[V1][Prefix Cache] Move the logic of num_computed_tokens into KVCacheManager (#12003)

tests/v1/core/test_prefix_caching.py

@@ -49,9 +49,10 @@ def test_prefill():
     unique_token_ids = [3] * 7
     all_token_ids = common_token_ids + unique_token_ids
     req0 = make_request("0", all_token_ids)
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
     assert len(req0.kv_block_hashes) == 3
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req0, 55, computed_blocks)
     assert [b.block_id for b in blocks] == [0, 1, 2, 3, 4]
 
@@ -73,9 +74,10 @@ def test_prefill():
     # Incomplete 1 block (5 tokens)
     unique_token_ids = [3] * 5
     req1 = make_request("1", common_token_ids + unique_token_ids)
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert len(req1.kv_block_hashes) == 3
     assert [b.block_id for b in computed_blocks] == [0, 1, 2]
+    assert num_computed_tokens == 3 * 16
     num_new_tokens = 53 - 3 * 16
     blocks = manager.allocate_slots(req1, num_new_tokens, computed_blocks)
     assert [b.block_id for b in blocks] == [5, 6]
@@ -91,7 +93,7 @@ def test_prefill():
     # All blocks should be available.
     assert manager.free_block_queue.num_free_blocks == 10
     # The order should be
-    # [unallocated (7, 8)]
+    # [unallocated (7, 8, 9)]
     # [unique_req0 (4, 3)]
     # [unique_req1 (6, 5)]
     # [common (2, 1, 0)]
@@ -103,9 +105,10 @@ def test_prefill():
     # Incomplete 1 block (6 tokens)
     unique_token_ids = [3] * 6
     req2 = make_request("2", common_token_ids + unique_token_ids)
-    computed_blocks = manager.get_computed_blocks(req2)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert len(req2.kv_block_hashes) == 3
     assert [b.block_id for b in computed_blocks] == [0, 1, 2]
+    assert num_computed_tokens == 3 * 16
     num_new_tokens = 53 - 3 * 16
     blocks = manager.allocate_slots(req2, num_new_tokens, computed_blocks)
     assert [b.block_id for b in blocks] == [7, 8]
@@ -123,8 +126,9 @@ def test_prefill():
 
     # Cache miss and eviction.
     req3 = make_request("3", [99] * (16 * 9))
-    computed_blocks = manager.get_computed_blocks(req3)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req3)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req3, 16 * 9, computed_blocks)
     # This block ID order also checks the eviction order.
     assert [b.block_id for b in blocks] == [9, 4, 3, 6, 5, 8, 7, 2, 1, 0]
@@ -150,8 +154,9 @@ def test_decode():
     # Incomplete 1 block (7 tokens)
     unique_token_ids = [3] * 7
     req0 = make_request("0", common_token_ids + unique_token_ids)
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req0, 55, computed_blocks)
     assert [b.block_id for b in blocks] == [0, 1, 2, 3, 4]
 
@@ -197,16 +202,18 @@ def test_evict():
 
     last_token_id = 5 * 16 + 7
     req0 = make_request("0", list(range(last_token_id)))
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req0, 5 * 16 + 7, computed_blocks)
     assert len(blocks) == 7  # 5 full + 1 partial + 1 preallocated
 
     # 3 blocks.
     req1 = make_request("1", list(range(last_token_id,
                                         last_token_id + 3 * 16)))
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req1, 3 * 16, computed_blocks)
     assert len(blocks) == 3  # 3 full blocks
     last_token_id += 3 * 16
@@ -222,8 +229,9 @@ def test_evict():
 
     # Touch the first 2 blocks.
     req2 = make_request("2", list(range(2 * 16 + 3)))
-    computed_blocks = manager.get_computed_blocks(req2)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert [b.block_id for b in computed_blocks] == [0, 1]
+    assert num_computed_tokens == 2 * 16
     blocks = manager.allocate_slots(req2, 3, computed_blocks)
     assert [b.block_id for b in blocks] == [6, 5]
     assert manager.free_block_queue.num_free_blocks == 6
@@ -247,8 +255,9 @@ def test_hash_block_correct_reuse():
     # Allocate 1 block and cache it.
     num_tokens = block_size * 1
     req = make_request("0", list(range(num_tokens)))
-    computed_blocks = manager.get_computed_blocks(req)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req, num_tokens, computed_blocks)
     assert len(blocks) == 1
 
