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Support gqa on all attention backends, drop support for pytorch 2.4 (#14772)

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comfyanonymous
2026-07-07 19:57:52 -07:00
committed by GitHub
parent 6880614319
commit b481bc15af
9 changed files with 114 additions and 103 deletions
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163
comfy/ldm/modules/attention.py
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@@ -1,5 +1,6 @@
import math
import sys
import inspect
import torch
import torch.nn.functional as F
@@ -14,16 +15,16 @@ from .sub_quadratic_attention import efficient_dot_product_attention
from comfy import model_management
TORCH_HAS_GQA = model_management.torch_version_numeric >= (2, 5)
if model_management.xformers_enabled():
import xformers
import xformers.ops
SAGE_ATTENTION_IS_AVAILABLE = False
SAGE_ATTENTION_SUPPORTS_MASK = False
try:
from sageattention import sageattn
SAGE_ATTENTION_IS_AVAILABLE = True
SAGE_ATTENTION_SUPPORTS_MASK = "attn_mask" in inspect.signature(sageattn).parameters
except ImportError as e:
if model_management.sage_attention_enabled():
if e.name == "sageattention":
@@ -89,6 +90,44 @@ def default(val, d):
return val
return d
def _gqa_repeat_factor(query_heads, key_heads, value_heads):
if key_heads != value_heads:
raise ValueError(f"Key/value head count mismatch for GQA: {key_heads} != {value_heads}")
if query_heads == key_heads:
return 1
if query_heads % key_heads != 0:
raise ValueError(f"Query heads must be divisible by key/value heads for GQA: {query_heads} vs {key_heads}")
return query_heads // key_heads
def _repeat_kv_for_gqa(k, v, query_heads, head_dim):
n_rep = _gqa_repeat_factor(query_heads, k.shape[head_dim], v.shape[head_dim])
if n_rep > 1:
k = k.repeat_interleave(n_rep, dim=head_dim)
v = v.repeat_interleave(n_rep, dim=head_dim)
return k, v
def _heads_from_dim(tensor, dim_head, name):
inner_dim = tensor.shape[-1]
if inner_dim % dim_head != 0:
raise ValueError(f"{name} inner dimension {inner_dim} is not divisible by head dimension {dim_head}")
return inner_dim // dim_head
def _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, enable_gqa=False, expand_kv=True):
q = q.unsqueeze(3).reshape(b, -1, heads, dim_head)
if enable_gqa:
key_heads = _heads_from_dim(k, dim_head, "Key")
value_heads = _heads_from_dim(v, dim_head, "Value")
else:
key_heads = heads
value_heads = heads
k = k.unsqueeze(3).reshape(b, -1, key_heads, dim_head)
v = v.unsqueeze(3).reshape(b, -1, value_heads, dim_head)
if enable_gqa:
_gqa_repeat_factor(heads, key_heads, value_heads)
if expand_kv:
k, v = _repeat_kv_for_gqa(k, v, heads, -2)
return q, k, v
# feedforward
class GEGLU(nn.Module):
@@ -152,28 +191,19 @@ def attention_basic(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
b, _, dim_head = q.shape
dim_head //= heads
if kwargs.get("enable_gqa", False) and q.shape[-3] != k.shape[-3]:
n_rep = q.shape[-3] // k.shape[-3]
k = k.repeat_interleave(n_rep, dim=-3)
v = v.repeat_interleave(n_rep, dim=-3)
scale = kwargs.get("scale", dim_head ** -0.5)
h = heads
if skip_reshape:
q, k, v = map(
if kwargs.get("enable_gqa", False):
k, v = _repeat_kv_for_gqa(k, v, q.shape[-3], -3)
q, k, v = map(
lambda t: t.reshape(b * heads, -1, dim_head),
(q, k, v),
)
else:
q, k, v = map(
lambda t: t.unsqueeze(3)
.reshape(b, -1, heads, dim_head)
.permute(0, 2, 1, 3)
.reshape(b * heads, -1, dim_head)
.contiguous(),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False))
q, k, v = map(lambda t: t.permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head).contiguous(), (q, k, v))
# force cast to fp32 to avoid overflowing
if attn_precision == torch.float32:
@@ -231,13 +261,16 @@ def attention_sub_quad(query, key, value, heads, mask=None, attn_precision=None,
query = query * (kwargs["scale"] * dim_head ** 0.5)
if skip_reshape:
if kwargs.get("enable_gqa", False):
key, value = _repeat_kv_for_gqa(key, value, query.shape[-3], -3)
query = query.reshape(b * heads, -1, dim_head)
value = value.reshape(b * heads, -1, dim_head)
key = key.reshape(b * heads, -1, dim_head).movedim(1, 2)
else:
query = query.unsqueeze(3).reshape(b, -1, heads, dim_head).permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head)
