Remove learnable offset, use relu instead.

This commit is contained in:
Daniel Povey 2022-02-07 12:14:48 +08:00
parent 48a764eccf
commit a859dcb205

View File

@ -440,19 +440,8 @@ class RelPositionMultiheadAttention(nn.Module):
), "embed_dim must be divisible by num_heads"
self.in_proj = nn.Linear(embed_dim, 3 * embed_dim, bias=True)
self.in_proj_floor_scale = 10.0 # so it learns fast enough..
with torch.no_grad():
in_proj_floor = torch.Tensor(3 * embed_dim)
# key and query get a floor value quite close to zero.
in_proj_floor[:2*embed_dim] = -0.2 / self.in_proj_floor_scale
# value gets very low floor, may be close to having no effectc.
in_proj_floor[2*embed_dim:] = -1.5 / self.in_proj_floor_scale
self.in_proj_floor = nn.Parameter(in_proj_floor)
self.out_proj = nn.Linear(embed_dim, embed_dim, bias=True)
# linear transformation for positional encoding.
self.linear_pos = nn.Linear(embed_dim, embed_dim, bias=False)
# these two learnable bias are used in matrix c and matrix d
@ -537,7 +526,6 @@ class RelPositionMultiheadAttention(nn.Module):
key_padding_mask=key_padding_mask,
need_weights=need_weights,
attn_mask=attn_mask,
in_proj_floor=self.in_proj_floor*self.in_proj_floor_scale
)
def rel_shift(self, x: Tensor) -> Tensor:
@ -582,7 +570,6 @@ class RelPositionMultiheadAttention(nn.Module):
key_padding_mask: Optional[Tensor] = None,
need_weights: bool = True,
attn_mask: Optional[Tensor] = None,
in_proj_floor: Optional[Tensor] = None,
) -> Tuple[Tensor, Optional[Tensor]]:
r"""
Args:
@ -642,12 +629,7 @@ class RelPositionMultiheadAttention(nn.Module):
if torch.equal(query, key) and torch.equal(key, value):
# self-attention
_qkv = nn.functional.linear(
query, in_proj_weight, in_proj_bias
)
if in_proj_floor is not None:
_qkv = torch.maximum(_qkv, in_proj_floor)
q, k, v = _qkv.chunk(3, dim=-1)
q, k, v = nn.functional.linear(query, in_proj_weight, in_proj_bias).relu().chunk(3, dim=-1)
elif torch.equal(key, value):
# encoder-decoder attention
@ -658,10 +640,7 @@ class RelPositionMultiheadAttention(nn.Module):
_w = in_proj_weight[_start:_end, :]
if _b is not None:
_b = _b[_start:_end]
q = nn.functional.linear(query, _w, _b)
if in_proj_floor is not None:
_f = in_proj_floor[_start:_end]
q = torch.maximum(q, _f)
q = nn.functional.linear(query, _w, _b).relu()
# This is inline in_proj function with in_proj_weight and in_proj_bias
_b = in_proj_bias
@ -670,11 +649,7 @@ class RelPositionMultiheadAttention(nn.Module):
_w = in_proj_weight[_start:, :]
if _b is not None:
_b = _b[_start:]
_kv = nn.functional.linear(key, _w, _b)
if in_proj_floor is not None:
_f = in_proj_floor[_start:_end]
_kv = torch.maximum(_kv, _f)
k, v = _kv.chunk(2, dim=-1)
k, v = nn.functional.linear(key, _w, _b).relu().chunk(2, dim=-1)
else:
# This is inline in_proj function with in_proj_weight and in_proj_bias
@ -684,10 +659,7 @@ class RelPositionMultiheadAttention(nn.Module):
_w = in_proj_weight[_start:_end, :]
if _b is not None:
_b = _b[_start:_end]
q = nn.functional.linear(query, _w, _b)
if in_proj_floor is not None:
_f = in_proj_floor[_start:_end]
q = torch.maximum(q, _f)
q = nn.functional.linear(query, _w, _b).relu()
# This is inline in_proj function with in_proj_weight and in_proj_bias
@ -697,10 +669,7 @@ class RelPositionMultiheadAttention(nn.Module):
_w = in_proj_weight[_start:_end, :]
if _b is not None:
_b = _b[_start:_end]
k = nn.functional.linear(key, _w, _b)
if in_proj_floor is not None:
_f = in_proj_floor[_start:_end]
k = torch.maximum(k, _f)
k = nn.functional.linear(key, _w, _b).relu()
# This is inline in_proj function with in_proj_weight and in_proj_bias
_b = in_proj_bias
@ -709,10 +678,7 @@ class RelPositionMultiheadAttention(nn.Module):
_w = in_proj_weight[_start:, :]
if _b is not None:
_b = _b[_start:]
v = nn.functional.linear(value, _w, _b)
if in_proj_floor is not None:
_f = in_proj_floor[_start:_end]
v = torch.maximum(v, _f)
v = nn.functional.linear(value, _w, _b).relu()
if attn_mask is not None: