Revert "[v1] Support multiple KV cache groups in GPU model runner (#17945) (#18459)

Signed-off-by: Mark McLoughlin <markmc@redhat.com>

tests/v1/core/test_kv_cache_utils.py

@@ -19,8 +19,7 @@ from vllm.v1.core.kv_cache_utils import (FreeKVCacheBlockQueue, KVCacheBlock,
                                          hash_request_tokens,
                                          unify_kv_cache_configs)
 from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
-                                        KVCacheGroupSpec, KVCacheTensor,
-                                        SlidingWindowSpec)
+                                        KVCacheGroupSpec, KVCacheTensor)
 from vllm.v1.metrics.stats import PrefixCacheStats
 from vllm.v1.request import Request
 
@@ -55,14 +54,12 @@ def new_kv_cache_spec(block_size=16,
                       num_kv_heads=2,
                       head_size=64,
                       dtype=torch.float32,
-                      use_mla=False,
-                      sliding_window=None):
+                      use_mla=False):
     return FullAttentionSpec(block_size=block_size,
                              num_kv_heads=num_kv_heads,
                              head_size=head_size,
                              dtype=dtype,
-                             use_mla=use_mla,
-                             sliding_window=sliding_window)
+                             use_mla=use_mla)
 
 
 def test_none_hash(monkeypatch):
@@ -495,68 +492,6 @@ def test_unify_kv_cache_configs():
         unify_kv_cache_configs(diff_kv_cache_config)
 
 
-def test_merge_kv_cache_spec():
-    same_layer_specs = [
-        new_kv_cache_spec(num_kv_heads=32),
-        new_kv_cache_spec(num_kv_heads=32),
-    ]
-    merged_layer_spec = same_layer_specs[0].merge(same_layer_specs)
-    assert merged_layer_spec.block_size == 16
-    assert merged_layer_spec.num_kv_heads == 32
-    assert merged_layer_spec.head_size == 64
-    assert merged_layer_spec.dtype == torch.float32
-    assert merged_layer_spec.sliding_window is None
-
-    different_layer_specs = [
-        new_kv_cache_spec(num_kv_heads=32),
-        new_kv_cache_spec(num_kv_heads=16),
-    ]
-    with pytest.raises(AssertionError):
-        different_layer_specs[0].merge(different_layer_specs)
-
-    full_spec = new_kv_cache_spec(num_kv_heads=32)
-    different_type_layer_specs = [
-        full_spec,
-        SlidingWindowSpec(
-            block_size=full_spec.block_size,
-            num_kv_heads=full_spec.num_kv_heads,
-            head_size=full_spec.head_size,
-            dtype=full_spec.dtype,
-            use_mla=full_spec.use_mla,
-            sliding_window=1,
-        ),
-    ]
-    with pytest.raises(AssertionError):
-        different_type_layer_specs[0].merge(different_type_layer_specs)
-    with pytest.raises(AssertionError):
-        different_type_layer_specs[1].merge(different_type_layer_specs)
-
-    different_sliding_window_layer_specs = [
-        new_kv_cache_spec(num_kv_heads=32),
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=1),
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=2),
-    ]
-    with pytest.raises(ValueError):
-        different_sliding_window_layer_specs[0].merge(
-            different_sliding_window_layer_specs)
-
-    same_sliding_window_layer_specs = [
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=1),
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=1),
-    ]
-    merged_layer_spec = same_sliding_window_layer_specs[0].merge(
-        same_sliding_window_layer_specs)
-    assert merged_layer_spec.sliding_window == 1
-
-    same_sliding_window_layer_spec_with_none = [
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=1),
-        new_kv_cache_spec(num_kv_heads=32, sliding_window=None),
-    ]
-    merged_layer_spec = same_sliding_window_layer_spec_with_none[0].merge(
-        same_sliding_window_layer_spec_with_none)
-    assert merged_layer_spec.sliding_window == 1
-
-
 @pytest.mark.parametrize(
     ("model_id", "max_model_len", "want_estimated_max_len"), [
         ("Qwen/Qwen1.5-7B", 16385, 16384),

tests/v1/core/test_prefix_caching.py

@@ -84,7 +84,7 @@ def test_prefill(hash_algo):
     blocks = manager.allocate_slots(req0, 55,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
 
     # Check full block metadata
     parent_block_hash = None
@@ -107,13 +107,13 @@ def test_prefill(hash_algo):
     req1 = make_request("1", common_token_ids + unique_token_ids)
     computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert len(manager.req_to_block_hashes[req1.request_id]) == 3
-    assert computed_blocks.get_block_ids() == [[1, 2, 3]]
+    assert computed_blocks.get_block_ids() == [1, 2, 3]
     assert num_computed_tokens == 3 * 16
     num_new_tokens = 53 - 3 * 16
     blocks = manager.allocate_slots(req1, num_new_tokens,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[5]]
+    assert blocks.get_block_ids() == [5]
     for block in computed_blocks.blocks:
         assert block.ref_cnt == 2
 
