diff --git a/cacheflow/models/input_metadata.py b/cacheflow/models/input_metadata.py
index 8f50fbfb..5963e67e 100644
--- a/cacheflow/models/input_metadata.py
+++ b/cacheflow/models/input_metadata.py
@@ -7,12 +7,14 @@ class InputMetadata:
 
     def __init__(
         self,
+        seq_ids: List[int],
         prompt_lens: List[int],
         slot_mapping: torch.Tensor,
         context_lens: torch.Tensor,
         max_context_len: int,
         block_tables: torch.Tensor,
     ) -> None:
+        self.seq_ids = seq_ids
         self.prompt_lens = prompt_lens
         self.slot_mapping = slot_mapping
         self.context_lens = context_lens
@@ -23,3 +25,4 @@ class InputMetadata:
         self.num_generation_tokens = context_lens.shape[0]
         self.max_num_blocks_per_seq = block_tables.shape[1]
         assert self.num_generation_tokens == block_tables.shape[0]
+        assert self.num_prompts + self.num_generation_tokens == len(seq_ids)
diff --git a/cacheflow/worker/worker.py b/cacheflow/worker/worker.py
index 1d67c3ef..52a84128 100644
--- a/cacheflow/worker/worker.py
+++ b/cacheflow/worker/worker.py
@@ -1,4 +1,4 @@
-from typing import Dict, List, Tuple
+from typing import Dict, List, Tuple, Union
 
 import torch
 
@@ -120,6 +120,7 @@ class Worker:
             padded_block_tables, dtype=int, device=self.device)
 
         input_metadata = InputMetadata(
+            seq_ids=prompt_seq_ids + generation_seq_ids,
             prompt_lens=prompt_lens,
             slot_mapping=slot_mapping_tensor,
             context_lens=context_lens_tensor,
@@ -128,7 +129,6 @@ class Worker:
         )
         return tokens_tensor, positions_tensor, input_metadata
 
-
     @torch.inference_mode()
     def execute_stage(
         self,
@@ -139,7 +139,7 @@ class Worker:
         blocks_to_swap_in: Dict[int, int],
         blocks_to_swap_out: Dict[int, int],
         blocks_to_copy: Dict[int, int],
-    ) -> torch.Tensor:
+    ) -> Union[torch.Tensor, Dict[int, Tuple[int, int]]]:
         # Issue cache operations.
         command_issued = False
         if blocks_to_swap_in: