Fix swa input length limitation (#22597)

python/sglang/srt/managers/schedule_policy.py

@@ -428,6 +428,8 @@ class PrefillAdder:
         )
         self.is_hybrid_ssm_cache = self.tree_cache.supports_mamba()
 
+        self.rem_swa_token_offset = 0
+
         self.priority_scheduling_preemption_threshold = (
             priority_scheduling_preemption_threshold
         )
@@ -456,11 +458,9 @@ class PrefillAdder:
     @property
     def rem_total_tokens(self):
         if self.is_hybrid_swa:
-            available_and_evictable = min(
+            available_and_evictable = (
                 self.token_to_kv_pool_allocator.full_available_size()
-                + self.tree_cache.full_evictable_size(),
-                self.token_to_kv_pool_allocator.swa_available_size()
-                + self.tree_cache.swa_evictable_size(),
+                + self.tree_cache.full_evictable_size()
             )
         elif self.is_hybrid_ssm_cache:
             available_and_evictable = (
@@ -474,14 +474,20 @@ class PrefillAdder:
             )
         return available_and_evictable - self.rem_total_token_offset
 
+    @property
+    def rem_swa_tokens(self):
+        return (
+            self.token_to_kv_pool_allocator.swa_available_size()
+            + self.tree_cache.swa_evictable_size()
+            - self.rem_swa_token_offset
+        )
+
     @property
     def cur_rem_tokens(self):
         if self.is_hybrid_swa:
-            available_and_evictable = min(
+            available_and_evictable = (
                 self.token_to_kv_pool_allocator.full_available_size()
-                + self.tree_cache.full_evictable_size(),
-                self.token_to_kv_pool_allocator.swa_available_size()
-                + self.tree_cache.swa_evictable_size(),
+                + self.tree_cache.full_evictable_size()
             )
         elif self.is_hybrid_ssm_cache:
             available_and_evictable = (
@@ -496,11 +502,31 @@ class PrefillAdder:
 
         return available_and_evictable - self.cur_rem_token_offset
 
+    def _swa_budget_for_req(self, extend_input_len: int) -> int:
+        """SWA pool budget per request. Only valid when is_hybrid_swa is True.
+
+        With chunked prefill + overlap scheduler, the peak SWA occupancy is:
+          chunk N (running, not yet in tree) + sliding window (locked in tree)
+          + chunk N+1 (new allocation)
+        Since chunk N and locked tokens are already excluded from
+        swa_available + swa_evictable, the budget only needs to cover the
+        chunk N+1 allocation. We floor at sliding_window_size to reserve
+        room for the decode phase.
+        """
+        if self.rem_chunk_tokens is not None:
+            alloc = min(extend_input_len, self.rem_chunk_tokens)
+        else:
+            alloc = extend_input_len
+        return max(alloc, self.tree_cache.sliding_window_size) + self.page_size
+
     def ceil_paged_tokens(self, tokens: int) -> int:
         return -(-tokens // self.page_size) * self.page_size
 
     def budget_state(self):
-        if self.rem_total_tokens <= 0 or self.cur_rem_tokens <= 0:
+        no_token = self.rem_total_tokens <= 0 or self.cur_rem_tokens <= 0
+        if not no_token and self.is_hybrid_swa:
+            no_token = self.rem_swa_tokens <= 0
+        if no_token:
             return AddReqResult.NO_TOKEN
 
         if self.rem_input_tokens <= 0:
@@ -527,6 +553,9 @@ class PrefillAdder:
         self.cur_rem_token_offset += extend_input_len + page_overhead
         self.rem_input_tokens -= extend_input_len
 
+        if self.is_hybrid_swa:
+            self.rem_swa_token_offset += self._swa_budget_for_req(extend_input_len)
+
         if self.dllm_config is not None:
             self.rem_dllm_tokens -= extend_input_len
         elif self.rem_chunk_tokens is not None:
@@ -601,6 +630,8 @@ class PrefillAdder:
             _rem_tokens = self._get_dllm_remain_tokens()
         else:
             _rem_tokens = min(self.rem_chunk_tokens, int(self.rem_total_tokens))
+            if self.is_hybrid_swa:
+                _rem_tokens = min(_rem_tokens, int(self.rem_swa_tokens))
             # The chunked_req must be added to the list; otherwise, it will cause a memory leak.
             # Therefore, in certain cases where _rem_tokens <= 0, it should be replaced with rem_chunk_tokens.
             if _rem_tokens <= 0:
@@ -639,11 +670,12 @@ class PrefillAdder:
                 self.tree_cache.dec_lock_ref(last_node)
 
     def add_one_req_ignore_eos(self, req: Req):
-        # Early exit if no enough tokens for the input tokens
-        if self.ceil_paged_tokens(req.extend_input_len) > min(
-            self.cur_rem_tokens, self.rem_total_tokens
-        ):
+        paged_input = self.ceil_paged_tokens(req.extend_input_len)
+        if paged_input > min(self.cur_rem_tokens, self.rem_total_tokens):
             return AddReqResult.NO_TOKEN
+        if self.is_hybrid_swa:
+            if self._swa_budget_for_req(req.extend_input_len) > self.rem_swa_tokens:
+                return AddReqResult.NO_TOKEN
 
         def add_req_state(r, insert_sort=False):
             new_token_ratio = (
@@ -756,14 +788,11 @@ class PrefillAdder:
         # _update_prefill_budget already accounts for this in the deduction.
         # Without this, admission is more optimistic than the actual budget
         # deduction, allowing over-admission when the pool is nearly full.
-        total_tokens = (
-            req.extend_input_len
-            + min(
-                max(req.sampling_params.max_new_tokens - len(req.output_ids), 0),
-                CLIP_MAX_NEW_TOKENS,
-            )
-            + self.page_size
+        max_new = min(
+            max(req.sampling_params.max_new_tokens - len(req.output_ids), 0),
+            CLIP_MAX_NEW_TOKENS,
         )
+        total_tokens = req.extend_input_len + max_new + self.page_size
 
         # adjusting the input_tokens based on host_hit_length and page_size
         real_input_tokens = req.extend_input_len - req.host_hit_length
@@ -773,6 +802,11 @@ class PrefillAdder:
         if total_tokens >= self.rem_total_tokens:
             return AddReqResult.NO_TOKEN
 
+        if self.is_hybrid_swa:
+            swa_needed = self._swa_budget_for_req(req.extend_input_len)
+            if swa_needed >= self.rem_swa_tokens:
+                return AddReqResult.NO_TOKEN
+
         if real_input_tokens >= self.rem_input_tokens and len(self.can_run_list) != 0:
             return AddReqResult.OTHER
 
@@ -781,6 +815,11 @@ class PrefillAdder:
             if total_tokens >= self.rem_total_tokens:
                 return AddReqResult.NO_TOKEN
 
+            if self.is_hybrid_swa:
+                swa_needed = self._swa_budget_for_req(req.extend_input_len)
+                if swa_needed >= self.rem_swa_tokens:
+                    return AddReqResult.NO_TOKEN
+
             if req.host_hit_length > 0:
                 new_indices, req.last_node = self.tree_cache.init_load_back(
                     InitLoadBackParams(

python/sglang/srt/model_executor/model_runner.py

@@ -1961,7 +1961,7 @@ class ModelRunner(ModelRunnerKVCacheMixin):
     def max_token_pool_size(self):
         """Return the max token pool size considering hybrid swa settings."""
         if self.is_hybrid_swa:
-            return min(self.swa_max_total_num_tokens, self.max_total_num_tokens)
+            return self.full_max_total_num_tokens
         else:
             return self.max_total_num_tokens