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Python

from dataclasses import dataclass
from types import MethodType
import torch
from torch import nn
from torch import Tensor
from einops import rearrange
from comfy.ldm.flux.model import Flux
from comfy.ldm.hunyuan_video.model import HunyuanVideo
from comfy.ldm.flux.layers import DoubleStreamBlock, SingleStreamBlock, LastLayer
from comfy.ldm.wan.model import (
WanModel,
VaceWanModel,
CameraWanModel,
WanModel_S2V,
HumoWanModel,
WanAttentionBlock,
VaceWanAttentionBlock,
Head,
)
from comfy.ldm.flux.math import apply_rope1
from comfy.ldm.modules.attention import optimized_attention
from comfy.model_patcher import ModelPatcher
import comfy.model_management
def apply_pe(x: Tensor, pe: Tensor) -> Tensor:
"""
The PE application from flux.math.attention, removed, so that we can cache the keys post-PE
"""
shape = x.shape
dtype = x.dtype
x = x.float().reshape(*x.shape[:-1], -1, 1, 2)
x = (pe[..., 0] * x[..., 0] + pe[..., 1] * x[..., 1]).reshape(*shape).to(dtype)
return x
def take_attributes_from(source, target, keys):
for x in keys:
setattr(target, x, getattr(source, x))
@dataclass
class RASConfig:
warmup_steps: int = 4
hydrate_every: int = 5
sample_ratio: float = 0.5
starvation_scale: float = 0.1
high_ratio: float = 1.0
class RASManager:
"""
Coordinates the live indices, metrics, and model wrapping.
"""
def __init__(self, config: RASConfig):
self.flipped_img_txt = False
self.timestep: int = 0
self.n_txt: int = 0
self.n_img: int = 0
self.cached_output: Tensor | None = None
self.live_txt_indices: Tensor | None = None
self.live_img_indices: Tensor | None = None
self.drop_count: torch.Tensor | None = None
self.config = config
self.patch_size: list[int]
self.model: Flux | HunyuanVideo
assert (
self.config.high_ratio >= 0 and self.config.high_ratio <= 1
), "High ratio should be in the range of [0, 1]"
def wrap_layer(self, layer, first: bool = False, last: bool = False):
if isinstance(
layer,
(
DoubleStreamBlockWrapper,
SingleStreamBlockWrapper,
LastLayerWrapper,
WanAttentionBlockWrapper,
VaceWanAttentionBlockWrapper,
),
):
raise TypeError("Old wrapping wasn't removed!")
if isinstance(layer, DoubleStreamBlock):
wrapped = DoubleStreamBlockWrapper(layer, self, first)
elif isinstance(layer, SingleStreamBlock):
wrapped = SingleStreamBlockWrapper(layer, self, last)
elif isinstance(layer, LastLayer):
wrapped = LastLayerWrapper(layer, self)
# note: vacewaneattentionblock is a subclass of wanattentionblock
# so we have to check for the vace block first
elif isinstance(layer, VaceWanAttentionBlock):
wrapped = VaceWanAttentionBlockWrapper(layer, self, first, last)
elif isinstance(layer, WanAttentionBlock):
wrapped = WanAttentionBlockWrapper(layer, self, first, last)
elif isinstance(layer, Head):
wrapped = HeadWrapper(layer, self)
else:
raise TypeError(f"Can't wrap layer of type {layer.__class__.__name__}")
return wrapped
def wrap_model(self, patcher: ModelPatcher):
model = patcher.model.diffusion_model
self.model = model
if isinstance(model, Flux):
self.patch_size = [model.patch_size, model.patch_size]
elif isinstance(model, HunyuanVideo):
self.patch_size = model.patch_size
elif isinstance(
model, (WanModel, VaceWanModel, CameraWanModel, WanModel_S2V, HumoWanModel)
):
self.patch_size = model.patch_size
else:
raise TypeError(f"Can't wrap model of type {model.__class__.__name__}")
# Handle different model architectures
if isinstance(model, (Flux, HunyuanVideo)):
# wrap the single and double blocks to have caching
for i, v in enumerate(model.double_blocks):
# first block has the special responsibility of removing tokens
if i == 0:
self.flipped_img_txt = v.flipped_img_txt
layer = self.wrap_layer(v, first=True)
