Files
diffusers/tests/hooks/test_mag_cache.py
Alan Ponnachan 430c557b6a Add support for Magcache (#12744)
* add magcache

* formatting

* add magcache support with calibration mode

* add imports

* improvements

* Apply style fixes

* fix kandinsky errors

* add tests and documentation

* Apply style fixes

* improvements

* Apply style fixes

* make fix-copies.

* minor fixes

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
2026-02-04 13:45:12 +05:30

245 lines
8.8 KiB
Python

# Copyright 2025 HuggingFace Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import unittest
import numpy as np
import torch
from diffusers import MagCacheConfig, apply_mag_cache
from diffusers.hooks._helpers import TransformerBlockMetadata, TransformerBlockRegistry
from diffusers.models import ModelMixin
from diffusers.utils import logging
logger = logging.get_logger(__name__)
class DummyBlock(torch.nn.Module):
def __init__(self):
super().__init__()
def forward(self, hidden_states, encoder_hidden_states=None, **kwargs):
# Output is double input
# This ensures Residual = 2*Input - Input = Input
return hidden_states * 2.0
class DummyTransformer(ModelMixin):
def __init__(self):
super().__init__()
self.transformer_blocks = torch.nn.ModuleList([DummyBlock(), DummyBlock()])
def forward(self, hidden_states, encoder_hidden_states=None):
for block in self.transformer_blocks:
hidden_states = block(hidden_states, encoder_hidden_states=encoder_hidden_states)
return hidden_states
class TupleOutputBlock(torch.nn.Module):
def __init__(self):
super().__init__()
def forward(self, hidden_states, encoder_hidden_states=None, **kwargs):
# Returns a tuple
return hidden_states * 2.0, encoder_hidden_states
class TupleTransformer(ModelMixin):
def __init__(self):
super().__init__()
self.transformer_blocks = torch.nn.ModuleList([TupleOutputBlock()])
def forward(self, hidden_states, encoder_hidden_states=None):
for block in self.transformer_blocks:
# Emulate Flux-like behavior
output = block(hidden_states, encoder_hidden_states=encoder_hidden_states)
hidden_states = output[0]
encoder_hidden_states = output[1]
return hidden_states, encoder_hidden_states
class MagCacheTests(unittest.TestCase):
def setUp(self):
# Register standard dummy block
TransformerBlockRegistry.register(
DummyBlock,
TransformerBlockMetadata(return_hidden_states_index=None, return_encoder_hidden_states_index=None),
)
# Register tuple block (Flux style)
TransformerBlockRegistry.register(
TupleOutputBlock,
TransformerBlockMetadata(return_hidden_states_index=0, return_encoder_hidden_states_index=1),
)
def _set_context(self, model, context_name):
"""Helper to set context on all hooks in the model."""
for module in model.modules():
if hasattr(module, "_diffusers_hook"):
module._diffusers_hook._set_context(context_name)
def _get_calibration_data(self, model):
for module in model.modules():
if hasattr(module, "_diffusers_hook"):
hook = module._diffusers_hook.get_hook("mag_cache_block_hook")
if hook:
return hook.state_manager.get_state().calibration_ratios
return []
def test_mag_cache_validation(self):
"""Test that missing mag_ratios raises ValueError."""
with self.assertRaises(ValueError):
MagCacheConfig(num_inference_steps=10, calibrate=False)
def test_mag_cache_skipping_logic(self):
"""
Tests that MagCache correctly calculates residuals and skips blocks when conditions are met.
"""
model = DummyTransformer()
# Dummy ratios: [1.0, 1.0] implies 0 accumulated error if we skip
ratios = np.array([1.0, 1.0])
config = MagCacheConfig(
threshold=100.0,
num_inference_steps=2,
retention_ratio=0.0, # Enable immediate skipping
max_skip_steps=5,
mag_ratios=ratios,
)
apply_mag_cache(model, config)
self._set_context(model, "test_context")