value = value.unsqueeze(3).reshape(b, -1, heads, dim_head).permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head)
key = key.unsqueeze(3).reshape(b, -1, heads, dim_head).permute(0, 2, 3, 1).reshape(b * heads, dim_head, -1)
query, key, value = _reshape_qkv_to_heads(query, key, value, b, heads, dim_head, kwargs.get("enable_gqa", False))
query = query.permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head)
value = value.permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head)
key = key.permute(0, 2, 3, 1).reshape(b * heads, dim_head, -1)
dtype = query.dtype
@@ -304,19 +337,15 @@ def attention_split(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
scale = kwargs.get("scale", dim_head ** -0.5)
if skip_reshape:
q, k, v = map(
if kwargs.get("enable_gqa", False):
k, v = _repeat_kv_for_gqa(k, v, q.shape[-3], -3)
q, k, v = map(
lambda t: t.reshape(b * heads, -1, dim_head),
(q, k, v),
)
else:
q, k, v = map(
lambda t: t.unsqueeze(3)
.reshape(b, -1, heads, dim_head)
.permute(0, 2, 1, 3)
.reshape(b * heads, -1, dim_head)
.contiguous(),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False))
q, k, v = map(lambda t: t.permute(0, 2, 1, 3).reshape(b * heads, -1, dim_head).contiguous(), (q, k, v))
r1 = torch.zeros(q.shape[0], q.shape[1], v.shape[2], device=q.device, dtype=q.dtype)
@@ -438,7 +467,7 @@ def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_resh
disabled_xformers = True
if disabled_xformers:
return attention_pytorch(q, k, v, heads, mask, skip_reshape=skip_reshape, **kwargs)
return attention_pytorch(q, k, v, heads, mask, skip_reshape=skip_reshape, skip_output_reshape=skip_output_reshape, **kwargs)
if skip_reshape:
# b h k d -> b k h d
@@ -446,13 +475,12 @@ def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_resh
lambda t: t.permute(0, 2, 1, 3),
(q, k, v),
)
if kwargs.get("enable_gqa", False):
k, v = _repeat_kv_for_gqa(k, v, q.shape[-2], -2)
# actually do the reshaping
else:
dim_head //= heads
q, k, v = map(
lambda t: t.reshape(b, -1, heads, dim_head),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False))
if mask is not None:
# add a singleton batch dimension
@@ -474,7 +502,7 @@ def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_resh
mask = mask_out[..., :mask.shape[-1]]
mask = mask.expand(b, heads, -1, -1)
out = xformers.ops.memory_efficient_attention(q, k, v, attn_bias=mask)
out = xformers.ops.memory_efficient_attention(q, k, v, attn_bias=mask, scale=kwargs.get("scale", None))
if skip_output_reshape:
out = out.permute(0, 2, 1, 3)
@@ -498,10 +526,8 @@ def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_resha
else:
b, _, dim_head = q.shape
dim_head //= heads
q, k, v = map(
lambda t: t.view(b, -1, heads, dim_head).transpose(1, 2),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False), expand_kv=False)
q, k, v = map(lambda t: t.transpose(1, 2), (q, k, v))
if mask is not None:
# add a batch dimension if there isn't already one
@@ -511,9 +537,7 @@ def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_resha
if mask.ndim == 3:
mask = mask.unsqueeze(1)
# Pass through extra SDPA kwargs (scale, enable_gqa) if provided
# enable_gqa requires PyTorch 2.5+; older versions use manual KV expansion above
sdpa_keys = ("scale", "enable_gqa") if TORCH_HAS_GQA else ("scale",)
sdpa_keys = ("scale", "enable_gqa")
sdpa_extra = {k: v for k, v in kwargs.items() if k in sdpa_keys}
if SDP_BATCH_LIMIT >= b:
@@ -541,20 +565,19 @@ def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_resha
@wrap_attn
def attention_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False, **kwargs):
if kwargs.get("low_precision_attention", True) is False:
if kwargs.get("low_precision_attention", True) is False or (mask is not None and not SAGE_ATTENTION_SUPPORTS_MASK):
return attention_pytorch(q, k, v, heads, mask=mask, skip_reshape=skip_reshape, skip_output_reshape=skip_output_reshape, **kwargs)
exception_fallback = False
if skip_reshape:
b, _, _, dim_head = q.shape
tensor_layout = "HND"
if kwargs.get("enable_gqa", False):
k, v = _repeat_kv_for_gqa(k, v, q.shape[-3], -3)
else:
b, _, dim_head = q.shape
dim_head //= heads
q, k, v = map(
lambda t: t.view(b, -1, heads, dim_head),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False))
