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PPO 训练器
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开始使用
PPO 训练器
TRL 支持使用近端策略优化 (PPO) 训练大语言模型 (LLM)。
参考文献
开始使用
要运行 PPO 脚本以确保训练器可以运行，你可以运行以下命令，使用一个虚拟的奖励模型来训练 PPO 模型。
python examples/scripts/ppo/ppo.py \
--dataset_name trl-internal-testing/descriptiveness-sentiment-trl-style \
--dataset_train_split descriptiveness \
--learning_rate 3e-6 \
--num_ppo_epochs 1 \
--num_mini_batches 1 \
--output_dir models/minimal/ppo \
--per_device_train_batch_size 64 \
--gradient_accumulation_steps 1 \
--total_episodes 10000 \
--model_name_or_path EleutherAI/pythia-1b-deduped \
--sft_model_path EleutherAI/pythia-1b-deduped \
--reward_model_path EleutherAI/pythia-1b-deduped \
--missing_eos_penalty 1.0日志指标解释
记录的指标如下。这是一个在 Weights and Biases 上跟踪的运行示例
eps: 跟踪每秒的片段（episode）数。objective/kl: 当前策略和参考策略之间的平均库尔贝克-莱布勒（KL）散度。objective/entropy: 策略的平均熵，表示策略选择动作的随机性。objective/non_score_reward: 来自非分数相关来源的平均奖励，基本上是beta * kl.sum(1)，其中beta是 KL 惩罚系数，kl是每个词元的 KL 散度。objective/rlhf_reward: 平均 RLHF 奖励，即score - non_score_reward。objective/scores: 由奖励模型/环境返回的平均分数。policy/approxkl_avg: 连续 PPO 策略之间的平均近似 KL 散度。请注意，这与objective/kl不同。policy/clipfrac_avg: 被裁剪的策略更新的平均比例，表示策略更新被限制以防止大幅度变化的频率。loss/policy_avg: 平均策略损失，表示策略的表现如何。loss/value_avg: 平均价值损失，表示预测值与实际奖励之间的差异。val/clipfrac_avg: 被裁剪的价值函数更新的平均比例，与 policy/clipfrac_avg 类似，但针对价值函数。policy/entropy_avg: 训练期间策略的平均熵，表示策略动作的多样性。val/ratio: 当前策略概率与旧策略概率的平均比率，提供了策略变化程度的度量。val/ratio_var:val/ratio的方差，表示策略变化的可变性。val/num_eos_tokens: 生成的序列结束（EOS）词元的数量，可以表示完整响应的数量。lr: 学习率：优化器当前使用的学习率。episode: 轮次：训练过程中的当前轮次计数。
实用技巧
- 调试提示：
objective/rlhf_reward：这是 RLHF 训练的最终目标。如果训练按预期进行，这个指标应该持续上升。 - 调试提示：
val/ratio：这个数值应该在 1.0 左右浮动，并被 PPO 的代理损失函数中的--cliprange 0.2裁剪。所以如果这个ratio过高，比如 2.0 或 1000.0，或者过低，比如 0.1，意味着连续策略之间的更新过于剧烈。你应该尝试理解为什么会发生这种情况并尝试修复它。 - 内存提示：如果内存不足，可以尝试减少
--per_device_train_batch_size或增加--gradient_accumulation_steps来减少内存占用。 - 内存提示：如果你有多个 GPU，也可以使用 DeepSpeed stage 3 进行训练来减少内存占用
accelerate launch --config_file examples/accelerate_configs/deepspeed_zero3.yaml。 - 使用提示：我们推荐通过
--missing_eos_penalty使用“EOS 技巧”，它会对未以 EOS 标记结束的补全得分减去一个固定的标量惩罚。这可以帮助模型学习生成更连贯的补全。
我的模型到底在做什么？
为了帮助你理解模型正在做什么，我们会定期记录一些模型的样本补全。这是一个补全的例子。在一个在 Weights and Biases 上跟踪的运行示例中，它看起来如下，让你能看到模型在不同训练阶段的响应。默认情况下，我们在训练期间生成 --num_sample_generations 10 个样本，但你可以自定义生成的数量。
在日志中，采样的生成结果如下：
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━┓
┃ query ┃ model response ┃ score ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━┩
│ SUBREDDIT: r/AskReddit │ I'm in love with a friend, and │ 3.921875 │
│ │ I don't know how to get rid of │ │
│ TITLE: How do you get someone │ those feelings. I'm │ │
│ out of your head? │ desperate.<|endoftext|>[PAD][P… │ │
│ │ │ │
│ POST: Hi, │ │ │
│ I'm 22, and I have been with my │ │ │
│ girlfriend for 5 years now. We │ │ │
│ recently moved together. We've │ │ │
│ always loved each other │ │ │
│ intensely. │ │ │
│ │ │ │
│ Problem, I recently started to │ │ │
│ have feelings for an other │ │ │
│ person (a friend). This person │ │ │
│ has had a boyfriend for now 3 │ │ │
│ years, and has absolutely no │ │ │
│ ideas. Those feelings were so │ │ │
│ strong, it was hard to hide │ │ │
│ them. After 2 months of me │ │ │
│ being distant and really sad, │ │ │
│ my girlfriend forced me to say │ │ │
│ what was bothering me. I'm not │ │ │
│ a good liar, and now she knows. │ │ │
│ │ │ │
│ We decided to give us a week │ │ │
