PTQ via NeMo-Run CLI (#10984)

* PTQ support in nemo CLI

Signed-off-by: Jan Lasek <janek.lasek@gmail.com>

* Naming engine vs checkpoint

Signed-off-by: Jan Lasek <janek.lasek@gmail.com>

---------

Signed-off-by: Jan Lasek <janek.lasek@gmail.com>

nemo/collections/llm/__init__.py

@@ -214,7 +214,7 @@
 try:
     import nemo_run as run
 
-    from nemo.collections.llm.api import export_ckpt, finetune, generate, import_ckpt, pretrain, train, validate
+    from nemo.collections.llm.api import export_ckpt, finetune, generate, import_ckpt, pretrain, ptq, train, validate
     from nemo.collections.llm.recipes import *  # noqa
 
     __all__.extend(
@@ -226,6 +226,7 @@
             "validate",
             "finetune",
             "generate",
+            "ptq",
         ]
     )
 except ImportError as error:

nemo/collections/llm/api.py

@@ -24,6 +24,7 @@
 from typing_extensions import Annotated
 
 import nemo.lightning as nl
+from nemo.collections.llm.quantization import ExportConfig, QuantizationConfig
 from nemo.lightning import (
     AutoResume,
     NeMoLogger,
@@ -67,7 +68,8 @@ def train(
         resume (Optional[Union[AutoResume, Resume]]): Resume training from a checkpoint.
         optim (Optional[OptimizerModule]): The optimizer module to be used. If not provided, the default optimizer
             from the model will be used.
-        tokenizer (Optional[TokenizerType]): Tokenizer setting to be applied. Can be 'data' or 'model' or an instance of TokenizerSpec.
+        tokenizer (Optional[TokenizerType]): Tokenizer setting to be applied. Can be 'data' or 'model'
+            or an instance of TokenizerSpec.
         export (Optional[str]): Filename to save the exported checkpoint after training.
         model_transform (Optional[Union[Callable[[nn.Module], nn.Module], PEFT]]): A model transform to be applied.
 
@@ -83,7 +85,7 @@ def train(
         >>> data = llm.SquadDataModule(seq_length=4096, global_batch_size=16, micro_batch_size=2)
         >>> precision = nl.MegatronMixedPrecision(precision="bf16-mixed")
         >>> trainer = nl.Trainer(strategy=nl.MegatronStrategy(tensor_model_parallel_size=2), plugins=precision)
-        >>> train(model, data, trainer, tokenizer="data")
+        >>> llm.train(model, data, trainer, tokenizer="data")
         PosixPath('/path/to/log_dir')
     """
     app_state = _setup(
@@ -185,7 +187,7 @@ def finetune(
         >>> data = llm.SquadDataModule(seq_length=4096, global_batch_size=16, micro_batch_size=2)
         >>> precision = nl.MegatronMixedPrecision(precision="bf16-mixed")
         >>> trainer = nl.Trainer(strategy=nl.MegatronStrategy(tensor_model_parallel_size=2), plugins=precision)
-        >>> finetune(model, data, trainer, peft=llm.peft.LoRA()])
+        >>> llm.finetune(model, data, trainer, peft=llm.peft.LoRA()])
         PosixPath('/path/to/log_dir')
     """
 
@@ -223,7 +225,8 @@ def validate(
         resume (Optional[AutoResume]): Resume from a checkpoint for validation.
         optim (Optional[OptimizerModule]): The optimizer module to be used. If not provided, the default optimizer
             from the model will be used.
-        tokenizer (Optional[TokenizerType]): Tokenizer setting to be applied. Can be 'data' or 'model' or an instance of TokenizerSpec.
+        tokenizer (Optional[TokenizerType]): Tokenizer setting to be applied. Can be 'data' or 'model'
+            or an instance of TokenizerSpec.
         model_transform (Optional[Union[Callable[[nn.Module], nn.Module], PEFT]]): A model transform to be applied.
 
     Returns:
@@ -236,7 +239,7 @@ def validate(
         >>> data = llm.SquadDataModule(seq_length=4096, global_batch_size=16, micro_batch_size=2)
         >>> precision = nl.MegatronMixedPrecision(precision="bf16-mixed")
         >>> trainer = nl.Trainer(strategy=nl.MegatronStrategy(tensor_model_parallel_size=2), plugins=precision)
-        >>> validate(model, data, trainer, tokenizer="data")
+        >>> llm.validate(model, data, trainer, tokenizer="data")
         PosixPath('/path/to/log_dir')
     """
     app_state = _setup(
@@ -255,6 +258,60 @@ def validate(
     return app_state.exp_dir
 
