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| 1 | +# Copyright (c) 2024 PaddlePaddle Authors. All Rights Reserved. |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +# you may not use this file except in compliance with the License. |
| 5 | +# You may obtain a copy of the License at |
| 6 | +# |
| 7 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +# See the License for the specific language governing permissions and |
| 13 | +# limitations under the License. |
| 14 | +import copy |
| 15 | +import os |
| 16 | + |
| 17 | +import paddle |
| 18 | +import paddle.nn as nn |
| 19 | +import paddle.nn.functional as F |
| 20 | +from paddle.distributed import fleet |
| 21 | +from paddle.distributed.fleet.meta_parallel import ParallelCrossEntropy |
| 22 | + |
| 23 | +from paddlenlp.transformers import ( |
| 24 | + AllGatherVarlenOp, |
| 25 | + fused_head_and_loss_fn, |
| 26 | + parallel_linear, |
| 27 | + parallel_matmul, |
| 28 | + sequence_parallel_sparse_mask_labels, |
| 29 | +) |
| 30 | +from paddlenlp.utils import infohub |
| 31 | + |
| 32 | + |
| 33 | +class KTOCriterion(nn.Layer): |
| 34 | + """KTO Criterion""" |
| 35 | + |
| 36 | + def __init__(self, config, kto_config=None, ignore_label=0, use_infohub=False): |
| 37 | + super(KTOCriterion, self).__init__() |
| 38 | + self.config = config |
| 39 | + if kto_config is None: |
| 40 | + if getattr(self.config, "kto_config", None) is None: |
| 41 | + raise ValueError("KTO Criterion requires model_config.kto_config.") |
| 42 | + self.kto_config = copy.deepcopy(config.kto_config) |
| 43 | + else: |
| 44 | + self.kto_config = kto_config |
| 45 | + if self.config.tensor_parallel_output and self.config.tensor_parallel_degree > 1: |
| 46 | + self.logprobs = ParallelCrossEntropy() |
| 47 | + else: |
| 48 | + self.logprobs = nn.CrossEntropyLoss(reduction="none") |
| 49 | + self.use_infohub = use_infohub |
| 50 | + self.ignore_label = ignore_label |
| 51 | + # allgather kl in criterion |
| 52 | + topo = fleet.get_hybrid_communicate_group()._topo |
| 53 | + parallel_groups = topo.get_comm_list("pipe") |
| 54 | + ranks = [] |
| 55 | + for group in parallel_groups: |
| 56 | + ranks.append(group[-1]) |
| 57 | + self.comm_group = paddle.distributed.new_group(ranks=ranks) |
| 58 | + |
| 59 | + def _nested_gather(self, tensors): |
| 60 | + """ |
| 61 | + Gather value of `tensors` (tensor or list/tuple of nested tensors) and convert them to numpy before |
| 62 | + concatenating them to `gathered` |
| 63 | + """ |
| 64 | + local_rank = -1 |
| 65 | + env_local_rank = int(os.environ.get("PADDLE_RANK_IN_NODE", -1)) |
| 66 | + if env_local_rank != -1 and env_local_rank != local_rank and paddle.distributed.get_world_size() > 1: |
| 67 | + local_rank = env_local_rank |
| 68 | + if tensors is None: |
| 69 | + return |
| 70 | + if local_rank != -1: |
| 71 | + output_tensors = [] |
| 72 | + paddle.distributed.all_gather( |
| 73 | + output_tensors, paddle.tile(tensors, repeat_times=[1, 1]), group=self.comm_group |
| 74 | + ) |
| 75 | + tensors = paddle.concat(output_tensors, axis=0) |
| 76 | + return tensors |
| 77 | + |
| 78 | + def kto_logps(self, logits, response_labels, response_kl_labels, response_indexs): |
| 79 | + """KTO logprobs""" |
| 80 | + labels = response_labels + response_kl_labels |
| 81 | + if self.config.use_fused_head_and_loss_fn: |
| 82 | + hidden_states, weight, bias, transpose_y = logits |
| 83 | + elif self.config.use_sparse_head_and_loss_fn: |
| 84 | + hidden_states, weight, bias = logits |
| 85 | + if self.config.use_sparse_head_and_loss_fn: |
| 86 | + if self.config.tensor_parallel_degree > 1 and self.config.sequence_parallel: |
| 87 | + labels, sparse_tgt_idx = sequence_parallel_sparse_mask_labels(labels, self.ignore_label) |