│ alone, I went to my parents. │ │ │
│ │ │ │
│ Now, I'm completely lost. I │ │ │
│ keep on thinking about this │ │ │
│ person, and I hate that. I │ │ │
│ would like for those feelings │ │ │
│ to go away, to leave me alone. │ │ │
│ But I can't. │ │ │
│ │ │ │
│ What do I do? It's been 3 │ │ │
│ months now, and I'm just │ │ │
│ desperate. │ │ │
│ │ │ │
│ TL;DR: │ │ │
├─────────────────────────────────┼─────────────────────────────────┼──────────┤
│ SUBREDDIT: r/pettyrevenge │ My mom woke me up with a loud │ 6.84375 │
│ │ TV. I blasted Gangnam Style on │ │
│ TITLE: So, my mom woke me up │ repeat, with the bass cranked │ │
│ with a loud TV. │ up as high as it could │ │
│ │ go.<|endoftext|>[PAD][PAD][PAD… │ │
│ POST: She was in her living │ │ │
│ room, watching TV. This was at │ │ │
│ about 8:30 in the morning, and │ │ │
│ she was exercising. She turned │ │ │
│ the TV up extra loud to hear it │ │ │
│ over her excercycle, and woke │ │ │
│ me up. I went in there asking │ │ │
│ for her to turn it down. She │ │ │
│ said she didn't have to; I │ │ │
│ explained that I always used │ │ │
│ headphones so she didn't have │ │ │
│ to deal with my noise and that │ │ │
│ she should give me a little │ │ │
│ more respect, given that I paid │ │ │
│ rent at the time. │ │ │
│ │ │ │
│ She disagreed. I went back to │ │ │
│ my room, rather pissed off at │ │ │
│ the lack of equality. I had no │ │ │
│ lock on my door; but I had a │ │ │
│ dresser right next to it, so I │ │ │
│ pulled one of the drawers out │ │ │
│ enough so that it caused the │ │ │
│ door to not be openable. Then, │ │ │
│ I turned my speakers up really │ │ │
│ loud and blasted Gangnam Style │ │ │
│ on repeat, with the bass │ │ │
│ cranked up as high as it could │ │ │
│ go. │ │ │
│ │ │ │
│ If you hate Gangnam Style for │ │ │
│ being overplayed, you will see │ │ │
│ why I chose that particular │ │ │
│ song. I personally don't mind │ │ │
│ it. But here's the thing about │ │ │
│ my bass; it vibrates the walls, │ │ │
│ making one hell of a lot of │ │ │
│ noise. Needless to say, my mom │ │ │
│ was not pleased and shut off │ │ │
│ the internet. But it was oh so │ │ │
│ worth it. │ │ │
│ │ │ │
│ TL;DR: │ │ │
└─────────────────────────────────┴─────────────────────────────────┴──────────┘实现细节
这个 PPO 实现基于使用 PPO 进行 RLHF 的 N+ 个实现细节：TL;DR 摘要案例研究。
基准实验
为了验证 PPO 实现的有效性，我们在 1B 参数模型上进行了实验。以下是我们用来运行实验的命令。我们直接从使用 PPO 进行 RLHF 的 N+ 个实现细节：TL;DR 摘要案例研究中获取 SFT / RM 模型。
accelerate launch --config_file examples/accelerate_configs/deepspeed_zero2.yaml \
examples/scripts/ppo/ppo_tldr.py \
--output_dir models/minimal/ppo_tldr \
--learning_rate 3e-6 \
--per_device_train_batch_size 16 \
--gradient_accumulation_steps 4 \
--total_episodes 1000000 \
--model_name_or_path EleutherAI/pythia-1b-deduped \
--sft_model_path cleanrl/EleutherAI_pythia-1b-deduped__sft__tldr \
--reward_model_path cleanrl/EleutherAI_pythia-1b-deduped__reward__tldr \
--local_rollout_forward_batch_size 16 \
--missing_eos_penalty 1.0 \
--stop_token eos检查点和实验跟踪可在以下链接查看：
为了评估，我们使用 vLLM 加载检查点，并使用 GPT-4o mini 作为评判模型，评估生成的 TL;DR 与参考 TL;DR。有关如何使用评判器的更多信息，请参见评判器。
$ python examples/scripts/evals/judge_tldr.py --model_name_or_path cleanrl/EleutherAI_pythia-1b-deduped__sft__tldr --judge_model gpt-4o-mini --num_examples 1000 Model win rate: 33.00% $ python examples/scripts/evals/judge_tldr.py --model_name_or_path vwxyzjn/ppo_tldr --judge_model gpt-4o-mini --num_examples 1000 Model win rate: 64.70%
