[TeaCache]: Add Coefficient Estimation (#940)

Signed-off-by: princepride <wangzhipeng628@gmail.com>
Signed-off-by: 汪志鹏 <wangzhipeng628@gmail.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>
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汪志鹏andHongsheng Liu authored and GitHub committed 2026-01-31 22:06:17 +13:00
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@@ -204,7 +204,151 @@ Key point for writing the example:
+ Save or display the generated results so users can validate the integration.
## Step 5: Open a Pull Request
## Step 5: TeaCache Coefficient Estimation (Optional)
If your model supports TeaCache acceleration, you need to estimate the polynomial coefficients for optimal caching performance.
### 5.1 Add Extractor Function
First, implement an extractor function in `vllm_omni/diffusion/cache/teacache/extractors.py`. The extractor extracts the modulated input and defines how to run transformer blocks:
```python
def extract_your_model_context(
module: nn.Module,
hidden_states: torch.Tensor,
timestep: torch.Tensor,
**kwargs: Any,
) -> CacheContext:
# 1. Preprocessing
temb = module.time_embed(timestep)
# 2. Extract modulated input (for cache decision)
modulated_input = module.transformer_blocks[0].norm1(hidden_states, temb)
# 3. Define transformer execution
def run_transformer_blocks():
h = hidden_states
for block in module.transformer_blocks:
h = block(h, temb=temb)
return (h,)
# 4. Define postprocessing
def postprocess(h):
return module.proj_out(module.norm_out(h, temb))
return CacheContext(
modulated_input=modulated_input,
hidden_states=hidden_states,
encoder_hidden_states=None,
temb=temb,
run_transformer_blocks=run_transformer_blocks,
postprocess=postprocess,
)
```
Register it in `EXTRACTOR_REGISTRY`:
```python
EXTRACTOR_REGISTRY = {
...
"YourTransformer2DModel": extract_your_model_context,
}
```
### 5.2 Add Adapter for Coefficient Estimation
Add an adapter in `vllm_omni/diffusion/cache/teacache/coefficient_estimator.py`:
```python
class YourModelAdapter:
@staticmethod
def load_pipeline(model_path: str, device: str, dtype: torch.dtype) -> Any:
# Load your pipeline
...
@staticmethod
def get_transformer(pipeline: Any) -> tuple[Any, str]:
return pipeline.transformer, "YourTransformer2DModel"
@staticmethod
def install_hook(transformer: Any, hook: DataCollectionHook) -> None:
registry = HookRegistry.get_or_create(transformer)
registry.register_hook(hook._HOOK_NAME, hook)
_MODEL_ADAPTERS["YourModel"] = YourModelAdapter
```
### 5.3 Run Coefficient Estimation
Use the provided script to estimate coefficients:
```python
from vllm_omni.diffusion.cache.teacache.coefficient_estimator import (
TeaCacheCoefficientEstimator,
)
from datasets import load_dataset
from tqdm import tqdm
# Load model
estimator = TeaCacheCoefficientEstimator(
model_path="/path/to/model",
model_type="Bagel", # Your model type
device="cuda",
)
# Load prompts (paper suggests ~70 prompts)
dataset = load_dataset("nateraw/parti-prompts", split="train")
prompts = dataset["Prompt"][:70]
# Collect data
for prompt in tqdm(prompts):
estimator.collect_from_prompt(prompt, num_inference_steps=50)
# Estimate coefficients
coeffs = estimator.estimate(poly_order=4)
print(f"Coefficients: {coeffs}")
```
### 5.4 Interpreting Coefficient Estimation Results
The estimator outputs statistics and polynomial coefficients. Here's how to interpret them:
**Example Output:**
```
Data statistics:
Count: 48
Input Diffs (x): min=1.1089e-02, max=5.2555e-02, mean=2.8435e-02
Output Diffs (y): min=2.8242e-02, max=2.9792e-01, mean=7.0312e-02
Coefficients: [1333131.29, -168644.23, 7950.51, -163.75, 1.26]
```
**What to Check:**
- **Count**: Number of timestep pairs analyzed. Should be at least 30-50 for reliable estimation. Low count suggests insufficient prompts or inference steps.