else:
layer = self.wrap_layer(v)
patcher.add_object_patch(f"diffusion_model.double_blocks.{i}", layer)
for i, v in enumerate(model.single_blocks):
# last block will put them back
patcher.add_object_patch(
f"diffusion_model.single_blocks.{i}",
self.wrap_layer(v, last=(i == (len(model.single_blocks) - 1))),
)
elif isinstance(
model, (WanModel, VaceWanModel, CameraWanModel, WanModel_S2V, HumoWanModel)
):
# Wan models have a different structure with just 'blocks'
self.flipped_img_txt = False # Wan doesn't use the flipped pattern
for i, v in enumerate(model.blocks):
# first block has the special responsibility of removing tokens
# last block will put them back
layer = self.wrap_layer(
v, first=(i == 0), last=(i == (len(model.blocks) - 1))
)
patcher.add_object_patch(f"diffusion_model.blocks.{i}", layer)
# todo, add the vace blocks as well here
if hasattr(model, "vace_blocks"):
for i, v in enumerate(model.vace_blocks):
layer = self.wrap_layer(
v,
first=(i == 0),
# we DONT put back the conditioning tokens
# because the last vace block is well before the last real block
last=False,
# last=(i == (len(model.vace_blocks) - 1))
)
patcher.add_object_patch(f"diffusion_model.vace_blocks.{i}", layer)
# wrap the forward_orig method, to be able to get the timestep
forward_orig = model.forward_orig
def new_forward(_self, *args, **kwargs):
# Get transformer_options from kwargs for Wan models, or from args for Flux/Hunyuan
if "transformer_options" in kwargs:
transformer_options = kwargs["transformer_options"]
else:
transformer_options = args[-1]
self.timestep = self.timestep_from_sigmas(
transformer_options["sigmas"], transformer_options["sample_sigmas"]
)
if self.timestep == 0:
# reset as much as possible
self.live_img_indices = None
self.live_txt_indices = None
self.drop_count = None
return forward_orig(*args, **kwargs)
patcher.add_object_patch(
"diffusion_model.forward_orig", MethodType(new_forward, model)
)
# wrap the last_layer, to be able to read the output and calculate the metric
if isinstance(model, (Flux, HunyuanVideo)):
patcher.add_object_patch(
"diffusion_model.final_layer", self.wrap_layer(model.final_layer)
)
elif isinstance(
model, (WanModel, VaceWanModel, CameraWanModel, WanModel_S2V, HumoWanModel)
):
# Wan models use 'head' instead of 'final_layer'
patcher.add_object_patch(
"diffusion_model.head", self.wrap_layer(model.head)
)
@staticmethod
def timestep_from_sigmas(sigmas: Tensor, sample_sigmas: Tensor):
# we assume that one element of sample_sigmas is exactly equal to sigmas
# but we'll still check explicitly, using an argmin, in case of some loss of precision
s = sigmas.item()
i = torch.argmin(torch.abs(sample_sigmas - s).flatten())
return int(i.item())
def skip_ratio(self, timestep: int) -> float:
if timestep < self.config.warmup_steps:
return 0
if self.config.hydrate_every:
if (
1 + timestep - self.config.warmup_steps
) % self.config.hydrate_every == 0:
return 0
result = 1.0 - self.config.sample_ratio
return result
def select_indices(self, diff: Tensor, timestep: int):
if isinstance(self.model, Flux):
# b (h w) (c ph pw) = model_out.shape
metric = rearrange(
diff,
"b s (c ph pw) -> b s ph pw c",
ph=self.patch_size[0],
pw=self.patch_size[1],
)
metric = torch.std(metric, dim=-1).mean((-1, -2))
elif isinstance(
self.model,
(
HunyuanVideo,
WanModel,
VaceWanModel,
CameraWanModel,
WanModel_S2V,
HumoWanModel,
),
):
# b (h w) (c ph pw) = model_out.shape
# Both HunyuanVideo and Wan models are video models with 3D patches
metric = rearrange(
diff,
"b s (c pt ph pw ) -> b s pt ph pw c",
pt=self.patch_size[0],
ph=self.patch_size[1],
pw=self.patch_size[2],
)
metric = torch.std(metric, dim=-1).mean((-1, -2, -3))
else:
raise TypeError("Unknown latent type!")