PPO 检查点获得了 64.7% 的偏好率，而 SFT 检查点的偏好率为 33.0%。这是一个好迹象，表明 PPO 训练按预期工作。
指标
# pip install openrlbenchmark==0.2.1a5
# see https://github.com/openrlbenchmark/openrlbenchmark#get-started for documentation
# to use it, change `?we=huggingface&wpn=trl` to your own project and `?tag=pr-1540` to your own tag
python -m openrlbenchmark.rlops_multi_metrics \
--filters '?we=huggingface&wpn=trl&xaxis=train/episode&ceik=output_dir&cen=sft_model_path&metrics=train/objective/rlhf_reward&metrics=train/objective/scores&metrics=train/objective/kl&metrics=train/objective/non_score_reward&metrics=train/objective/entropy&metrics=train/policy/approxkl_avg&metrics=train/policy/clipfrac_avg&metrics=train/loss/policy_avg&metrics=train/loss/value_avg&metrics=train/val/clipfrac_avg&metrics=train/policy/entropy_avg&metrics=train/val/ratio&metrics=train/val/ratio_var&metrics=train/val/num_eos_tokens&metrics=train/lr&metrics=train/eps' \
"cleanrl/EleutherAI_pythia-1b-deduped__sft__tldr?tag=pr-1540" \
--env-ids models/minimal/ppo_tldr \
--pc.ncols 4 \
--pc.ncols-legend 1 \
--pc.xlabel "Episode" \
--output-filename benchmark/trl/pr-1540/ppo \
--scan-historyPPOTrainer
class trl.PPOTrainer
< 源码 >( args: PPOConfig processing_class: typing.Union[transformers.tokenization_utils_base.PreTrainedTokenizerBase, transformers.image_processing_utils.BaseImageProcessor, transformers.feature_extraction_utils.FeatureExtractionMixin, transformers.processing_utils.ProcessorMixin, NoneType] model: Module ref_model: typing.Optional[torch.nn.modules.module.Module] reward_model: Module train_dataset: Dataset value_model: Module data_collator: typing.Optional[transformers.data.data_collator.DataCollatorWithPadding] = None eval_dataset: typing.Union[datasets.arrow_dataset.Dataset, dict[str, datasets.arrow_dataset.Dataset], NoneType] = None optimizers: tuple = (None, None) callbacks: typing.Optional[list[transformers.trainer_callback.TrainerCallback]] = None peft_config: typing.Optional[ForwardRef('PeftConfig')] = None )
push_to_hub
< 源码 >( commit_message: typing.Optional[str] = 'End of training' blocking: bool = True token: typing.Optional[str] = None revision: typing.Optional[str] = None **kwargs )
参数
将 `self.model` 和 `self.processing_class` 上传到 🤗 模型中心的 `self.args.hub_model_id` 存储库。
PPOConfig
class trl.PPOConfig
< 源码 >( output_dir: typing.Optional[str] = None overwrite_output_dir: bool = False do_train: bool = False do_eval: bool = False do_predict: bool = False eval_strategy: typing.Union[transformers.trainer_utils.IntervalStrategy, str] = 'no' prediction_loss_only: bool = False per_device_train_batch_size: int = 8 per_device_eval_batch_size: int = 8 per_gpu_train_batch_size: typing.Optional[int] = None per_gpu_eval_batch_size: typing.Optional[int] = None gradient_accumulation_steps: int = 1 eval_accumulation_steps: typing.Optional[int] = None eval_delay: typing.Optional[float] = 0 torch_empty_cache_steps: typing.Optional[int] = None learning_rate: float = 5e-05 weight_decay: float = 0.0 adam_beta1: float = 0.9 adam_beta2: float = 0.999 adam_epsilon: float = 1e-08 max_grad_norm: float = 1.0 num_train_epochs: float = 3.0 max_steps: int = -1 lr_scheduler_type: typing.Union[transformers.trainer_utils.SchedulerType, str] = 'linear' lr_scheduler_kwargs: typing.Union[dict[str, typing.Any], str, NoneType] = <factory> warmup_ratio: float = 0.0 