- **Input/Output Ranges**: Verify output differences correlate with input differences. If ranges seem unusual, check your prompt diversity.
- **Coefficient Magnitude**: Extremely large values (>1e8) may indicate numerical instability - try collecting more diverse data.
**Troubleshooting:**
- If results seem unreliable, try:
- Increasing number of prompts (100+ recommended)
- Using more diverse prompts from multiple datasets
- Adjusting `num_inference_steps` (try 20, 50, 100)
### 5.5 Add Coefficients to Config
Add the estimated coefficients to `vllm_omni/diffusion/cache/teacache/config.py`:
```python
_MODEL_COEFFICIENTS = {
...
"YourTransformer2DModel": [
1.04730573e+06, # a4
-1.34150749e+05, # a3
6.51517806e+03, # a2
-1.41209108e+02, # a1
1.17241808e+00, # a0
],
}
```
## Step 6: Open a Pull Request
When submitting a pull request to add support for a new model, please include the following information in the PR description:
@@ -0,0 +1,197 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import types
from typing import Any
import numpy as np
import torch
from vllm.config import LoadConfig
from vllm_omni.diffusion.cache.teacache.extractors import get_extractor
from vllm_omni.diffusion.data import OmniDiffusionConfig
from vllm_omni.diffusion.hooks import HookRegistry, ModelHook
from vllm_omni.diffusion.model_loader.diffusers_loader import DiffusersPipelineLoader
from vllm_omni.diffusion.models.bagel.pipeline_bagel import BagelPipeline
class DataCollectionHook(ModelHook):
"""Hook to collect modulated inputs and model outputs for TeaCache coefficient estimation."""
_HOOK_NAME = "teacache_collector"
def __init__(self, transformer_type: str):
super().__init__()
self.transformer_type = transformer_type
self.extractor_fn = None
self.current_trajectory: list[tuple[np.ndarray, np.ndarray]] = []
def initialize_hook(self, module: torch.nn.Module) -> torch.nn.Module:
self.extractor_fn = get_extractor(self.transformer_type)
return module
def new_forward(self, module: torch.nn.Module, *args: Any, **kwargs: Any) -> Any:
ctx = self.extractor_fn(module, *args, **kwargs)
modulated_input_cpu = ctx.modulated_input.detach().cpu().numpy()
outputs = ctx.run_transformer_blocks()
ctx.hidden_states = outputs[0]
if len(outputs) > 1 and ctx.encoder_hidden_states is not None:
ctx.encoder_hidden_states = outputs[1]
model_output_cpu = ctx.hidden_states.detach().cpu().numpy()
self.current_trajectory.append((modulated_input_cpu, model_output_cpu))
return ctx.postprocess(ctx.hidden_states)
def start_collection(self):
self.current_trajectory = []
def stop_collection(self) -> list[tuple[np.ndarray, np.ndarray]]:
return list(self.current_trajectory)
class BagelAdapter:
"""Adapter for Bagel model."""
@staticmethod
def load_pipeline(model_path: str, device: str = "cuda", dtype: torch.dtype = torch.bfloat16) -> BagelPipeline:
od_config = OmniDiffusionConfig.from_kwargs(model=model_path, dtype=dtype)
od_config.model_class_name = "BagelPipeline"
pipeline = BagelPipeline(od_config=od_config)
loader = DiffusersPipelineLoader(LoadConfig())
loader.load_weights(pipeline)
pipeline.to(device)
return pipeline
@staticmethod
def get_transformer(pipeline: Any) -> tuple[Any, str]:
return pipeline.bagel, "Bagel"
@staticmethod
def install_hook(transformer: Any, hook: DataCollectionHook) -> None:
original_forward_flow = transformer._forward_flow
def forward_alias(self, *args, **kwargs):
return original_forward_flow(*args, **kwargs)
transformer.forward = types.MethodType(forward_alias, transformer)
registry = HookRegistry.get_or_create(transformer)
registry.register_hook(hook._HOOK_NAME, hook)
transformer._forward_flow = transformer.forward
class DefaultAdapter:
"""Default adapter for standard diffusers pipelines."""