@@ -258,8 +267,9 @@ def test_hash_block_correct_reuse():
     # Allocate a new block that's not full, make sure hash info on the
     # block is cleared.
     req = make_request("1", list(range(num_tokens - 1)))
-    computed_blocks = manager.get_computed_blocks(req)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req, num_tokens - 1, computed_blocks)
     assert len(blocks) == 1
 
@@ -284,16 +294,18 @@ def test_computed_blocks_not_evicted():
     # Allocate a block and cache it.
     num_tokens = block_size * 1
     req0 = make_request("0", list(range(num_tokens)))
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req0, num_tokens, computed_blocks)
     assert len(blocks) == 1
     assert blocks[0].block_id == 0
 
     # Allocate another block.
     req1 = make_request("1", list(range(num_tokens, num_tokens * 2)))
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req1, num_tokens, computed_blocks)
     assert len(blocks) == 1
     assert blocks[0].block_id == 1
@@ -305,9 +317,10 @@ def test_computed_blocks_not_evicted():
     # Now if we have a cache hit on the first block, we should evict the second
     # cached block rather than the first one.
     req2 = make_request("2", list(range(num_tokens * 2)))
-    computed_blocks = manager.get_computed_blocks(req2)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert len(computed_blocks) == 1
     assert computed_blocks[0].block_id == 0
+    assert num_computed_tokens == block_size
 
     blocks = manager.allocate_slots(req2, num_tokens * 2 - num_tokens,
                                     computed_blocks)
@@ -331,8 +344,9 @@ def test_basic_prefix_caching_disabled():
 
     req1 = make_request("1", list(range(10)))  # 2 blocks and some more
 
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req1, 10, computed_blocks)
     assert len(blocks) == 3
 
@@ -341,15 +355,17 @@ def test_basic_prefix_caching_disabled():
 
     # No caching.
     req2 = make_request("2", list(range(16)))  # shared prefix
-    computed_blocks = manager.get_computed_blocks(req2)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req2, 16, computed_blocks)
     assert len(blocks) == 4
 
     # New requests should not have any blocks.
     req3 = make_request("3", list(range(4)))
-    computed_blocks = manager.get_computed_blocks(req3)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req3)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     blocks = manager.allocate_slots(req3, 4, computed_blocks)
     assert not blocks
 
@@ -371,8 +387,9 @@ def test_preallocate_blocks(num_preallocate_tokens: int, block_size: int):
     num_preallocated_blocks = cdiv(num_preallocate_tokens, block_size)
 
     req = make_request("0", list(range(block_size * 30)))
-    computed_blocks = manager.get_computed_blocks(req)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     # Just ask for 1 block.
     blocks = manager.allocate_slots(req, block_size, computed_blocks)
     req.num_computed_tokens = block_size
@@ -469,10 +486,11 @@ def test_mm_prefix_caching():
                         all_token_ids,
                         mm_positions=mm_positions,
                         mm_hashes=mm_hashes)
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
 
     # Completed block should have hashes with extra keys.
     assert not computed_blocks
+    assert num_computed_tokens == 0
     assert len(req0.kv_block_hashes) == 3
     assert req0.kv_block_hashes[0].extra_keys == ("aaa", )
     assert req0.kv_block_hashes[1].extra_keys == ("aaa", "bbb")
@@ -503,8 +521,9 @@ def test_mm_prefix_caching():
                         all_token_ids,
                         mm_positions=mm_positions,
                         mm_hashes=mm_hashes)
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert len(computed_blocks) == 3
+    assert num_computed_tokens == 3 * 16
 
 
 def test_prefill_not_enough_free_blocks_with_computed_blocks():
@@ -527,15 +546,17 @@ def test_prefill_not_enough_free_blocks_with_computed_blocks():
     # | Common-0 | Common-1 | Common-2 | ... |
     common_token_ids = [i for i in range(3) for _ in range(16)]
     req0 = make_request("0", common_token_ids)
-    computed_blocks = manager.get_computed_blocks(req0)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req0)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     manager.allocate_slots(req0, 48, computed_blocks)
     block_part0 = manager.req_to_blocks[req0.request_id]
 
