Create custom attention shape for Falcon 7B

awq/modules/fused/block.py

@@ -33,10 +33,20 @@ class FalconDecoderLayer(nn.Module):
         super().__init__()
         self.n_heads = n_heads
         self.hidden_size = hidden_size
-        # TODO: Falcon has ALiBi implemented but which model uses it?
-        self.attn = QuantAttentionFused(hidden_size, self.n_heads, qkv_layer, o_proj, dev=dev, max_seq_len=max_seq_len, use_alibi=False).to(dev)
         self.new_decoder_arch = new_decoder_arch
         
+        if new_decoder_arch:
+            attention_shapes = None
+        else:
+            attention_shapes = self._get_attention_shapes(1, n_heads, max_seq_len, self.hidden_size // n_heads)
+        
+        # TODO: Falcon has ALiBi implemented but which model uses it?
+        self.attn = QuantAttentionFused(
+            hidden_size, self.n_heads, qkv_layer, o_proj, 
+            dev=dev, max_seq_len=max_seq_len, use_alibi=False,
+            attention_shapes=attention_shapes
+        ).to(dev)
+        
         if new_decoder_arch:
             self.ln_attn = ln_attn # before attention
             self.ln_mlp = ln_mlp # before mlp
@@ -45,6 +55,26 @@ class FalconDecoderLayer(nn.Module):
         
         self.mlp = mlp
     
+    def _get_attention_shapes(self, batch_size, n_heads, max_seq_len, head_dim):
+        self.attention_shapes = {
+            # following fastertransformer definition
+            "cache_v": (batch_size, 1, max_seq_len, head_dim,),
+            # 8: pack 8 fp16 in FT, if fp32 then use 4
+            "cache_k": (batch_size, 1, head_dim // 8, max_seq_len, 8,),
+            "xqkv_view": (n_heads+2, head_dim),
+            "xq_slice": lambda xqkv: xqkv[:, :, :-2],
+            "xk_slice": lambda xqkv: xqkv[:, :, [-2]],
+            "xv_slice": lambda xqkv: xqkv[:, :, [-1]],
+            "xk_reshape": (1, head_dim // 8, 8),
+            "xk_view": (1, head_dim),
+            "xv_view": (1, head_dim),
+            "single_xq_view": (n_heads, head_dim),
+            "single_xk_view": (1, head_dim),
+            "single_xv_view": (1, head_dim)
+        }
+
+        return self.attention_shapes
+
     def forward(
         self, hidden_states, past_key_value, attn_bias=None, attention_mask=None, is_causal=None
     ):