warmup_steps: int = 0 log_level: str = 'passive' log_level_replica: str = 'warning' log_on_each_node: bool = True logging_dir: typing.Optional[str] = None logging_strategy: typing.Union[transformers.trainer_utils.IntervalStrategy, str] = 'steps' logging_first_step: bool = False logging_steps: float = 10 logging_nan_inf_filter: bool = True save_strategy: typing.Union[transformers.trainer_utils.SaveStrategy, str] = 'steps' save_steps: float = 500 save_total_limit: typing.Optional[int] = None save_safetensors: typing.Optional[bool] = True save_on_each_node: bool = False save_only_model: bool = False restore_callback_states_from_checkpoint: bool = False no_cuda: bool = False use_cpu: bool = False use_mps_device: bool = False seed: int = 42 data_seed: typing.Optional[int] = None jit_mode_eval: bool = False use_ipex: bool = False bf16: typing.Optional[bool] = None fp16: bool = False fp16_opt_level: str = 'O1' half_precision_backend: str = 'auto' bf16_full_eval: bool = False fp16_full_eval: bool = False tf32: typing.Optional[bool] = None local_rank: int = -1 ddp_backend: typing.Optional[str] = None tpu_num_cores: typing.Optional[int] = None tpu_metrics_debug: bool = False debug: typing.Union[str, list[transformers.debug_utils.DebugOption]] = '' dataloader_drop_last: bool = False eval_steps: typing.Optional[float] = None dataloader_num_workers: int = 0 dataloader_prefetch_factor: typing.Optional[int] = None past_index: int = -1 run_name: typing.Optional[str] = None disable_tqdm: typing.Optional[bool] = None remove_unused_columns: typing.Optional[bool] = True label_names: typing.Optional[list[str]] = None load_best_model_at_end: typing.Optional[bool] = False metric_for_best_model: typing.Optional[str] = None greater_is_better: typing.Optional[bool] = None ignore_data_skip: bool = False fsdp: typing.Union[list[transformers.trainer_utils.FSDPOption], str, NoneType] = '' fsdp_min_num_params: int = 0 fsdp_config: typing.Union[dict[str, typing.Any], str, NoneType] = None fsdp_transformer_layer_cls_to_wrap: typing.Optional[str] = None accelerator_config: typing.Union[dict, str, NoneType] = None deepspeed: typing.Union[dict, str, NoneType] = None label_smoothing_factor: float = 0.0 optim: typing.Union[transformers.training_args.OptimizerNames, str] = 'adamw_torch' optim_args: typing.Optional[str] = None adafactor: bool = False group_by_length: bool = False length_column_name: typing.Optional[str] = 'length' report_to: typing.Union[NoneType, str, list[str]] = None ddp_find_unused_parameters: typing.Optional[bool] = None ddp_bucket_cap_mb: typing.Optional[int] = None ddp_broadcast_buffers: typing.Optional[bool] = None dataloader_pin_memory: bool = True dataloader_persistent_workers: bool = False skip_memory_metrics: bool = True use_legacy_prediction_loop: bool = False push_to_hub: bool = False resume_from_checkpoint: typing.Optional[str] = None hub_model_id: typing.Optional[str] = None hub_strategy: typing.Union[transformers.trainer_utils.HubStrategy, str] = 'every_save' hub_token: typing.Optional[str] = None hub_private_repo: typing.Optional[bool] = None hub_always_push: bool = False hub_revision: typing.Optional[str] = None gradient_checkpointing: bool = False gradient_checkpointing_kwargs: typing.Union[dict[str, typing.Any], str, NoneType] = None include_inputs_for_metrics: bool = False include_for_metrics: list = <factory> eval_do_concat_batches: