[Liger-kernel] Add an option to use _apply_liger_kernel_to_instance() to load model

tests/e2e/run_qwen_gsm8k_model_rm_liger_kernel.sh

@@ -0,0 +1,52 @@
+set -x
+
+export VLLM_ATTENTION_BACKEND=XFORMERS
+
+python3 -m verl.trainer.main_ppo \
+    data.train_files=$HOME/data/gsm8k/train.parquet \
+    data.val_files=$HOME/data/gsm8k/test.parquet \
+    data.train_batch_size=1024 \
+    data.val_batch_size=1312 \
+    data.max_prompt_length=512 \
+    data.max_response_length=512 \
+    data.return_raw_chat=True \
+    actor_rollout_ref.model.path=Qwen/Qwen2.5-0.5B \
+    actor_rollout_ref.actor.optim.lr=1e-6 \
+    actor_rollout_ref.model.use_remove_padding=True \
+    +actor_rollout_ref.model.use_liger=True \
+    actor_rollout_ref.actor.optim.lr_warmup_steps_ratio=0.1 \
+    actor_rollout_ref.actor.ppo_mini_batch_size=256 \
+    actor_rollout_ref.actor.ppo_micro_batch_size=32 \
+    actor_rollout_ref.actor.fsdp_config.param_offload=False \
+    actor_rollout_ref.actor.fsdp_config.grad_offload=False \
+    actor_rollout_ref.actor.fsdp_config.optimizer_offload=False \
+    actor_rollout_ref.rollout.log_prob_micro_batch_size=128 \
+    actor_rollout_ref.rollout.tensor_model_parallel_size=2 \
+    actor_rollout_ref.rollout.name=vllm \
+    actor_rollout_ref.rollout.gpu_memory_utilization=0.4 \
+    actor_rollout_ref.ref.log_prob_micro_batch_size=128 \
+    actor_rollout_ref.ref.fsdp_config.param_offload=True \
+    critic.optim.lr=1e-5 \
+    critic.model.use_remove_padding=True \
+    critic.optim.lr_warmup_steps_ratio=0.05 \
+    critic.model.path=Qwen/Qwen2.5-0.5B \
+    critic.model.enable_gradient_checkpointing=False \
+    critic.ppo_micro_batch_size=32 \
+    critic.model.fsdp_config.param_offload=False \
+    critic.model.fsdp_config.grad_offload=False \
+    critic.model.fsdp_config.optimizer_offload=False \
+    reward_model.enable=True \
+    reward_model.model.path=Qwen/Qwen2.5-0.5B\
+    reward_model.model.use_remove_padding=True \
+    reward_model.model.fsdp_config.param_offload=True \
+    reward_model.micro_batch_size=16 \
+    algorithm.kl_ctrl.kl_coef=0.001 \
+    trainer.critic_warmup=0 \
+    trainer.logger=['console'] \
+    +trainer.val_before_train=False \
+    trainer.project_name='verl_example' \
+    trainer.experiment_name='Qwen2.5-0.5B-ci_hybrid_rm' \
+    trainer.n_gpus_per_node=8 \
+    trainer.nnodes=1 \
+    trainer.save_freq=-1 \
+    trainer.total_training_steps=1 $@

verl/workers/fsdp_workers.py

@@ -140,6 +140,7 @@ def _build_model_optimizer(self,
                                use_remove_padding=False,
                                enable_gradient_checkpointing=False,
                                trust_remote_code=False,
+                               use_liger=False,
                                role='actor'):
         from verl.utils.model import print_model_size, update_model_config
         from verl.utils.torch_dtypes import PrecisionType
@@ -193,6 +194,17 @@ def _build_model_optimizer(self,
                                                                 config=actor_model_config,
                                                                 attn_implementation='flash_attention_2',
                                                                 trust_remote_code=trust_remote_code)
+            # Apply Liger kernel to the model if use_liger is set to True
+            if use_liger:
+                try:
+                    # Import Liger kernel module and use it to load the model
+                    from liger_kernel.transformers.monkey_patch import _apply_liger_kernel_to_instance
+                    _apply_liger_kernel_to_instance(model=actor_module)
+                except ImportError:
+                    # Fallback to use AutoModelForCausalLM and print warning message
+                    logger.warning("Liger kernel was requested but not installed - falling back to AutoModelForCausalLM")
+                    logger.warning("To enable Liger kernel, install it with: pip install liger-kernel")
+
             # some parameters may not in torch_dtype. TODO(zhangchi.usc1992) remove this after we switch to fsdp2
             actor_module.to(torch_dtype)
 
@@ -333,6 +345,7 @@ def init_model(self):
                 use_remove_padding=use_remove_padding,
                 enable_gradient_checkpointing=self.config.model.get('enable_gradient_checkpointing', False),
                 trust_remote_code=self.config.model.get('trust_remote_code', False),
+                use_liger=self.config.model.get('use_liger', False),
                 role='actor')
 
             # get the original unwrapped module
@@ -365,6 +378,7 @@ def init_model(self):
                                                                use_remove_padding=use_remove_padding,
                                                                trust_remote_code=self.config.model.get(
                                                                    'trust_remote_code', False),
+                                                               use_liger=self.config.model.get('use_liger', False),
                                                                role='ref')[0]
             OmegaConf.set_struct(self.config.ref, True)
             with open_dict(self.config.ref):