Decouple kv (#679)

python/sglang/srt/layers/radix_attention.py

@@ -99,7 +99,7 @@ class RadixAttention(nn.Module):
         else:
             o2, s2 = input_metadata.flashinfer_prefill_wrapper_paged.forward_return_lse(
                 q.contiguous().view(-1, self.tp_q_head_num, self.head_dim),
-                input_metadata.token_to_kv_pool.kv_data[self.layer_id],
+                input_metadata.token_to_kv_pool.get_kv_buffer(self.layer_id),
                 causal=False,
                 sm_scale=self.scaling,
                 logits_soft_cap=self.logit_cap,
@@ -119,7 +119,7 @@ class RadixAttention(nn.Module):
 
         o = input_metadata.flashinfer_decode_wrapper.forward(
             q.contiguous().view(-1, self.tp_q_head_num, self.head_dim),
-            input_metadata.token_to_kv_pool.kv_data[self.layer_id],
+            input_metadata.token_to_kv_pool.get_kv_buffer(self.layer_id),
             sm_scale=self.scaling,
             logits_soft_cap=self.logit_cap,
         )
@@ -136,33 +136,7 @@ class RadixAttention(nn.Module):
             return self.decode_forward(q, k, v, input_metadata)
 
     def store_kv_cache(self, cache_k, cache_v, input_metadata: InputMetadata):
-        kv_cache = input_metadata.token_to_kv_pool.kv_data[self.layer_id]
+        k_cache = input_metadata.token_to_kv_pool.get_key_buffer(self.layer_id)
-        _store_kv_cache(cache_k, cache_v, kv_cache, input_metadata.out_cache_loc)
+        v_cache = input_metadata.token_to_kv_pool.get_value_buffer(self.layer_id)
-
+        k_cache[input_metadata.out_cache_loc] = cache_k
-
+        v_cache[input_metadata.out_cache_loc] = cache_v
-try:
-
-    @torch.library.custom_op("mylib::store_kv_cache", mutates_args={"kv_cache"})
-    def _store_kv_cache(
-        k: torch.Tensor,
-        v: torch.Tensor,
-        kv_cache: torch.Tensor,
-        cache_loc: torch.Tensor,
-    ) -> None:
-        kv_cache[cache_loc, 0] = k
-        kv_cache[cache_loc, 1] = v
-
-    @_store_kv_cache.register_fake
-    def _(k, v, kv_cache, cache_loc):
-        pass
-
-except:
-
-    def _store_kv_cache(
-        k: torch.Tensor,
-        v: torch.Tensor,
-        kv_cache: torch.Tensor,
-        cache_loc: torch.Tensor,
-    ) -> None:
-        kv_cache[cache_loc, 0] = k
-        kv_cache[cache_loc, 1] = v

python/sglang/srt/memory_pool.py

@@ -57,9 +57,13 @@ class TokenToKVPool:
         # We also add one slot. This slot is used for writing dummy output from padded tokens.
         self.mem_state = torch.ones((self.size + 1,), dtype=torch.bool, device="cuda")
 
-        # [size, key/value, head_num, head_dim] for each layer
+        # [size, head_num, head_dim] for each layer
-        self.kv_data = [
+        self.k_buffer = [
-            torch.empty((size + 1, 2, head_num, head_dim), dtype=dtype, device="cuda")
+            torch.empty((size + 1, head_num, head_dim), dtype=dtype, device="cuda")
+            for _ in range(layer_num)
+        ]
+        self.v_buffer = [
+            torch.empty((size + 1, head_num, head_dim), dtype=dtype, device="cuda")
             for _ in range(layer_num)
         ]
 
@@ -71,10 +75,13 @@ class TokenToKVPool:
         self.clear()
 
     def get_key_buffer(self, layer_id: int):
-        return self.kv_data[layer_id][:, 0]
+        return self.k_buffer[layer_id]
 
     def get_value_buffer(self, layer_id: int):
-        return self.kv_data[layer_id][:, 1]
+        return self.v_buffer[layer_id]
+
+    def get_kv_buffer(self, layer_id: int):
+        return self.k_buffer[layer_id], self.v_buffer[layer_id]
 
     def available_size(self):
         return self.can_use_mem_size + len(self.prefetch_buffer)

python/sglang/srt/server.py

@@ -182,7 +182,7 @@ def launch_server(
     if not server_args.disable_flashinfer:
         assert_pkg_version(
             "flashinfer",
-            "0.1.0",
+            "0.1.1",
             "Please uninstall the old version and "
             "reinstall the latest version by following the instructions "
             "at https://docs.flashinfer.ai/installation.html.",