# for batch size > 1, we pick separate indices per batch
# for now, JUST FOR TESTING, we'll merge all the batches and use the indices that are the most relevant for all batches
metric = metric.mean(dim=0)
metric = metric.flatten()
if self.drop_count is None:
self.drop_count = torch.zeros(
metric.shape, dtype=torch.int, device=diff.device
)
# hmm, what if we do a gaussian blur or some sort of spatial lowpass, to improve the spatial continuity of the patches?
metric *= torch.exp(self.config.starvation_scale * self.drop_count)
indices = torch.sort(metric, dim=-1, descending=False).indices
skip_ratio = self.skip_ratio(timestep)
if skip_ratio <= 0.01:
# we're not dropping anything -- remove the live_indices
# we use the value None to indicate a full hydrate
self.live_img_indices = None
else:
low_bar = int(skip_ratio * len(metric) * (1 - self.config.high_ratio))
high_bar = int(skip_ratio * len(metric) * self.config.high_ratio)
cache_indices = torch.cat([indices[:low_bar], indices[-high_bar:]])
self.live_img_indices = indices[low_bar:-high_bar]
self.drop_count[cache_indices] += 1
# TODO: for now we keep all txt tokens
# in the future, we can probably do something like randomly keep a fraction of them
if self.n_txt > 0:
self.live_txt_indices = torch.arange(
0, self.n_txt, dtype=torch.int, device=diff.device
)
def live_indices(self):
if self.live_img_indices is None or self.live_txt_indices is None:
return self.live_img_indices
if self.flipped_img_txt:
result = torch.cat(
(self.live_img_indices, self.live_txt_indices + self.n_img)
)
else:
result = torch.cat(
(self.live_txt_indices, self.live_img_indices + self.n_txt)
)
return result
class DoubleStreamBlockWrapper(DoubleStreamBlock):
"""
Same as the DoubleStreamBlock, but uses a RASManager and RASCache to do KV caching.
"""
def __init__(self, original: DoubleStreamBlock, manager: RASManager, first=False):
nn.Module.__init__(self)
take_attributes_from(
original,
self,
[
"num_heads",
"hidden_size",
"img_mod",
"img_norm1",
"img_attn",
"img_norm2",
"img_mlp",
"txt_mod",
"txt_norm1",
"txt_attn",
"txt_norm2",
"txt_mlp",
"flipped_img_txt",
],
)
self.manager = manager
self.k_cache: torch.Tensor
self.v_cache: torch.Tensor
self.first = first
def forward(self, img, txt, vec, pe, attn_mask=None):
# RAS: if this is the first doublestreamblock, then we should drop some of the img and txt tokens
idx = self.manager.live_indices()
if self.first:
self.manager.n_txt = txt.shape[1]
self.manager.n_img = img.shape[1]
img_idx = self.manager.live_img_indices
txt_idx = self.manager.live_txt_indices
if idx is not None:
img = img[..., img_idx, :]
txt = txt[..., txt_idx, :]
img_mod1, img_mod2 = self.img_mod(vec)
txt_mod1, txt_mod2 = self.txt_mod(vec)
# prepare image for attention
img_modulated = self.img_norm1(img)
img_modulated = (1 + img_mod1.scale) * img_modulated + img_mod1.shift
img_qkv = self.img_attn.qkv(img_modulated)
img_q, img_k, img_v = img_qkv.view(
img_qkv.shape[0], img_qkv.shape[1], 3, self.num_heads, -1
).permute(2, 0, 3, 1, 4)
img_q, img_k = self.img_attn.norm(img_q, img_k, img_v)
# prepare txt for attention
txt_modulated = self.txt_norm1(txt)
txt_modulated = (1 + txt_mod1.scale) * txt_modulated + txt_mod1.shift
txt_qkv = self.txt_attn.qkv(txt_modulated)
txt_q, txt_k, txt_v = txt_qkv.view(
txt_qkv.shape[0], txt_qkv.shape[1], 3, self.num_heads, -1
).permute(2, 0, 3, 1, 4)
txt_q, txt_k = self.txt_attn.norm(txt_q, txt_k, txt_v)
# RAS: KV Cache and Attention Call
# select part of the PE
if idx is not None:
pe = pe[:, :, idx]
# create queries, keys, and values
if self.flipped_img_txt:
queries = apply_pe(torch.cat((img_q, txt_q), dim=2), pe)
keys = apply_pe(torch.cat((img_k, txt_k), dim=2), pe)
values = torch.cat((img_v, txt_v), dim=2)
else:
queries = apply_pe(torch.cat((txt_q, img_q), dim=2), pe)
keys = apply_pe(torch.cat((txt_k, img_k), dim=2), pe)
values = torch.cat((txt_v, img_v), dim=2)
# fill in the KV cache
if idx is None:
self.k_cache = keys
self.v_cache = values
else:
self.k_cache[..., idx, :] = keys
self.v_cache[..., idx, :] = values
# actual attention call
attn = optimized_attention(
queries,
self.k_cache,
self.v_cache,
img_q.shape[1],
skip_reshape=True,
mask=attn_mask,
)
if self.flipped_img_txt:
img_attn, txt_attn = attn[:, : img.shape[1]], attn[:, img.shape[1] :]
else:
txt_attn, img_attn = attn[:, : txt.shape[1]], attn[:, txt.shape[1] :]
# End of RAS code
# calculate the img blocks
img = img + img_mod1.gate * self.img_attn.proj(img_attn)
img = img + img_mod2.gate * self.img_mlp(
(1 + img_mod2.scale) * self.img_norm2(img) + img_mod2.shift
)
# calculate the txt blocks
txt += txt_mod1.gate * self.txt_attn.proj(txt_attn)
txt += txt_mod2.gate * self.txt_mlp(
(1 + txt_mod2.scale) * self.txt_norm2(txt) + txt_mod2.shift
)
if txt.dtype == torch.float16:
txt = torch.nan_to_num(txt, nan=0.0, posinf=65504, neginf=-65504)
return img, txt
class SingleStreamBlockWrapper(SingleStreamBlock):
"""
Same as the SingleStreamBlock, but uses a RASManager and RASCache to do KV caching.
