given the special attention patterns, attend function needs to be constructed before traversing the transformer layers

This commit is contained in:
lucidrains 2025-10-04 08:31:51 -07:00
parent 7cac3d28c5
commit 93f6738c9c

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@ -372,7 +372,7 @@ def nonflex_block_causal_mask(seq_len, block_size, device = None):
def naive_attend(
q, k, v,
softclamp_value = 50.,
softclamp_value = None,
scale = None,
causal = False,
mask = None
@ -431,9 +431,7 @@ class Attention(Module):
dim_head = 64,
query_heads = None,
heads = 8,
softclamp_value = 50.,
pre_rmsnorm = True,
causal = False
):
super().__init__()
self.norm = RMSNorm(dim) if pre_rmsnorm else Identity()
@ -456,23 +454,23 @@ class Attention(Module):
self.to_kv = LinearNoBias(dim, dim_kv_inner * 2)
self.to_out = LinearNoBias(dim_kv_inner, dim)
# masking related
self.causal = causal
# stability related
self.q_heads_rmsnorm = MultiHeadRMSNorm(dim_head, heads = query_heads)
self.k_heads_rmsnorm = MultiHeadRMSNorm(dim_head, heads = heads)
self.softclamp_value = softclamp_value
def forward(
self,
tokens, # (b n d)
kv_cache = None,
return_kv_cache = False,
mask = None
attend_fn: Callable | None = None,
attend_kwargs: dict = dict(
softclamp_value = None,
causal = False,
mask = None,
scale = None
)
):
tokens, inverse_packed_batch = pack_one(tokens, '* n d')
@ -498,13 +496,9 @@ class Attention(Module):
# attention
out = naive_attend(
q, k, v,
softclamp_value = self.softclamp_value,
scale = self.scale,
causal = self.causal,
mask = mask
)
attend_fn = default(attend_fn, naive_attend)
out = attend_fn(q, k, v, **attend_kwargs)
# merge heads
@ -560,6 +554,7 @@ class VideoTokenizer(Module):
dim_head = 64,
heads = 8,
),
attn_softclamp_value = 50.,
ff_kwargs: dict = dict(),
decoder_pos_mlp_depth = 2,
channels = 3,
@ -594,6 +589,10 @@ class VideoTokenizer(Module):
Rearrange('b t h w (p1 p2 c) -> b c t (h p1) (w p2)', p1 = patch_size, p2 = patch_size),
)
# attention related
self.attn_softclamp_value = attn_softclamp_value
# encoder
encoder_layers = []
@ -706,10 +705,14 @@ class VideoTokenizer(Module):
tokens, inverse_pack_time = pack_one(tokens, 'b * d')
# attend hyper parameters
attend_kwargs = dict(softclamp_value = self.attn_softclamp_value)
# encoder
for attn, ff in self.encoder_layers:
tokens = attn(tokens) + tokens
tokens = attn(tokens, attend_kwargs = attend_kwargs) + tokens
tokens = ff(tokens) + tokens
tokens = self.encoder_norm(tokens)
@ -741,7 +744,7 @@ class VideoTokenizer(Module):
# decoder attention
for attn, ff in self.decoder_layers:
tokens = attn(tokens) + tokens
tokens = attn(tokens, attend_kwargs = attend_kwargs) + tokens
tokens = ff(tokens) + tokens
tokens = self.decoder_norm(tokens)
@ -804,6 +807,7 @@ class DynamicsModel(Module):
dim_head = 64,
heads = 8,
),
attn_softclamp_value = 50.,
ff_kwargs: dict = dict(),
loss_weight_fn: Callable = ramp_weight,
num_future_predictions = 8 # they do multi-token prediction of 8 steps forward
@ -842,13 +846,20 @@ class DynamicsModel(Module):
self.action_learned_embed = Parameter(torch.randn(dim) * 1e-2)
# attention
self.attn_softclamp_value = attn_softclamp_value
# transformer
layers = []
is_time = []
for i in range(depth):
layer_index = i + 1
is_time_block = divisible_by(layer_index, time_block_every)
is_time.append(is_time_block)
rearrange_to_attend = Rearrange('b t s d -> b s t d') if is_time_block else Identity()
rearrange_from_attend = Rearrange('b s t d -> b t s d') if is_time_block else Identity()
@ -856,11 +867,12 @@ class DynamicsModel(Module):
layers.append(ModuleList([
rearrange_to_attend,
rearrange_from_attend,
Attention(dim = dim, causal = is_time_block, **attn_kwargs),
Attention(dim = dim, **attn_kwargs),
SwiGLUFeedforward(dim = dim, **ff_kwargs)
]))
self.layers = ModuleList(layers)
self.is_time = is_time
# to prediction
@ -949,14 +961,28 @@ class DynamicsModel(Module):
# attention
for pre_attn_rearrange, post_attn_rearrange, attn, ff in self.layers:
for (pre_attn_rearrange, post_attn_rearrange, attn, ff), layer_is_time in zip(self.layers, self.is_time):
tokens = pre_attn_rearrange(tokens)
tokens = attn(tokens) + tokens
# when is a axial time attention block, should be causal
attend_kwargs = dict()
if layer_is_time:
attend_kwargs.update(
softclamp_value = self.attn_softclamp_value,
causal = True
)
# attention layer
tokens = attn(tokens, attend_kwargs = attend_kwargs) + tokens
tokens = post_attn_rearrange(tokens)
# feedforward layer
tokens = ff(tokens) + tokens
# unpack