@@ -141,13 +141,13 @@ def test_prefill(hash_algo):
     req2 = make_request("2", common_token_ids + unique_token_ids)
     computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
     assert len(manager.req_to_block_hashes[req2.request_id]) == 3
-    assert computed_blocks.get_block_ids() == [[1, 2, 3]]
+    assert computed_blocks.get_block_ids() == [1, 2, 3]
     assert num_computed_tokens == 3 * 16
     num_new_tokens = 53 - 3 * 16
     blocks = manager.allocate_slots(req2, num_new_tokens,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[6]]
+    assert blocks.get_block_ids() == [6]
 
     # Although we only have 6 free blocks, we have 8 blocks in
     # the free block queue due to lazy removal.
@@ -171,7 +171,7 @@ def test_prefill(hash_algo):
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
     # This block ID order also checks the eviction order.
-    assert blocks.get_block_ids() == [[7, 8, 9, 10, 4, 5, 6, 3, 2, 1]]
+    assert blocks.get_block_ids() == [7, 8, 9, 10, 4, 5, 6, 3, 2, 1]
     assert manager.block_pool.free_block_queue.num_free_blocks == 0
     assert manager.block_pool.free_block_queue.free_list_head is None
     assert manager.block_pool.free_block_queue.free_list_tail is None
@@ -208,7 +208,7 @@ def test_prefill_plp():
     blocks = manager.allocate_slots(req0, 55,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
     req0_block_hashes = [b.block_hash for b in blocks.blocks]
 
     # Check full block metadata
@@ -233,13 +233,13 @@ def test_prefill_plp():
     req1 = make_request("1", common_token_ids + unique_token_ids)
     computed_blocks, num_computed_tokens = manager.get_computed_blocks(req1)
     assert len(manager.req_to_block_hashes[req1.request_id]) == 3
-    assert computed_blocks.get_block_ids() == [[1, 2, 3]]
+    assert computed_blocks.get_block_ids() == [1, 2, 3]
     assert num_computed_tokens == 3 * 16
     num_new_tokens = 53 - 3 * 16
     blocks = manager.allocate_slots(req1, num_new_tokens,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[5]]
+    assert blocks.get_block_ids() == [5]
     for block in computed_blocks.blocks:
         assert block.ref_cnt == 2
 
@@ -277,11 +277,11 @@ def test_prefill_plp():
     block_ids = blocks.get_block_ids()
     # Duplicate cached blocks have different ids but same hashes vs request #0
     assert [b.block_hash for b in blocks.blocks] == req0_block_hashes
-    assert block_ids != [[1, 2, 3, 4]]
+    assert block_ids != [1, 2, 3, 4]
 
     # Request #2 block hashes are valid since request #0 hashes are.
     # Check block reference counts.
-    for block_id in block_ids[0]:
+    for block_id in block_ids:
         assert manager.block_pool.blocks[block_id].ref_cnt == 1
 
     manager.free(req2)
@@ -307,7 +307,7 @@ def test_decode():
     blocks = manager.allocate_slots(req0, 55,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
 
     # Append slots without allocating a new block.
     req0.num_computed_tokens = 55
@@ -379,12 +379,12 @@ def test_evict():
     # Touch the first 2 blocks.
     req2 = make_request("2", list(range(2 * 16 + 3)))
     computed_blocks, num_computed_tokens = manager.get_computed_blocks(req2)
-    assert computed_blocks.get_block_ids() == [[1, 2]]
+    assert computed_blocks.get_block_ids() == [1, 2]
     assert num_computed_tokens == 2 * 16
     blocks = manager.allocate_slots(req2, 3,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[10]]
+    assert blocks.get_block_ids() == [10]
     assert manager.block_pool.free_block_queue.num_free_blocks == 7
 
 
@@ -625,7 +625,7 @@ def test_mm_prefix_caching():
     blocks = manager.allocate_slots(req0, 59,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
     req0.num_computed_tokens = 59
 
     # Append slots without allocating a new block.
@@ -686,7 +686,7 @@ def test_cache_key_salting():
     blocks = manager.allocate_slots(req0, 59,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
     req0.num_computed_tokens = 59
 
