[FlashInfer] Cache hyper params in metadata builder (#23732)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

vllm/v1/attention/backends/flashinfer.py

@@ -214,6 +214,10 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
         # TODO: discard this for trtllm-gen backend
         self.global_hyperparameters = infer_global_hyperparameters(
             get_per_layer_parameters(vllm_config, layer_names, FlashInferImpl))
+        self.sm_scale = self.global_hyperparameters.sm_scale
+        self.window_left = self.global_hyperparameters.window_left
+        self.logits_soft_cap = self.global_hyperparameters.logits_soft_cap
+        self.has_sinks = self.global_hyperparameters.has_sinks
 
         # Preparing persistent buffers (device-side)
         self.paged_kv_indptr = torch.zeros(max_num_reqs + 1,
@@ -381,8 +385,6 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
         )
 
         # Check if any layer uses sinks (requires TRTLLM attention)
-        has_sinks = self.global_hyperparameters.has_sinks
-
         prefill_use_trtllm = use_trtllm_attention(self.num_qo_heads,
                                                   self.num_kv_heads,
                                                   num_prefill_tokens,
@@ -390,7 +392,7 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
                                                   self.cache_dtype,
                                                   self.q_data_type,
                                                   is_prefill=True,
-                                                  has_sinks=has_sinks)
+                                                  has_sinks=self.has_sinks)
         decode_use_trtllm = use_trtllm_attention(self.num_qo_heads,
                                                  self.num_kv_heads,
                                                  num_decode_tokens,
@@ -398,7 +400,7 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
                                                  self.cache_dtype,
                                                  self.q_data_type,
                                                  is_prefill=False,
-                                                 has_sinks=has_sinks)
+                                                 has_sinks=self.has_sinks)
 
         attn_metadata = FlashInferMetadata(
             num_actual_tokens=num_actual_tokens,
@@ -433,9 +435,9 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
                 self.head_dim,
                 self.page_size,
                 causal=True,
-                sm_scale=self.global_hyperparameters.sm_scale,
-                window_left=self.global_hyperparameters.window_left,
-                logits_soft_cap=self.global_hyperparameters.logits_soft_cap,
+                sm_scale=self.sm_scale,
+                window_left=self.window_left,
+                logits_soft_cap=self.logits_soft_cap,
                 q_data_type=self.q_data_type,
                 kv_data_type=self.kv_cache_dtype,
             )
@@ -472,10 +474,9 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
                         self.head_dim,
                         self.page_size,
                         causal=True,
-                        sm_scale=self.global_hyperparameters.sm_scale,
-                        window_left=self.global_hyperparameters.window_left,
-                        logits_soft_cap=self.global_hyperparameters.
-                        logits_soft_cap,
+                        sm_scale=self.sm_scale,
+                        window_left=self.window_left,
+                        logits_soft_cap=self.logits_soft_cap,
                         q_data_type=self.q_data_type,
                         kv_data_type=self.kv_cache_dtype,
                     )
@@ -525,10 +526,9 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
                         self.page_size,
                         # Disable flashinfer's pos encoding and use vllm's rope.
                         pos_encoding_mode="NONE",
-                        sm_scale=self.global_hyperparameters.sm_scale,
-                        window_left=self.global_hyperparameters.window_left,
-                        logits_soft_cap=self.global_hyperparameters.
-                        logits_soft_cap,
+                        sm_scale=self.sm_scale,
+                        window_left=self.window_left,
+                        logits_soft_cap=self.logits_soft_cap,
                         q_data_type=self.q_data_type,
                         kv_data_type=self.kv_cache_dtype,
                     )