Refactor and clean up hf_ptq.py

This script has several separate logic and the code of them are
entangled, making it really hard to add new features

Refactor them so that we separate these logics:

1. sparsity, all logic go to sparsity_main. TODO: we may actually move this
   logic out to a separate script

2. quantize, all logic go to quantize_main.

   2.1 plain quantization with a single quantization format

   2.2 auto quantization

In the quantization pipeline, separate the pipeline to:

1. model loading
2. calibrate dataset loading
3. pre-quantize processing
4. actual quantize
5. post-quantize processing
6. quantized model export

Signed-off-by: Shengliang Xu <[email protected]>

Author: shengliangxu

examples/llm_ptq/example_utils.py

@@ -20,20 +20,27 @@
 import sys
 import warnings
 from pathlib import Path
+from typing import Any
 
 import torch
 import transformers
 from accelerate import infer_auto_device_map, init_empty_weights
 from accelerate.utils import get_max_memory
-from transformers import AutoConfig, AutoModelForCausalLM, AutoProcessor, AutoTokenizer
+from transformers import (
+    AutoConfig,
+    AutoModelForCausalLM,
+    AutoProcessor,
+    AutoTokenizer,
+    ProcessorMixin,
+)
 
 try:
     from huggingface_hub import snapshot_download
 except ImportError:
     snapshot_download = None
 
 import modelopt.torch.quantization as mtq
-from modelopt.torch.utils.image_processor import MllamaImageProcessor
+from modelopt.torch.utils.image_processor import BaseImageProcessor, MllamaImageProcessor
 
 SPECULATIVE_MODEL_LIST = ["Eagle", "Medusa"]
 
@@ -127,52 +134,50 @@ def build_quant_cfg(
     qformat,
     kv_cache_qformat,
     awq_block_size,
-    auto_quantize,
     model_type,
     quant_cfg_choices,
     kv_quant_cfg_choices,
-):
+) -> dict[str, Any]:
     quant_cfg = {}
-    if not auto_quantize:
-        assert qformat in quant_cfg_choices, (
-            f"Unsupported quantization format: {qformat} with {kv_cache_qformat} KV cache"
-        )
+    assert qformat in quant_cfg_choices, (
+        f"Unsupported quantization format: {qformat} with {kv_cache_qformat} KV cache"
+    )
 
-        quant_cfg = quant_cfg_choices[qformat]
-
-        if "awq" in qformat:
-            quant_cfg = copy.deepcopy(quant_cfg_choices[qformat])
-            weight_quantizer = quant_cfg["quant_cfg"]["*weight_quantizer"]
-            if isinstance(weight_quantizer, list):
-                weight_quantizer = weight_quantizer[0]
-            # If awq_block_size argument is provided, update weight_quantizer
-            if awq_block_size:
-                weight_quantizer["block_sizes"][-1] = awq_block_size
-
-            # Coarser optimal scale search seems to resolve the overflow in TRT-LLM for some models
-            if qformat == "w4a8_awq" and model_type in ["gemma", "mpt"]:
-                quant_cfg["algorithm"] = {"method": "awq_lite", "alpha_step": 1}
-
-        enable_quant_kv_cache = kv_cache_qformat != "none"
-        print(f"{'Enable' if enable_quant_kv_cache else 'Disable'} KV cache quantization")
-
-        # Check if any bmm_quantizer is in the quant_cfg. If so, we need to enable the bmm_quantizer.
-        if enable_quant_kv_cache:
-            quant_cfg = mtq.update_quant_cfg_with_kv_cache_quant(
-                quant_cfg,
-                getattr(mtq, kv_quant_cfg_choices[kv_cache_qformat])["quant_cfg"],
-            )
+    quant_cfg = quant_cfg_choices[qformat]
+
+    if "awq" in qformat:
+        quant_cfg = copy.deepcopy(quant_cfg_choices[qformat])
+        weight_quantizer = quant_cfg["quant_cfg"]["*weight_quantizer"]
+        if isinstance(weight_quantizer, list):
+            weight_quantizer = weight_quantizer[0]
+        # If awq_block_size argument is provided, update weight_quantizer
+        if awq_block_size:
+            weight_quantizer["block_sizes"][-1] = awq_block_size
+
+        # Coarser optimal scale search seems to resolve the overflow in TRT-LLM for some models
+        if qformat == "w4a8_awq" and model_type in ["gemma", "mpt"]:
+            quant_cfg["algorithm"] = {"method": "awq_lite", "alpha_step": 1}
+
+    enable_quant_kv_cache = kv_cache_qformat != "none"
+    print(f"{'Enable' if enable_quant_kv_cache else 'Disable'} KV cache quantization")
+
+    # Check if any bmm_quantizer is in the quant_cfg. If so, we need to enable the bmm_quantizer.
+    if enable_quant_kv_cache:
+        quant_cfg = mtq.update_quant_cfg_with_kv_cache_quant(
+            quant_cfg,
+            getattr(mtq, kv_quant_cfg_choices[kv_cache_qformat])["quant_cfg"],
+        )
 
-        # Gemma 7B has accuracy regression using alpha 1. We set 0.5 instead.
-        if model_type == "gemma" and "int8_sq" in qformat:
-            quant_cfg["algorithm"] = {"method": "smoothquant", "alpha": 0.5}
+    # Gemma 7B has accuracy regression using alpha 1. We set 0.5 instead.
+    if model_type == "gemma" and "int8_sq" in qformat:
+        quant_cfg["algorithm"] = {"method": "smoothquant", "alpha": 0.5}
 
-        if model_type == "phi4mm":
-            # Only quantize the language model
-            quant_cfg["quant_cfg"]["*speech*"] = {"enable": False}
-            quant_cfg["quant_cfg"]["*audio*"] = {"enable": False}
-            quant_cfg["quant_cfg"]["*image*"] = {"enable": False}
-            quant_cfg["quant_cfg"]["*vision*"] = {"enable": False}
+    if model_type == "phi4mm":
+        # Only quantize the language model
+        quant_cfg["quant_cfg"]["*speech*"] = {"enable": False}
+        quant_cfg["quant_cfg"]["*audio*"] = {"enable": False}
+        quant_cfg["quant_cfg"]["*image*"] = {"enable": False}
+        quant_cfg["quant_cfg"]["*vision*"] = {"enable": False}
 
     return quant_cfg
 
@@ -205,8 +210,8 @@ def get_tokenizer(ckpt_path, trust_remote_code=False, **kwargs):
 
 
 def get_processor(
-    ckpt_path, model_type, device=None, trust_remote_code=False, attn_implementation=None
-):
+    ckpt_path, model_type, device: str = "auto", trust_remote_code=False, attn_implementation=None
+) -> BaseImageProcessor | ProcessorMixin | None:
     """
     Returns a :class:`modelopt.torch.utils.image_processor.MllamaImageProcessor` object.
     """
@@ -241,6 +246,8 @@ def get_processor(
 
         return MllamaImageProcessor(processor, device)
 
+    return None
+
 
 def get_dtype(dtype):
     if dtype == "bf16":