""" Instruction-tuning on the Alpaca dataset using a regular finetuning procedure (updating all layers). Note: If you run into a CUDA error "Expected is_sm80 to be true, but got false", uncomment the line `torch.backends.cuda.enable_flash_sdp(False)` in the script below (see https://github.com/Lightning-AI/lit-llama/issues/101). """ import os import time from functools import partial import lightning as L from lightning.fabric.strategies import FSDPStrategy import numpy as np import torch from torch.distributed.fsdp.wrap import transformer_auto_wrap_policy from generate import generate from lit_llama.model import Block, LLaMA, LLaMAConfig from lit_llama.tokenizer import Tokenizer from lit_llama.utils import save_model_checkpoint from scripts.prepare_alpaca import generate_prompt eval_interval = 1000 save_interval = 1000 eval_iters = 100 log_interval = 100 devices = 4 # Hyperparameters learning_rate = 3e-5 batch_size = 128 / devices micro_batch_size = 4 gradient_accumulation_steps = batch_size // micro_batch_size epoch_size = 50000 # train dataset size num_epochs = 5 max_iters = num_epochs * epoch_size // micro_batch_size // devices weight_decay = 0.0 block_size = 512 warmup_steps = 100 def main( data_dir: str = "data/alpaca", pretrained_path: str = "checkpoints/lit-llama/7B/lit-llama.pth", out_dir: str = "out/full/alpaca", ): auto_wrap_policy = partial(transformer_auto_wrap_policy, transformer_layer_cls={Block}) strategy = FSDPStrategy(auto_wrap_policy=auto_wrap_policy, activation_checkpointing=Block) fabric = L.Fabric(accelerator="cuda", devices=devices, precision="bf16-mixed", strategy=strategy) fabric.launch() fabric.seed_everything(1337 + fabric.global_rank) if fabric.global_rank == 0: os.makedirs(out_dir, exist_ok=True) train_data, val_data = load_datasets(data_dir=data_dir) config = LLaMAConfig.from_name("7B") config.block_size = block_size checkpoint = torch.load(pretrained_path) with fabric.device: torch.set_default_tensor_type(torch.HalfTensor) model = LLaMA(config).bfloat16() torch.set_default_tensor_type(torch.FloatTensor) model.load_state_dict(checkpoint, strict=False) model = fabric.setup_module(model) optimizer = torch.optim.AdamW(model.parameters(), lr=learning_rate) optimizer = fabric.setup_optimizers(optimizer) train(fabric, model, optimizer, train_data, val_data, out_dir) # Save the final checkpoint at the end of training save_model_checkpoint(fabric, model, os.path.join(out_dir, "lit-llama-full-finetuned.pth")) def train( fabric: L.Fabric, model: torch.nn.Module, optimizer: torch.optim.Optimizer, train_data: np.ndarray, val_data: np.ndarray, out_dir: str, ) -> None: """The training loop. Loosely based on the nanoGPT implementation: https://github.com/karpathy/nanoGPT. """ step_count = 0 model.train() for iter_num in range(max_iters): is_accumulating = (iter_num + 1) % gradient_accumulation_steps == 0 if step_count <= warmup_steps: # linear warmup lr = learning_rate * step_count / warmup_steps for param_group in optimizer.param_groups: param_group['lr'] = lr t0 = time.time() with fabric.no_backward_sync(model, enabled=is_accumulating): input_ids, targets = get_batch(fabric, train_data) logits = model(input_ids) loss = loss_fn(logits, targets) fabric.backward(loss) if not is_accumulating: optimizer.step() optimizer.zero_grad() step_count += 1 if step_count % eval_interval == 0: val_loss = validate(fabric, model, val_data) fabric.print(f"step {iter_num}: val loss {val_loss:.4f}") fabric.barrier() if step_count % save_interval == 0: print(f"Saving weights to {out_dir}") save_model_checkpoint(fabric, model, os.path.join(out_dir, f"iter-{iter_num:06d}-ckpt.pth")) dt = time.time() - t0 if iter_num % log_interval == 0: fabric.print(f"iter {iter_num}: loss {loss.item():.4f}, time: {dt*1000:.2f}ms") def generate_response(model, instruction): tokenizer = Tokenizer("checkpoints/lit-llama/tokenizer.model") sample = {"instruction": instruction, "input": ""} prompt = generate_prompt(sample) encoded = tokenizer.encode(prompt, bos=True, eos=False, device=model.device) output = generate( model, idx=encoded, max_seq_length=block_size, max_new_tokens=100, ) output = tokenizer.decode(output) return output # output.split("### Response:")[1].strip() @torch.no_grad() def validate(fabric: L.Fabric, model: torch.nn.Module, val_data: np.ndarray) -> torch.Tensor: fabric.print("Validating ...") model.eval() losses = torch.zeros(eval_iters) for k in range(eval_iters): input_ids, targets = get_batch(fabric, val_data) logits = model(input_ids) loss = loss_fn(logits, targets) losses[k] = loss.item() out = losses.mean() # produce an example: instruction = "Recommend a movie for me to watch during the weekend and explain the reason." output = generate_response(model, instruction) fabric.print(instruction) fabric.print(output) model.train() return out.item() def loss_fn(logits, targets): # shift the targets such that output n predicts token n+1 logits = logits[..., :-1, :].contiguous() targets = targets[..., 1:].contiguous() loss = torch.nn.functional.cross_entropy(logits.view(-1, logits.size(-1)), targets.view(-1), ignore_index=-1) return loss def get_batch(fabric: L.Fabric, data: list): ix = torch.randint(len(data), (micro_batch_size,)) input_ids = [data[i]["input_ids"].type(torch.int64) for i in ix] labels = [data[i]["labels"].type(torch.int64) for i in ix] max_len = max(len(s) for s in input_ids) def pad_right(x, pad_id): # pad right based on the longest sequence n = max_len - len(x) return torch.cat((x, torch.full((n,), pad_id, dtype=x.dtype))) x = torch.stack([pad_right(x, pad_id=0) for x in input_ids]) y = torch.stack([pad_right(x, pad_id=-1) for x in labels]) x, y = fabric.to_device((x.pin_memory(), y.pin_memory())) return x, y def load_datasets(data_dir): train_data = torch.load(os.path.join(data_dir, "train.pt")) val_data = torch.load(os.path.join(data_dir, "test.pt")) return train_data, val_data if __name__ == "__main__": # Uncomment this line if you see an error: "Expected is_sm80 to be true, but got false" # torch.backends.cuda.enable_flash_sdp(False) torch.set_float32_matmul_precision("high") from jsonargparse.cli import CLI CLI(main)