"""
def __init__(self, original: SingleStreamBlock, manager: RASManager, last=False):
nn.Module.__init__(self)
# steal all the attributes from the SingleStreamBlock
take_attributes_from(
original,
self,
[
"hidden_dim",
"num_heads",
"scale",
"mlp_hidden_dim",
"linear1",
"linear2",
"norm",
"hidden_size",
"pre_norm",
"mlp_act",
"modulation",
],
)
self.manager = manager
self.k_cache: torch.Tensor
self.v_cache: torch.Tensor
self.last = last
def forward(self, x, vec, pe, attn_mask=None):
idx = self.manager.live_indices()
mod, _ = self.modulation(vec)
qkv, mlp = torch.split(
self.linear1((1 + mod.scale) * self.pre_norm(x) + mod.shift),
[3 * self.hidden_size, self.mlp_hidden_dim],
dim=-1,
)
q, k, v = qkv.view(qkv.shape[0], qkv.shape[1], 3, self.num_heads, -1).permute(
2, 0, 3, 1, 4
)
q, k = self.norm(q, k, v)
# RAS: KV Cache
if idx is not None:
pe = pe[:, :, idx]
q = apply_pe(q, pe)
k = apply_pe(k, pe)
# full hydrate
if idx is None:
self.k_cache = k
self.v_cache = v
# partial update
else:
self.k_cache[..., idx, :] = k
self.v_cache[..., idx, :] = v
attn = optimized_attention(
q,
self.k_cache,
self.v_cache,
q.shape[1],
skip_reshape=True,
mask=attn_mask,
)
# End of RAS code
# compute activation in mlp stream, cat again and run second linear layer
output = self.linear2(torch.cat((attn, self.mlp_act(mlp)), 2))
x += mod.gate * output
if x.dtype == torch.float16:
x = torch.nan_to_num(x, nan=0.0, posinf=65504, neginf=-65504)
if self.last:
# put the relevant tokens back into the cached output
if idx is None or self.manager.cached_output is None:
self.manager.cached_output = x.clone()
else:
self.manager.cached_output[..., idx, :] = x
return self.manager.cached_output
return x
class LastLayerWrapper(LastLayer):
"""
Same as the LastLayer, but reports its output to a manager.
"""
def __init__(self, original: LastLayer, manager: RASManager):
nn.Module.__init__(self)
take_attributes_from(
original, self, ["norm_final", "linear", "adaLN_modulation"]
)
self.manager = manager
def forward(self, x, vec) -> Tensor:
output = super().forward(x, vec)
self.manager.select_indices(output, self.manager.timestep)
return output
class WanAttentionBlockWrapper(WanAttentionBlock):
"""
Same as the WanAttentionBlock, but uses a RASManager and RASCache to do KV caching.