| 88 | + |
| 89 | + hidden_states = paddle.take_along_axis(hidden_states, sparse_tgt_idx, axis=0) |
| 90 | + hidden_states = AllGatherVarlenOp.apply(hidden_states) |
| 91 | + else: |
| 92 | + labels = labels.flatten() |
| 93 | + sparse_tgt_idx = paddle.nonzero(labels != self.ignore_label).flatten() |
| 94 | + labels = paddle.take_along_axis(labels, sparse_tgt_idx, axis=0) |
| 95 | + |
| 96 | + hidden_states = hidden_states.reshape([-1, hidden_states.shape[-1]]) |
| 97 | + hidden_states = paddle.take_along_axis(hidden_states, sparse_tgt_idx.unsqueeze(-1), axis=0) |
| 98 | + if self.config.use_fused_head_and_loss_fn: |
| 99 | + per_token_logps = -fused_head_and_loss_fn( |
| 100 | + hidden_states, |
| 101 | + weight, |
| 102 | + bias, |
| 103 | + labels, |
| 104 | + None, |
| 105 | + transpose_y, |
| 106 | + self.config.vocab_size, |
| 107 | + self.config.tensor_parallel_degree, |
| 108 | + self.config.tensor_parallel_output, |
| 109 | + self.config.fused_linear, |
| 110 | + getattr(self.config, "chunk_size", 1024), |
| 111 | + return_token_loss=True, |
| 112 | + ignore_index=self.ignore_label, |
| 113 | + ) |
| 114 | + elif self.config.use_sparse_head_and_loss_fn: |
| 115 | + if bias is None: |
| 116 | + logits = parallel_matmul(hidden_states, weight, self.config.tensor_parallel_output) |
| 117 | + else: |
| 118 | + logits = parallel_linear( |
| 119 | + hidden_states, |
| 120 | + weight, |
| 121 | + bias, |
| 122 | + self.config.tensor_parallel_output, |
| 123 | + ) |
| 124 | + logits = logits.astype("float32") |
| 125 | + per_token_logps = -self.logprobs(logits, labels) |
| 126 | + else: |
| 127 | + logits = logits.astype("float32") |
| 128 | + if logits.shape[:-1] != labels.shape: |
| 129 | + raise ValueError("Logits (batch and sequence length dim) and labels must have the same shape.") |
| 130 | + # bs, seq |
| 131 | + per_token_logps = -self.logprobs(logits, labels.unsqueeze(2)).squeeze(2) |
| 132 | + |
| 133 | + if len(response_indexs.shape) == 3: |
| 134 | + response_indexs = response_indexs[0] |
| 135 | + if self.config.use_sparse_head_and_loss_fn: |
| 136 | + chosen_logps_list = [ |
| 137 | + (per_token_logps[response_index[1] : response_index[2]]).sum() |
| 138 | + for response_index in response_indexs |
| 139 | + if response_index[4] == 1 |
| 140 | + ] |
| 141 | + rejected_logps_list = [ |
| 142 | + (per_token_logps[response_index[1] : response_index[2]]).sum() |
| 143 | + for response_index in response_indexs |
| 144 | + if response_index[4] == 0 |
| 145 | + ] |
| 146 | + kl_logps_list = [ |
| 147 | + (per_token_logps[response_index[2] : response_index[3]]).sum() for response_index in response_indexs |
| 148 | + ] |
| 149 | + else: |
| 150 | + chosen_logps_list = [ |
| 151 | + (per_token_logps[response_index[0]][response_index[1] : response_index[2]]).sum() |
| 152 | + for response_index in response_indexs |
| 153 | + if response_index[4] == 1 |
| 154 | + ] |
| 155 | + rejected_logps_list = [ |
| 156 | + (per_token_logps[response_index[0]][response_index[1] : response_index[2]]).sum() |
| 157 | + for response_index in response_indexs |
| 158 | + if response_index[4] == 0 |
| 159 | + ] |
| 160 | + kl_logps_list = [ |
| 161 | + (per_token_logps[response_index[0]][response_index[2] : response_index[3]]).sum() |
| 162 | + for response_index in response_indexs |
| 163 | + ] |
| 164 | + if len(chosen_logps_list) == 0: |
| 165 | + chosen_logps = paddle.zeros([0], dtype="float32") |
| 166 | + else: |
| 167 | + chosen_logps = paddle.stack(chosen_logps_list, axis=0) |
| 168 | + if len(rejected_logps_list) == 0: |
| 169 | + rejected_logps = paddle.zeros([0], dtype="float32") |
| 170 | + else: |
| 171 | + rejected_logps = paddle.stack(rejected_logps_list, axis=0) |
