[fix] fp16 attention overflow

master
jingyaogong 2026-09-20 20:39:51 +08:00
parent fa36e4861d
commit dacc687889
1 changed files with 2 additions and 2 deletions

View File

@ -125,10 +125,10 @@ class Attention(nn.Module):
if self.flash and (seq_len > 1) and (not self.is_causal or past_key_value is None) and (attention_mask is None or torch.all(attention_mask == 1)): if self.flash and (seq_len > 1) and (not self.is_causal or past_key_value is None) and (attention_mask is None or torch.all(attention_mask == 1)):
output = F.scaled_dot_product_attention(xq, xk, xv, dropout_p=self.dropout if self.training else 0.0, is_causal=self.is_causal) output = F.scaled_dot_product_attention(xq, xk, xv, dropout_p=self.dropout if self.training else 0.0, is_causal=self.is_causal)
else: else:
scores = (xq @ xk.transpose(-2, -1)) / math.sqrt(self.head_dim) scores = (xq @ xk.transpose(-2, -1)).float() / math.sqrt(self.head_dim)
if self.is_causal: scores[:, :, :, -seq_len:] += torch.full((seq_len, seq_len), float("-inf"), device=scores.device).triu(1) if self.is_causal: scores[:, :, :, -seq_len:] += torch.full((seq_len, seq_len), float("-inf"), device=scores.device).triu(1)
if attention_mask is not None: scores += (1.0 - attention_mask.unsqueeze(1).unsqueeze(2)) * -1e9 if attention_mask is not None: scores += (1.0 - attention_mask.unsqueeze(1).unsqueeze(2)) * -1e9
output = self.attn_dropout(F.softmax(scores.float(), dim=-1).type_as(xq)) @ xv output = self.attn_dropout(F.softmax(scores, dim=-1).type_as(xq)) @ xv
output = output.transpose(1, 2).reshape(bsz, seq_len, -1) output = output.transpose(1, 2).reshape(bsz, seq_len, -1)
output = self.resid_dropout(self.o_proj(output)) output = self.resid_dropout(self.o_proj(output))
return output, past_kv return output, past_kv