bool = True fp16_backend: str = 'auto' push_to_hub_model_id: typing.Optional[str] = None push_to_hub_organization: typing.Optional[str] = None push_to_hub_token: typing.Optional[str] = None mp_parameters: str = '' auto_find_batch_size: bool = False full_determinism: bool = False torchdynamo: typing.Optional[str] = None ray_scope: typing.Optional[str] = 'last' ddp_timeout: int = 1800 torch_compile: bool = False torch_compile_backend: typing.Optional[str] = None torch_compile_mode: typing.Optional[str] = None include_tokens_per_second: typing.Optional[bool] = False include_num_input_tokens_seen: typing.Optional[bool] = False neftune_noise_alpha: typing.Optional[float] = None optim_target_modules: typing.Union[NoneType, str, list[str]] = None batch_eval_metrics: bool = False eval_on_start: bool = False use_liger_kernel: typing.Optional[bool] = False liger_kernel_config: typing.Optional[dict[str, bool]] = None eval_use_gather_object: typing.Optional[bool] = False average_tokens_across_devices: typing.Optional[bool] = True dataset_num_proc: typing.Optional[int] = None num_mini_batches: int = 1 total_episodes: typing.Optional[int] = None local_rollout_forward_batch_size: int = 64 num_sample_generations: int = 10 response_length: int = 53 stop_token: typing.Optional[typing.Literal['eos']] = None stop_token_id: typing.Optional[int] = None temperature: float = 0.7 missing_eos_penalty: typing.Optional[float] = None sft_model_path: str = 'EleutherAI/pythia-160m' world_size: typing.Optional[int] = None num_total_batches: typing.Optional[int] = None micro_batch_size: typing.Optional[int] = None local_batch_size: typing.Optional[int] = None batch_size: typing.Optional[int] = None local_mini_batch_size: typing.Optional[int] = None mini_batch_size: typing.Optional[int] = None exp_name: str = 'ppo_config' reward_model_path: str = 'EleutherAI/pythia-160m' model_adapter_name: typing.Optional[str] = None ref_adapter_name: typing.Optional[str] = None num_ppo_epochs: int = 4 whiten_rewards: bool = False kl_coef: float = 0.05 kl_estimator: typing.Literal['k1', 'k3'] = 'k1' cliprange: float = 0.2 vf_coef: float = 0.1 cliprange_value: float = 0.2 gamma: float = 1.0 lam: float = 0.95 ds3_gather_for_generation: bool = True )
参数
- exp_name (
str, 可选, 默认为os.path.basename(__file__)[ ---3])：此实验的名称。 - reward_model_path (
str, 可选, 默认为"EleutherAI/pythia-160m") — 奖励模型的路径。 - model_adapter_name (
str或None, 可选, 默认为None) — 当使用带有多个适配器的LoRA时，训练目标PEFT适配器的名称。 - ref_adapter_name (
str或None, 可选, 默认为None) — 当使用带有多个适配器的LoRA时，参考PEFT适配器的名称。 - num_ppo_epochs (
int, 可选, 默认为4) — 训练的轮数。 - whiten_rewards (
bool, 可选, 默认为False) — 是否白化奖励。 - kl_coef (
float, 可选, 默认为0.05) — KL系数。 - kl_estimator (
Literal["k1", "k3"], 可选, 默认为"k1") — 从近似KL散度中选择哪个KL散度估计器。默认为“k1”，这是一个直接的、无偏的估计器。可以设置为“k3”，这是一个方差更小的无偏估计器，似乎是“一个严格更好的估计器”。不能设置为“k2”，因为它用于日志记录。 - cliprange (
float, 可选, 默认为0.2) — 裁剪范围。 - vf_coef (
float, 可选, 默认为0.1) — 值函数系数。 - cliprange_value (
float, 可选, 默认为0.2) — 值函数的裁剪范围。 - gamma (
float, 可选, 默认为1.0) — 折扣因子。 - lam (
float, 可选, 默认为0.95) — GAE 的 Lambda 值。 - ds3_gather_for_generation (
bool, 可选, 默认为True) — 此设置适用于 DeepSpeed ZeRO-3。如果启用，策略模型权重将被收集用于生成，从而提高生成速度。但是，禁用此选项可以训练超过单个 GPU VRAM 容量的模型，尽管代价是生成速度较慢。
PPOTrainer 的配置类。
此类仅包含特定于 PPO 训练的参数。有关训练参数的完整列表，请参阅 TrainingArguments 和 OnPolicyConfig 文档。请注意，此类中的默认值可能与 TrainingArguments 中的默认值不同。
使用 HfArgumentParser，我们可以将此类别转换为可在命令行上指定的 argparse 参数。