# Step 0: Input 10.0 -> Output 40.0 (2 blocks * 2x each)
# HeadInput=10. Output=40. Residual=30.
input_t0 = torch.tensor([[[10.0]]])
output_t0 = model(input_t0)
self.assertTrue(torch.allclose(output_t0, torch.tensor([[[40.0]]])), "Step 0 failed")
# Step 1: Input 11.0.
# If Skipped: Output = Input(11) + Residual(30) = 41.0
# If Computed: Output = 11 * 4 = 44.0
input_t1 = torch.tensor([[[11.0]]])
output_t1 = model(input_t1)
self.assertTrue(
torch.allclose(output_t1, torch.tensor([[[41.0]]])), f"Expected Skip (41.0), got {output_t1.item()}"
)
def test_mag_cache_retention(self):
"""Test that retention_ratio prevents skipping even if error is low."""
model = DummyTransformer()
# Ratios that imply 0 error, so it *would* skip if retention allowed it
ratios = np.array([1.0, 1.0])
config = MagCacheConfig(
threshold=100.0,
num_inference_steps=2,
retention_ratio=1.0, # Force retention for ALL steps
mag_ratios=ratios,
)
apply_mag_cache(model, config)
self._set_context(model, "test_context")
# Step 0
model(torch.tensor([[[10.0]]]))
# Step 1: Should COMPUTE (44.0) not SKIP (41.0) because of retention
input_t1 = torch.tensor([[[11.0]]])
output_t1 = model(input_t1)
self.assertTrue(
torch.allclose(output_t1, torch.tensor([[[44.0]]])),
f"Expected Compute (44.0) due to retention, got {output_t1.item()}",
)
def test_mag_cache_tuple_outputs(self):
"""Test compatibility with models returning (hidden, encoder_hidden) like Flux."""
model = TupleTransformer()
ratios = np.array([1.0, 1.0])
config = MagCacheConfig(threshold=100.0, num_inference_steps=2, retention_ratio=0.0, mag_ratios=ratios)
apply_mag_cache(model, config)
self._set_context(model, "test_context")
# Step 0: Compute. Input 10.0 -> Output 20.0 (1 block * 2x)
# Residual = 10.0
input_t0 = torch.tensor([[[10.0]]])
enc_t0 = torch.tensor([[[1.0]]])
out_0, _ = model(input_t0, encoder_hidden_states=enc_t0)
self.assertTrue(torch.allclose(out_0, torch.tensor([[[20.0]]])))
# Step 1: Skip. Input 11.0.
# Skipped Output = 11 + 10 = 21.0
input_t1 = torch.tensor([[[11.0]]])
out_1, _ = model(input_t1, encoder_hidden_states=enc_t0)
self.assertTrue(
torch.allclose(out_1, torch.tensor([[[21.0]]])), f"Tuple skip failed. Expected 21.0, got {out_1.item()}"
)
def test_mag_cache_reset(self):
"""Test that state resets correctly after num_inference_steps."""
model = DummyTransformer()
config = MagCacheConfig(
threshold=100.0, num_inference_steps=2, retention_ratio=0.0, mag_ratios=np.array([1.0, 1.0])
)
apply_mag_cache(model, config)
self._set_context(model, "test_context")
input_t = torch.ones(1, 1, 1)
model(input_t) # Step 0
model(input_t) # Step 1 (Skipped)
# Step 2 (Reset -> Step 0) -> Should Compute
# Input 2.0 -> Output 8.0
input_t2 = torch.tensor([[[2.0]]])
output_t2 = model(input_t2)
self.assertTrue(torch.allclose(output_t2, torch.tensor([[[8.0]]])), "State did not reset correctly")
def test_mag_cache_calibration(self):
"""Test that calibration mode records ratios."""
model = DummyTransformer()
config = MagCacheConfig(num_inference_steps=2, calibrate=True)
apply_mag_cache(model, config)
self._set_context(model, "test_context")
# Step 0
# HeadInput = 10. Output = 40. Residual = 30.
# Ratio 0 is placeholder 1.0
model(torch.tensor([[[10.0]]]))
# Check intermediate state
ratios = self._get_calibration_data(model)
self.assertEqual(len(ratios), 1)
self.assertEqual(ratios[0], 1.0)
# Step 1
# HeadInput = 10. Output = 40. Residual = 30.
# PrevResidual = 30. CurrResidual = 30.
# Ratio = 30/30 = 1.0
model(torch.tensor([[[10.0]]]))
# Verify it computes fully (no skip)
# If it skipped, output would be 41.0. It should be 40.0
# Actually in test setup, input is same (10.0) so output 40.0.
# Let's ensure list is empty after reset (end of step 1)
ratios_after = self._get_calibration_data(model)
self.assertEqual(ratios_after, [])