 
+@run.cli.entrypoint(name="ptq", namespace="llm")
+def ptq(
+    nemo_checkpoint: str,
+    calib_tp: int = 1,
+    calib_pp: int = 1,
+    quantization_config: Annotated[Optional[QuantizationConfig], run.Config[QuantizationConfig]] = None,
+    export_config: Optional[Union[ExportConfig, run.Config[ExportConfig]]] = None,
+) -> Path:
+    # TODO: Fix "nemo_run.cli.cli_parser.CLIException: An unexpected error occurred (Argument: , Context: {})"
+    """
+    Applies Post-Training Quantization (PTQ) for a model using the specified quantization and export configs. It runs
+    calibration for a small dataset to collect scaling factors low-precision GEMMs used by desired quantization method.
+    This function produces TensorRT-LLM checkpoint ready for deployment using nemo.export and nemo.deploy modules
+    or direcly using TensorRT-LLM library.
+    The function can be used through the NeMo CLI in the following way:
+    ```bash
+    # Run calibration using tensor parallel set to 8 and export quantized checkpoint with tensor parallel equal 2
+    nemo llm ptq nemo_checkpoint=/models/Llama-3-70B \
+        export_config.path=/models/Llama-3-70B-FP8 \
+        calib_tp=8 \
+        export_config.inference_tensor_parallel=2
+    # Choose different quantization method, for example, INT8 SmoothQuant
+    nemo llm ptq nemo_checkpoint=/models/Llama-3-8B \
+        export_config.path=/models/Llama-3-8B-INT8_SQ \
+        quantization_config.algorithm=int8_sq
+    ```
+    Args:
+        nemo_checkpoint (str): The path to model to be quantized.
+        calib_tp (int): Calibration tensor parallelism.
+        calib_pp (int): Calibration pipeline parallelism.
+        quantization_config (QuantizationConfig): Configuration for quantization algorithm.
+        export_config (ExportConfig): Export configuration for TensorRT-LLM checkpoint.
+    Returns:
+        Path: The path where the quantized checkpoint has been saved after calibration.
+    """
+    if export_config.path is None:
+        raise ValueError("The export_config.path needs to be specified, got None.")
+
+    from nemo.collections.llm import quantization
+
+    quantizer = quantization.Quantizer(quantization_config, export_config)
+
+    model = quantization.load_with_modelopt_layer_spec(nemo_checkpoint, calib_tp, calib_pp)
+
+    model = quantizer.quantize(model)
+
+    quantizer.export(model, nemo_checkpoint)
+
+    console = Console()
+    console.print(f"[green]✓ PTQ succeded, quantized checkpoint exported to {export_config.path}[/green]")
+
+    return export_config.path
+
+
 @run.cli.entrypoint(namespace="llm")
 def deploy(
     nemo_checkpoint: Path = None,

nemo/collections/llm/quantization/quantizer.py

@@ -15,6 +15,7 @@
 import os
 import shutil
 from dataclasses import dataclass
+from pathlib import Path
 from typing import Optional, Union
 
 import torch
@@ -75,17 +76,20 @@ class QuantizationConfig:
 
 @dataclass
 class ExportConfig:
-    """Inference configuration for the quantized TensorRT-LLM engine"""
+    """Inference configuration for the quantized TensorRT-LLM checkpoint."""
 
-    path: str
+    path: Union[Path, str]
     dtype: Union[str, int] = "bf16"
     decoder_type: Optional[str] = None
     inference_tensor_parallel: int = 1
     inference_pipeline_parallel: int = 1
 
+    def __post_init__(self):
+        self.path = Path(self.path)
+
 
 def get_modelopt_decoder_type(config: llm.GPTConfig) -> str:
-    """Infers the modelopt decoder type from GPTConfig class"""
+    """Infers the modelopt decoder type from GPTConfig class."""
     mapping = [
         (llm.Baichuan2Config, "baichuan"),
         (llm.ChatGLMConfig, "chatglm"),
@@ -109,17 +113,17 @@ def get_modelopt_decoder_type(config: llm.GPTConfig) -> str:
 
 
 class Quantizer:
-    """Post-training quantization (PTQ) and TRT-LLM export of NeMo 2.0 checkpoints.
+    """Post-training quantization (PTQ) and TensorRT-LLM export of NeMo 2.0 checkpoints.
 
     PTQ converts selected model layers to low-precision format (e.g., INT4, FP8) for efficient serving.
     The process consist of several steps:
 
         1. Loading a Nemo model from disk using appropriate parallelism strategy
         2. Calibrating the model to obtain appropriate algorithm-specific scaling factors
-        3. Producing output directory
+        3. Producing an output directory with a quantized checkpoint and a tokenizer
 
     The output directory produced is intended to be consumed by TensorRT-LLM toolbox
-    for efficient inference. This can be achieved using NeMo inference containers.
+    for efficient inference. This can be achieved using nemo.export.tensorrt_llm module.
     """
 
     def __init__(self, quantization_config: QuantizationConfig, export_config: ExportConfig):
@@ -231,6 +235,7 @@ def quantize(self, model: llm.GPTModel, forward_loop=None):
     def create_megatron_forward_loop(
         self, get_dataloader, num_batches, seq_length=None, micro_batch_size=None, decoder_seq_length=None
     ):
+        """Create a forward loop for over a given data iterator."""
         from megatron.core.pipeline_parallel.schedules import get_forward_backward_func
 
         forward_backward_func = get_forward_backward_func()
@@ -262,6 +267,7 @@ def loop(model):
         return loop
 
     def export(self, model: llm.GPTModel, model_dir: str) -> None:
+        """Export model to a TensorRT-LLM checkpoint."""
         assert self.export_config is not None, "Export config is not set"
         # TODO: Add sample generate
         # TODO: Support megatron_amp_O2
@@ -294,7 +300,7 @@ def export(self, model: llm.GPTModel, model_dir: str) -> None:
 def get_calib_data_iter(
     data: str = "cnn_dailymail", batch_size: int = 64, calib_size: int = 512, max_sequence_length: int = 512
 ):
-    """Creates a sample data iterator for calibration"""
+    """Creates a sample data iterator for calibration."""
     if data == "wikitext":
         dataset = load_dataset("wikitext", "wikitext-103-v1", split="train")
         text_column = "text"
@@ -314,6 +320,8 @@ def get_calib_data_iter(
 
 
 def create_data_iterator_getter(model, dataset, seq_len, batch_size, calibration_size):
+    """Create a function that provides iterator over a given dataset."""
+
     def _iterator():
         CHARACTERS_PER_TOKEN = 4