     # Append slots without allocating a new block.
@@ -797,7 +797,7 @@ def test_reset_prefix_cache():
     all_token_ids = full_block_token_ids + unique_token_ids
     req0 = make_request("0", all_token_ids)
     blocks = manager.allocate_slots(req0, 55)
-    assert blocks.get_block_ids() == [[1, 2, 3, 4]]
+    assert blocks.get_block_ids() == [1, 2, 3, 4]
 
     unique_token_ids = [4] * 7
     all_token_ids = full_block_token_ids + unique_token_ids
@@ -808,7 +808,7 @@ def test_reset_prefix_cache():
     blocks = manager.allocate_slots(req1, 7,
                                     len(computed_blocks.blocks) * 16,
                                     computed_blocks)
-    assert blocks.get_block_ids() == [[5]]
+    assert blocks.get_block_ids() == [5]
 
     # Failed to reset prefix cache because some blocks are not freed yet.
     assert not manager.reset_prefix_cache()

tests/v1/worker/test_gpu_input_batch.py

@@ -9,11 +9,9 @@ import torch
 
 from vllm.sampling_params import SamplingParams
 from vllm.utils import is_pin_memory_available, make_tensor_with_pad
-from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
-                                        KVCacheGroupSpec, KVCacheTensor)
 from vllm.v1.sample.metadata import SamplingMetadata
-from vllm.v1.worker.block_table import BlockTable, MultiGroupBlockTable
-from vllm.v1.worker.gpu_input_batch import CachedRequestState, InputBatch
+from vllm.v1.worker.gpu_input_batch import (BlockTable, CachedRequestState,
+                                            InputBatch)
 
 VOCAB_SIZE = 1024
 NUM_OUTPUT_TOKENS = 20
@@ -24,27 +22,6 @@ CUDA_DEVICES = [
 MAX_NUM_PROMPT_TOKENS = 64
 
 
-def get_kv_cache_config() -> KVCacheConfig:
-    return KVCacheConfig(
-        num_blocks=10,
-        tensors={
-            "layer.0": KVCacheTensor(size=1024),
-        },
-        kv_cache_groups=[
-            KVCacheGroupSpec(
-                layer_names=["layer.0"],
-                kv_cache_spec=FullAttentionSpec(
-                    block_size=1,
-                    num_kv_heads=1,
-                    head_size=16,
-                    dtype=torch.float16,
-                    use_mla=False,
-                ),
-            ),
-        ],
-    )
-
-
 def _compare_objs(obj1, obj2):
     attrs = inspect.getmembers(obj1, lambda a: not (inspect.isroutine(a)))
     attr_names = set([
@@ -64,10 +41,6 @@ def _compare_objs(obj1, obj2):
         elif isinstance(a, np.ndarray):
             if np.allclose(a, b):
                 is_same = True
-        elif isinstance(a, MultiGroupBlockTable):
-            for a_i, b_i in zip(a.block_tables, b.block_tables):
-                _compare_objs(a_i, b_i)
-            is_same = True
         elif isinstance(a, (BlockTable, SamplingMetadata)):
             _compare_objs(a, b)
             is_same = True  # if we make it here must be same
@@ -225,7 +198,7 @@ def _construct_cached_request_state(req_id_suffix: int):
         sampling_params=_create_sampling_params(),
         mm_inputs=[],
         mm_positions=[],
-        block_ids=[[]],
+        block_ids=[],
         generator=None,
         num_computed_tokens=len(output_token_ids),
         output_token_ids=output_token_ids,
@@ -247,11 +220,11 @@ def test_sampling_metadata_in_input_batch(device: str, batch_size: int):
     input_batch: InputBatch = InputBatch(
         max_num_reqs=batch_size,
         max_model_len=1024,
+        max_num_blocks_per_req=10,
         max_num_batched_tokens=1024,
         device=torch.device(device),
         pin_memory=is_pin_memory_available(),
         vocab_size=1024,
-        kv_cache_config=get_kv_cache_config(),
     )
     reqs: list[CachedRequestState] = []
     req_id_reqs = {}
@@ -337,20 +310,20 @@ def test_swap_states_in_input_batch(device: str, batch_size: int,
     input_batch: InputBatch = InputBatch(
         max_num_reqs=batch_size,
         max_model_len=1024,
+        max_num_blocks_per_req=10,
         max_num_batched_tokens=1024,
         device=torch.device(device),
         pin_memory=is_pin_memory_available(),
         vocab_size=1024,
-        kv_cache_config=get_kv_cache_config(),
     )
     ref_input_batch: InputBatch = InputBatch(
         max_num_reqs=batch_size,
         max_model_len=1024,
+        max_num_blocks_per_req=10,
         max_num_batched_tokens=1024,
         device=torch.device(device),
         pin_memory=is_pin_memory_available(),
         vocab_size=1024,
-        kv_cache_config=get_kv_cache_config(),
     )
 
     reqs: list[CachedRequestState] = []

tests/v1/worker/test_gpu_model_runner.py

 # SPDX-License-Identifier: Apache-2.0
+import weakref
 
 import pytest
+import torch
 
-from vllm.config import (CacheConfig, ModelConfig, ParallelConfig,
-                         SchedulerConfig, VllmConfig)
+from vllm.config import CacheConfig, ModelConfig, SchedulerConfig, VllmConfig
 from vllm.sampling_params import SamplingParams
 from vllm.v1.core.sched.output import (CachedRequestData, NewRequestData,
                                        SchedulerOutput)
-from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
-                                        KVCacheGroupSpec, KVCacheTensor)
+from vllm.v1.kv_cache_interface import FullAttentionSpec
 from vllm.v1.sample.metadata import SamplingMetadata
-from vllm.v1.worker.gpu_input_batch import InputBatch
 from vllm.v1.worker.gpu_model_runner import GPUModelRunner
 