tensor_layout = "NHD"
if mask is not None:
@@ -565,8 +588,12 @@ def attention_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=
if mask.ndim == 3:
mask = mask.unsqueeze(1)
sage_kwargs = {"is_causal": False, "tensor_layout": tensor_layout, "sm_scale": kwargs.get("scale", None), "smooth_k": False}
if mask is not None:
sage_kwargs["attn_mask"] = mask
try:
out = sageattn(q, k, v, attn_mask=mask, is_causal=False, tensor_layout=tensor_layout)
out = sageattn(q, k, v, **sage_kwargs)
except Exception as e:
logging.error("Error running sage attention: {}, using pytorch attention instead.".format(e))
exception_fallback = True
@@ -616,7 +643,6 @@ def attention3_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
skip_output_reshape=skip_output_reshape,
**kwargs
)
q_s, k_s, v_s = q, k, v
N = q.shape[2]
dim_head = D
else:
@@ -642,11 +668,15 @@ def attention3_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
**kwargs
)
if not skip_reshape:
q_s, k_s, v_s = map(
lambda t: t.view(B, -1, heads, dim_head).permute(0, 2, 1, 3).contiguous(),
(q, k, v),
)
if skip_reshape:
q_s = q
if kwargs.get("enable_gqa", False):
k_s, v_s = _repeat_kv_for_gqa(k, v, H, -3)
else:
k_s, v_s = k, v
else:
q_s, k_s, v_s = _reshape_qkv_to_heads(q, k, v, B, heads, dim_head, kwargs.get("enable_gqa", False))
q_s, k_s, v_s = map(lambda t: t.permute(0, 2, 1, 3).contiguous(), (q_s, k_s, v_s))
B, H, L, D = q_s.shape
try:
@@ -662,7 +692,7 @@ def attention3_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
q, k, v, heads,
mask=mask,
attn_precision=attn_precision,
skip_reshape=False,
skip_reshape=skip_reshape,
skip_output_reshape=skip_output_reshape,
**kwargs
)
@@ -681,19 +711,20 @@ def attention3_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
try:
@torch.library.custom_op("flash_attention::flash_attn", mutates_args=())
def flash_attn_wrapper(q: torch.Tensor, k: torch.Tensor, v: torch.Tensor,
dropout_p: float = 0.0, causal: bool = False) -> torch.Tensor:
return flash_attn_func(q, k, v, dropout_p=dropout_p, causal=causal)
dropout_p: float = 0.0, causal: bool = False, softmax_scale: float = -1.0) -> torch.Tensor:
softmax_scale_arg = None if softmax_scale == -1.0 else softmax_scale
return flash_attn_func(q, k, v, dropout_p=dropout_p, causal=causal, softmax_scale=softmax_scale_arg)
@flash_attn_wrapper.register_fake
def flash_attn_fake(q, k, v, dropout_p=0.0, causal=False):
def flash_attn_fake(q, k, v, dropout_p=0.0, causal=False, softmax_scale=-1.0):
# Output shape is the same as q
return q.new_empty(q.shape)
except AttributeError as error:
FLASH_ATTN_ERROR = error
def flash_attn_wrapper(q: torch.Tensor, k: torch.Tensor, v: torch.Tensor,
dropout_p: float = 0.0, causal: bool = False) -> torch.Tensor:
dropout_p: float = 0.0, causal: bool = False, softmax_scale: float = -1.0) -> torch.Tensor:
assert False, f"Could not define flash_attn_wrapper: {FLASH_ATTN_ERROR}"
@wrap_attn
@@ -703,10 +734,8 @@ def attention_flash(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
else:
b, _, dim_head = q.shape
dim_head //= heads
q, k, v = map(
lambda t: t.view(b, -1, heads, dim_head).transpose(1, 2),
(q, k, v),
)
q, k, v = _reshape_qkv_to_heads(q, k, v, b, heads, dim_head, kwargs.get("enable_gqa", False), expand_kv=False)
q, k, v = map(lambda t: t.transpose(1, 2), (q, k, v))
if mask is not None:
# add a batch dimension if there isn't already one
@@ -725,10 +754,16 @@ def attention_flash(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
v.transpose(1, 2),
dropout_p=0.0,
causal=False,
softmax_scale=kwargs.get("scale", -1.0),
).transpose(1, 2)
except Exception as e:
logging.warning(f"Flash Attention failed, using default SDPA: {e}")
out = torch.nn.functional.scaled_dot_product_attention(q, k, v, attn_mask=mask, dropout_p=0.0, is_causal=False)
sdpa_extra = {}
if kwargs.get("enable_gqa", False):
sdpa_extra["enable_gqa"] = True
if "scale" in kwargs:
sdpa_extra["scale"] = kwargs["scale"]
out = torch.nn.functional.scaled_dot_product_attention(q, k, v, attn_mask=mask, dropout_p=0.0, is_causal=False, **sdpa_extra)
if not skip_output_reshape:
out = (
out.transpose(1, 2).reshape(b, -1, heads * dim_head)
@@ -1209,5 +1244,3 @@ class SpatialVideoTransformer(SpatialTransformer):
x = self.proj_out(x)
out = x + x_in
return out