@staticmethod
def load_pipeline(model_path: str, device: str, dtype: torch.dtype) -> Any:
raise NotImplementedError("DefaultAdapter.load_pipeline not implemented")
@staticmethod
def get_transformer(pipeline: Any) -> tuple[Any, str]:
return pipeline.transformer, pipeline.transformer.__class__.__name__
@staticmethod
def install_hook(transformer: Any, hook: DataCollectionHook) -> None:
registry = HookRegistry.get_or_create(transformer)
registry.register_hook(hook._HOOK_NAME, hook)
_MODEL_ADAPTERS: dict[str, type] = {
"Bagel": BagelAdapter,
}
_EPSILON = 1e-6
def calculate_relative_l1(tensor_current: np.ndarray, tensor_next: np.ndarray) -> float:
"""Calculate relative L1 distance (Eq. 4 from TeaCache paper)."""
diff = np.abs(tensor_current - tensor_next).sum()
norm = np.abs(tensor_current).sum() + _EPSILON
return diff / norm
def estimate_teacache_coefficients(
collected_data: list[list[tuple[np.ndarray, np.ndarray]]], poly_order: int = 4
) -> list[float]:
"""Estimate polynomial coefficients for TeaCache using np.polyfit."""
input_diffs, output_diffs = [], []
for sample in collected_data:
for t in range(len(sample) - 1):
feat_in_curr, feat_out_curr = sample[t]
feat_in_next, feat_out_next = sample[t + 1]
input_diffs.append(calculate_relative_l1(feat_in_curr, feat_in_next))
output_diffs.append(calculate_relative_l1(feat_out_curr, feat_out_next))
x = np.array(input_diffs, dtype=np.float64)
y = np.array(output_diffs, dtype=np.float64)
print("Data statistics:")
print(f" Count: {len(x)}")
print(f" Input Diffs (x): min={x.min():.4e}, max={x.max():.4e}, mean={x.mean():.4e}")
print(f" Output Diffs (y): min={y.min():.4e}, max={y.max():.4e}, mean={y.mean():.4e}")
return np.polyfit(x, y, poly_order).tolist()
class TeaCacheCoefficientEstimator:
"""Model-agnostic helper class to collect data and estimate TeaCache coefficients."""
def __init__(
self,
model_path: str,
model_type: str = "Bagel",
device: str = "cuda",
dtype: torch.dtype = torch.bfloat16,
):
# Add validation here ⬇️
if model_type not in _MODEL_ADAPTERS:
available_types = list(_MODEL_ADAPTERS.keys())
raise ValueError(
f"Unsupported model_type: '{model_type}'. "
f"Available types: {available_types}. "
f"To add support for a new model, add an entry to _MODEL_ADAPTERS."
)
adapter = _MODEL_ADAPTERS.get(model_type, DefaultAdapter)
self.pipeline = adapter.load_pipeline(model_path, device, dtype)
self.transformer, self.transformer_type = adapter.get_transformer(self.pipeline)
self.hook = DataCollectionHook(self.transformer_type)
self.collected_data: list[list[tuple[np.ndarray, np.ndarray]]] = []
adapter.install_hook(self.transformer, self.hook)
def collect_from_prompt(self, prompt: str, **generate_kwargs):
self.hook.start_collection()
from vllm_omni.diffusion.request import OmniDiffusionRequest
req = OmniDiffusionRequest(
prompt=prompt,
num_inference_steps=generate_kwargs.get("num_inference_steps", 20),
seed=generate_kwargs.get("seed", 42),
)
self.pipeline.forward(req)
trajectory = self.hook.stop_collection()
if trajectory:
self.collected_data.append(trajectory)
def estimate(self, poly_order: int = 4) -> list[float]:
"""Estimate polynomial coefficients from collected data.
Args:
poly_order: Order of polynomial fit (default: 4)
Returns:
List of polynomial coefficients [a_n, a_{n-1}, ..., a_1, a_0]
Raises:
RuntimeError: If no data has been collected
"""
if not self.collected_data:
raise RuntimeError(
"No data collected for coefficient estimation. "
"Call collect_from_prompt() at least once before calling estimate()."
)
return estimate_teacache_coefficients(self.collected_data, poly_order)