type': 'BertWordPieceLowerCase'}
megatron.initialize.initialize_megatron(extra_args_provider=None,
args_defaults=args_defaults)
args = megatron.get_args()
megatron.training.pretrain(args,
train_valid_test_datasets_provider,
model_provider,
model_type_bert,
forward_step)
|