unsloth/scripts/benchmarks/make_lora_adapter.py
Daniel Han d118195c8b Add Phase 0+1 GRPO backend comparison scaffolding
Phase 0 (canonical reference):
- scripts/benchmarks/qwen3_grpo_notebook.py: notebook-to-script port of
  Qwen3_(4B)-GRPO.ipynb with StatisticsCallback from torch_debugging_utils
  and equivalence-friendly sampling (temp=0.1, top_p=0.97, min_p=0.5, top_k=5).
- scripts/benchmarks/results/notebook_ref_10.md: 10-step reference run table
  (median step post-warmup = 5.80s, peak 158.9 GB).
- scripts/benchmarks/results/stats/notebook_ref_10.json: full per-step logs
  for downstream compare_training_runs checks.

Phase 1 (rollout-only LoRA comparison scaffold):
- scripts/benchmarks/make_lora_adapter.py: one-shot that materializes a
  rank-32 LoRA at outputs/lora_rank32_fresh. Re-initializes lora_B with a
  tiny gaussian so the adapter isn't a no-op (otherwise LoRA kernels can
  short-circuit and we'd be measuring the base model).
- scripts/benchmarks/cb_vs_vllm_generation.py: extended with --lora_adapter
  for vLLM (LoRARequest) and tpaged (peft.PeftModel.from_pretrained,
  no merge_adapter), plus a new unsloth_fi_false backend that exercises the
  custom HF inference path (cached fp16 LoRA via fast_linear_forward).
  Sampling knobs are exposed and default to equivalence params.

Phase 2 scaffold:
- scripts/benchmarks/qwen3_grpo_unified.py: single entry point for all 5
  backends (vllm, unsloth_fi_false, cb_paged, cb_sdpa, naive_trl) sharing
  dataset, reward funcs, sampling, and StatisticsCallback. Skips the first
  3 steps when reporting median step wall.

No unsloth internals touched.
2026-04-20 13:54:06 +00:00

93 lines
3.3 KiB
Python

"""One-shot: materialize a rank-32 LoRA adapter on `unsloth/Qwen3-4B-Base`.
Writes a PEFT-style directory so every backend (vLLM `LoRARequest`,
`peft.PeftModel.from_pretrained`, Unsloth `FastLanguageModel.get_peft_model`)
can load the SAME weights. Random-init is fine for throughput measurement --
the goal is to have LoRA kernels active during generation, not a trained
model.
Run:
CUDA_VISIBLE_DEVICES=6 python scripts/benchmarks/make_lora_adapter.py \
--output outputs/lora_rank32_fresh
"""
from __future__ import annotations
import argparse
import os
from pathlib import Path
def parse_args():
p = argparse.ArgumentParser()
p.add_argument("--model_name", default="unsloth/Qwen3-4B-Base")
p.add_argument("--output", default="outputs/lora_rank32_fresh")
p.add_argument("--rank", type=int, default=32)
return p.parse_args()
def main():
args = parse_args()
out_dir = Path(args.output).resolve()
out_dir.mkdir(parents=True, exist_ok=True)
# Use vanilla HF -- PEFT's save_pretrained yields the canonical
# adapter_config.json + adapter_model.safetensors that vLLM's LoRARequest
# expects. Loading via Unsloth would leak Unsloth-specific LoRA wrappers.
import torch
from transformers import AutoModelForCausalLM, AutoTokenizer
from peft import LoraConfig, get_peft_model
tok = AutoTokenizer.from_pretrained(args.model_name)
if tok.pad_token is None:
tok.pad_token = tok.eos_token
# bf16 base; we only need structure + save. Keep on CPU to avoid a GPU load
# just for `save_pretrained`.
print(f"[make_lora_adapter] Loading {args.model_name} on CPU...")
model = AutoModelForCausalLM.from_pretrained(args.model_name, dtype=torch.bfloat16)
peft_cfg = LoraConfig(
r=args.rank,
lora_alpha=args.rank * 2,
target_modules=["q_proj", "k_proj", "v_proj", "o_proj",
"gate_proj", "up_proj", "down_proj"],
bias="none",
task_type="CAUSAL_LM",
lora_dropout=0.0,
)
peft_model = get_peft_model(model, peft_cfg)
peft_model.print_trainable_parameters()
# Ensure both A and B matrices are non-zero. PEFT initializes A with
# kaiming_uniform and B with zeros -- which makes the adapter a no-op and
# would mask LoRA kernels on some backends. Seed B with tiny random values.
n_reinit = 0
with torch.no_grad():
for name, p in peft_model.named_parameters():
if "lora_B" in name:
p.normal_(mean=0.0, std=1e-4)
n_reinit += 1
print(f"[make_lora_adapter] Reinitialized {n_reinit} lora_B matrices with tiny gaussian.")
peft_model.save_pretrained(str(out_dir))
tok.save_pretrained(str(out_dir))
# Sanity: verify safetensors file present and non-trivial.
from safetensors import safe_open
st_path = out_dir / "adapter_model.safetensors"
n_zero_tensors = 0
n_tensors = 0
with safe_open(str(st_path), framework="pt") as f:
for key in f.keys():
t = f.get_tensor(key)
n_tensors += 1
if (t == 0).all().item():
n_zero_tensors += 1
print(f"[make_lora_adapter] Wrote {n_tensors} tensors to {st_path} "
f"({n_zero_tensors} all-zero).")
print(f"[make_lora_adapter] Adapter saved to {out_dir}")
if __name__ == "__main__":
main()