diff --git a/python/infinilm/llm/scheduler.py b/python/infinilm/llm/scheduler.py
index c10b55f2f..085837658 100644
--- a/python/infinilm/llm/scheduler.py
+++ b/python/infinilm/llm/scheduler.py
@@ -133,6 +133,7 @@ def schedule(self) -> Optional[SchedulerOutput]:
         is_prefill = False
         current_num_batched_tokens = 0
         current_prefill_extra_blocks = 0
+        running_required_blocks = None
 
         # Process Waiting queue (prefill phase)
         while (
@@ -199,10 +200,18 @@ def schedule(self) -> Optional[SchedulerOutput]:
                         deferred_requests.append(req)
                         break
 
+                if running_required_blocks is None and (
+                    self.mamba_cache_manager is None
+                    or req.mamba_cache_index is not None
+                    or self.mamba_cache_manager.can_allocate()
+                ):
+                    # Running requests do not advance during this prefill loop.
+                    running_required_blocks = self._get_running_required_blocks()
                 if not self.can_accept_request(
                     req,
                     num_local_computed_tokens,
                     current_prefill_extra_blocks,
+                    running_required_blocks=running_required_blocks,
                 ):
                     logger.warning(
                         "Insufficient KV cache blocks for request %s, deferring.",
@@ -450,12 +459,31 @@ def complete_requests(self, requests: List[InferenceRequest]):
                 # Still running, put back in running queue
                 self.running_queue.sync_q.put(req)
 
+    def _get_running_required_blocks(self) -> int:
+        """Sum decode reservations while preserving running queue order."""
+        total_required_blocks = 0
+        running_queue_size = self.running_queue.sync_q.qsize()
+        for _ in range(running_queue_size):
+            req = self.running_queue.sync_q.get()
+            remaining_tokens = (
+                req.sampling_params.max_tokens - req.get_num_generated_tokens()
+            )
+            num_blocks_needed = (
+                remaining_tokens + self.block_size - 1
+            ) // self.block_size
+            total_required_blocks += num_blocks_needed
+            self.running_queue.sync_q.put(req)
+        return total_required_blocks
+
     def can_accept_request(
         self,
         request: InferenceRequest,
         num_local_computed_tokens: int,
         current_prefill_extra_blocks: int = 0,
+        *,
+        running_required_blocks: int | None = None,
     ) -> bool:
+        """Check capacity, optionally reusing this schedule's running reservations."""
         if (
             self.mamba_cache_manager is not None
             and request.mamba_cache_index is None
@@ -463,20 +491,11 @@ def can_accept_request(
         ):
             return False
 
-        total_required_blocks = 0
-
-        # Calculate blocks needed for running requests
-        running_queue_size = self.running_queue.sync_q.qsize()
-        for _ in range(running_queue_size):
-            req = self.running_queue.sync_q.get()
-            remaining_tokens = (
-                req.sampling_params.max_tokens - req.get_num_generated_tokens()
-            )
-            num_blocks_needed = (
-                remaining_tokens + self.block_size - 1
-            ) // self.block_size
-            total_required_blocks += num_blocks_needed
-            self.running_queue.sync_q.put(req)
+        total_required_blocks = (
+            self._get_running_required_blocks()
+            if running_required_blocks is None
+            else running_required_blocks
+        )
 
         # Calculate blocks needed for the new request
         total_length = request.get_prompt_length() - num_local_computed_tokens