| 172 | + kl_logps = paddle.stack(kl_logps_list, axis=0) |
| 173 | + return chosen_logps, rejected_logps, kl_logps |
| 174 | + |
| 175 | + def kto_loss( |
| 176 | + self, |
| 177 | + policy_chosen_logps, |
| 178 | + policy_rejected_logps, |
| 179 | + policy_kl_logps, |
| 180 | + reference_chosen_logps, |
| 181 | + reference_rejected_logps, |
| 182 | + reference_kl_logps, |
| 183 | + ): |
| 184 | + """KTO Loss""" |
| 185 | + kl = (policy_kl_logps - reference_kl_logps).mean().detach() |
| 186 | + kl = self._nested_gather(paddle.tile(kl, repeat_times=[1, 1])).mean().clip(min=0) |
| 187 | + if policy_chosen_logps.shape[0] == 0 or reference_chosen_logps.shape[0] == 0: |
| 188 | + chosen_losses = paddle.zeros([0]) |
| 189 | + else: |
| 190 | + chosen_logratios = policy_chosen_logps - reference_chosen_logps |
| 191 | + chosen_losses = 1 - F.sigmoid(self.kto_config.beta * (chosen_logratios - kl)) |
| 192 | + if policy_rejected_logps.shape[0] == 0 or reference_rejected_logps.shape[0] == 0: |
| 193 | + rejected_losses = paddle.zeros([0]) |
| 194 | + else: |
| 195 | + rejected_logratios = policy_rejected_logps - reference_rejected_logps |
| 196 | + rejected_losses = 1 - F.sigmoid(self.kto_config.beta * (kl - rejected_logratios)) |
| 197 | + losses = paddle.concat( |
| 198 | + ( |
| 199 | + self.kto_config.desirable_weight * chosen_losses, |
| 200 | + self.kto_config.undesirable_weight * rejected_losses, |
| 201 | + ), |
| 202 | + 0, |
| 203 | + ) |
| 204 | + return losses.mean(), kl |
| 205 | + |
| 206 | + def forward( |
| 207 | + self, |
| 208 | + logits, |
| 209 | + labels, |
| 210 | + ): |
| 211 | + """Forward""" |
| 212 | + ( |
| 213 | + response_labels, |
| 214 | + response_kl_labels, |
| 215 | + response_indexs, |
| 216 | + reference_chosen_logps, |
| 217 | + reference_rejected_logps, |
| 218 | + reference_kl_logps, |
| 219 | + ) = labels |
| 220 | + if reference_chosen_logps is None or reference_rejected_logps is None or reference_kl_logps is None: |
| 221 | + ( |
| 222 | + reference_chosen_logps, |
| 223 | + reference_rejected_logps, |
| 224 | + reference_kl_logps, |
| 225 | + ) = self.kto_logps(logits, response_labels, response_kl_labels, response_indexs) |
| 226 | + if self.use_infohub: |
| 227 | + infohub.reference_chosen_logps.append(reference_chosen_logps) |
| 228 | + infohub.reference_rejected_logps.append(reference_rejected_logps) |
| 229 | + infohub.reference_kl_logps.append(reference_kl_logps) |
| 230 | + # pipeline mode requires return loss when self._compute_loss is True |
| 231 | + return paddle.zeros([1]) |
| 232 | + else: |
| 233 | + return ( |
| 234 | + reference_chosen_logps, |
| 235 | + reference_rejected_logps, |
| 236 | + reference_kl_logps, |
| 237 | + ) |
| 238 | + policy_chosen_logps, policy_rejected_logps, policy_kl_logps = self.kto_logps( |
| 239 | + logits, response_labels, response_kl_labels, response_indexs |
| 240 | + ) |
| 241 | + loss, kl = self.kto_loss( |
| 242 | + policy_chosen_logps, |
| 243 | + policy_rejected_logps, |
| 244 | + policy_kl_logps, |
| 245 | + reference_chosen_logps, |
| 246 | + reference_rejected_logps, |
| 247 | + reference_kl_logps, |
| 248 | + ) |
| 249 | + if self.use_infohub: |
| 250 | + infohub.policy_chosen_logps.append(policy_chosen_logps.detach()) |
| 251 | + infohub.policy_rejected_logps.append(policy_rejected_logps.detach()) |
| 252 | + infohub.policy_kl_logps.append(policy_kl_logps.detach()) |
| 253 | + infohub.kl.append(kl.detach()) |
| 254 | + return loss |
| 255 | + else: |
| 256 | + return ( |
| 257 | + policy_chosen_logps, |
| 258 | + policy_rejected_logps, |
| 259 | + policy_kl_logps, |
| 260 | + loss, |
| 261 | + kl, |
| 262 | + ) |
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