     # | Common-0 | Common-1 | Common-2 | Req1-3 | Req1-4 | Req1-5 | ... |
     req1 = make_request("1", common_token_ids * 2)
-    computed_blocks = manager.get_computed_blocks(req1)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert computed_blocks == block_part0
+    assert num_computed_tokens == 3 * 16
     manager.allocate_slots(req1, 48, computed_blocks)
     block_part1 = manager.req_to_blocks[req1.request_id]
     # | Common-0 | Common-1 | Common-2 | Req1-3 (F) | Req1-4 (F) |
@@ -547,8 +568,9 @@ def test_prefill_not_enough_free_blocks_with_computed_blocks():
     # | Common-0 | Common-1 | Common-2 | Req1-3 (F) | Req1-4 (F) |
     # | Req1-5(F)| Req2-0   | Req2-1   | ... |
     req2 = make_request("2", [7] * block_size * 2)
-    computed_blocks = manager.get_computed_blocks(req2)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert not computed_blocks
+    assert num_computed_tokens == 0
     manager.allocate_slots(req2, block_size * 2, computed_blocks)
 
     # Req3 is Req2 + 3 new blocks, so the first 6 blocks are computed,
@@ -556,8 +578,9 @@ def test_prefill_not_enough_free_blocks_with_computed_blocks():
     # In this case, the ref_cnt of the computed blocks should not be changed.
     assert manager.free_block_queue.num_free_blocks == 5
     req3 = make_request("3", common_token_ids * 3)
-    computed_blocks = manager.get_computed_blocks(req3)
+    computed_blocks, num_computed_tokens = manager.get_computed_blocks(req3)
     assert computed_blocks == block_part1
+    assert num_computed_tokens == 6 * 16
     # Req3 cannot be allocated.
     assert manager.allocate_slots(req3, 48, computed_blocks) is None
     # Block 0-2 are used by Req 1.

vllm/v1/core/kv_cache_manager.py

@@ -1,5 +1,5 @@
 from collections import defaultdict
-from typing import Dict, Iterable, List, Optional
+from typing import Dict, Iterable, List, Optional, Tuple
 
 from vllm.logger import init_logger
 from vllm.utils import cdiv
@@ -69,7 +69,8 @@ class KVCacheManager:
         # is finished.
         self.req_to_blocks: Dict[str, List[KVCacheBlock]] = {}
 
-    def get_computed_blocks(self, request: Request) -> List[KVCacheBlock]:
+    def get_computed_blocks(
+            self, request: Request) -> Tuple[List[KVCacheBlock], int]:
         """Get the computed (cached) blocks for the request.
         Note that the computed blocks must be full.
 
@@ -77,11 +78,13 @@ class KVCacheManager:
             request: The request to get the computed blocks.
 
         Returns:
-            A list of blocks that are computed for the request.
+            A tuple containing:
+                - A list of blocks that are computed for the request.
+                - The number of computed tokens.
         """
         if not self.enable_caching:
             # Prefix caching is disabled.
-            return []
+            return [], 0
 
         computed_blocks = []
 
@@ -101,7 +104,11 @@ class KVCacheManager:
             else:
                 break
 
-        return computed_blocks
+        # NOTE(woosuk): Since incomplete blocks are not eligible for
+        # sharing, `num_computed_tokens` is always a multiple of
+        # `block_size`.
+        num_computed_tokens = len(computed_blocks) * self.block_size
+        return computed_blocks, num_computed_tokens
 
     def append_slots(
         self,

vllm/v1/core/scheduler.py

@@ -184,12 +184,8 @@ class Scheduler:
 
                 request = self.waiting[0]
                 # Get already-cached tokens.
-                computed_blocks = self.kv_cache_manager.get_computed_blocks(
+                computed_blocks, num_computed_tokens = \
-                    request)
+                    self.kv_cache_manager.get_computed_blocks(request)
-                # NOTE(woosuk): Since incomplete blocks are not eligible for
-                # sharing, `num_computed_tokens` is always a multiple of
-                # `block_size`.
-                num_computed_tokens = len(computed_blocks) * self.block_size
                 # Number of tokens to be scheduled.
                 # We use `request.num_tokens` instead of
                 # `request.num_prompt_tokens` to consider the resumed requests,