"""
def __init__(self, original: WanAttentionBlock, manager: RASManager, first, last):
nn.Module.__init__(self)
take_attributes_from(
original,
self,
[
"dim",
"ffn_dim",
"num_heads",
"window_size",
"qk_norm",
"cross_attn_norm",
"eps",
"norm1",
"self_attn",
"norm3",
"cross_attn",
"norm2",
"ffn",
"modulation",
],
)
self.manager = manager
self.k_cache: torch.Tensor
self.v_cache: torch.Tensor
self.first = first
self.last = last
def forward(
self, x, e, freqs, context, context_img_len=257, transformer_options={}
):
# RAS: if this is the first block, then we should drop some tokens
idx = self.manager.live_indices()
if self.first:
# we just have img tokens
self.manager.n_txt = 0
self.manager.n_img = x.shape[1]
if idx is not None:
x = x[..., idx, :]
# Modulation handling (copied from original)
if e.ndim < 4:
e = (
comfy.model_management.cast_to(
self.modulation, dtype=x.dtype, device=x.device
)
+ e
).chunk(6, dim=1)
else:
e = (
comfy.model_management.cast_to(
self.modulation, dtype=x.dtype, device=x.device
).unsqueeze(0)
+ e
).unbind(2)
# Self-attention with RAS caching
y = self.self_attn_with_cache(
torch.addcmul(
self.repeat_e(e[0], x), self.norm1(x), 1 + self.repeat_e(e[1], x)
),
freqs,
idx,
transformer_options=transformer_options,
)
x = torch.addcmul(x, y, self.repeat_e(e[2], x))
# Cross-attention & ffn (unchanged from original)
x = x + self.cross_attn(
self.norm3(x),
context,
context_img_len=context_img_len,
transformer_options=transformer_options,
)
y = self.ffn(
torch.addcmul(
self.repeat_e(e[3], x), self.norm2(x), 1 + self.repeat_e(e[4], x)
)
)
x = torch.addcmul(x, y, self.repeat_e(e[5], x))
if self.last:
# put the relevant tokens back into the cached output
if idx is None or self.manager.cached_output is None:
self.manager.cached_output = x.clone()
else:
self.manager.cached_output[..., idx, :] = x
return self.manager.cached_output
return x
def repeat_e(self, e, x):
"""Helper function for modulation broadcasting"""
repeats = 1
if e.size(1) > 1:
repeats = x.size(1) // e.size(1)
if repeats == 1:
return e
if repeats * e.size(1) == x.size(1):
return torch.repeat_interleave(e, repeats, dim=1)
else:
return torch.repeat_interleave(e, repeats + 1, dim=1)[:, : x.size(1)]
def self_attn_with_cache(self, x, freqs, idx, transformer_options={}):
"""Modified self-attention that uses KV caching"""
b, s, n, d = *x.shape[:2], self.num_heads, self.self_attn.head_dim
# just pull out part of the frequencies
if idx is not None:
freqs = freqs[:, idx]
# Compute QKV like original Wan self-attention
q = self.self_attn.norm_q(self.self_attn.q(x)).view(b, s, n, d)
q = apply_rope1(q, freqs).view(b, s, n * d)
k = self.self_attn.norm_k(self.self_attn.k(x)).view(b, s, n, d)
k = apply_rope1(k, freqs).view(b, s, n * d)
v = self.self_attn.v(x).view(b, s, n * d)
# RAS: KV Cache management
if idx is None:
self.k_cache = k
self.v_cache = v
else:
self.k_cache[:, idx, :] = k
self.v_cache[:, idx, :] = v
x = optimized_attention(
q,
self.k_cache,
self.v_cache,
heads=n,
transformer_options=transformer_options,
)
x = self.self_attn.o(x)
return x
class VaceWanAttentionBlockWrapper(WanAttentionBlockWrapper):
"""
Same as the VaceWanAttentionBlock, but uses a RASManager and RASCache to do KV caching.
"""
def __init__(
self,
original: VaceWanAttentionBlock,
manager: RASManager,
first=False,
last=False,
):
nn.Module.__init__(self)
# Copy attributes, handling the case where some might not exist
attributes_to_copy = [
"dim",
"ffn_dim",
"num_heads",
"window_size",
"qk_norm",
"cross_attn_norm",
"eps",
"block_id",
"norm1",
"self_attn",
"norm3",
"cross_attn",
"norm2",
"ffn",
"modulation",
]
# Handle optional attributes that might not exist
take_attributes_from(original, self, attributes_to_copy)
# Copy optional attributes if they exist
for attr in ["before_proj", "after_proj"]:
if hasattr(original, attr):
setattr(self, attr, getattr(original, attr))
self.manager = manager
self.k_cache: torch.Tensor
self.v_cache: torch.Tensor
self.first = first
self.last = last
def forward(self, c, x, **kwargs):
if hasattr(self, "before_proj"):
c = self.before_proj(c) + x
c = super().forward(c, **kwargs)
c_skip = self.after_proj(c)
return c_skip, c
class HeadWrapper(Head):
"""
Same as the Head (Wan final layer), but reports its output to a manager.
"""
def __init__(self, original: Head, manager: RASManager):
nn.Module.__init__(self)
take_attributes_from(
original,
self,
["dim", "out_dim", "patch_size", "eps", "norm", "head", "modulation"],
)
self.manager = manager
def forward(self, x, e) -> Tensor:
output = super().forward(x, e)
self.manager.select_indices(output, self.manager.timestep)
return output