 
@@ -18,34 +17,13 @@ def initialize_kv_cache(runner: GPUModelRunner):
     """
     Only perform necessary steps in GPUModelRunner.initialize_kv_cache()
     """
-    kv_cache_config = KVCacheConfig(
-        num_blocks=10,
-        tensors={
-            "layer.0": KVCacheTensor(size=1024),
-        },
-        kv_cache_groups=[
-            KVCacheGroupSpec(
-                layer_names=["layer.0"],
-                kv_cache_spec=FullAttentionSpec(
-                    block_size=16,
-                    num_kv_heads=runner.model_config.get_num_kv_heads(
-                        runner.parallel_config),
-                    head_size=runner.model_config.get_head_size(),
-                    dtype=runner.kv_cache_dtype,
-                    use_mla=False,
-                ))
-        ])
-    runner.kv_cache_config = kv_cache_config
-    runner.input_batch = InputBatch(
-        max_num_reqs=runner.max_num_reqs,
-        max_model_len=runner.max_model_len,
-        max_num_batched_tokens=runner.max_num_tokens,
-        device=runner.device,
-        pin_memory=runner.pin_memory,
-        vocab_size=runner.model_config.get_vocab_size(),
-        kv_cache_config=kv_cache_config,
-    )
-    runner.initialize_attn_backend(kv_cache_config)
+    kv_cache_spec = FullAttentionSpec(block_size=16,
+                                      num_kv_heads=1,
+                                      head_size=64,
+                                      dtype=torch.float16,
+                                      use_mla=False)
+    runner.attn_metadata_builder = runner.attn_backend.get_builder_cls()(
+        weakref.proxy(runner), kv_cache_spec, runner.input_batch.block_table)
 
 
 @pytest.fixture
@@ -70,12 +48,10 @@ def model_runner():
         swap_space=0,
         cache_dtype="auto",
     )
-    parallel_config = ParallelConfig()
     vllm_config = VllmConfig(
         model_config=model_config,
         cache_config=cache_config,
         scheduler_config=scheduler_config,
-        parallel_config=parallel_config,
     )
 
     device = "cuda"
@@ -97,7 +73,7 @@ def _schedule_new_request(*req_ids: str) -> SchedulerOutput:
                 mm_hashes=[],
                 mm_positions=[],
                 sampling_params=SamplingParams(),
-                block_ids=[[0]],
+                block_ids=[0],
                 num_computed_tokens=0,
                 lora_request=None,
             ))
@@ -135,14 +111,13 @@ def _is_sampling_metadata_changed(model_runner,
 
 def _is_req_state_block_table_match(model_runner, req_id: str) -> bool:
     req_index = model_runner.input_batch.req_id_to_index[req_id]
-    block_table = model_runner.input_batch.block_table[0]
+    block_table = model_runner.input_batch.block_table
     req_state = model_runner.requests[req_id]
-    if block_table.num_blocks_per_row[req_index] != len(
-            req_state.block_ids[0]):
+    if block_table.num_blocks_per_row[req_index] != len(req_state.block_ids):
         return False
     num_blocks = block_table.num_blocks_per_row[req_index]
     return (block_table.block_table_np[req_index, :num_blocks] ==
-            req_state.block_ids[0]).all()
+            req_state.block_ids).all()
 
 
 def test_update_states_new_request(model_runner):
@@ -225,7 +200,7 @@ def test_update_states_request_resumed(model_runner):
         req_id=req_id,
         resumed_from_preemption=False,
         new_token_ids=[],
-        new_block_ids=[[]],
+        new_block_ids=[],
         num_computed_tokens=0,
     )
 

vllm/distributed/kv_transfer/kv_connector/v1/shared_storage_connector.py

@@ -288,7 +288,7 @@ class SharedStorageConnector(KVConnectorBase_V1):
         for new_req in scheduler_output.scheduled_new_reqs:
             if new_req.req_id in self._requests_need_load:
                 meta.add_request(token_ids=new_req.prompt_token_ids,
-                                 block_ids=new_req.block_ids[0],
+                                 block_ids=new_req.block_ids,
                                  block_size=self._block_size,
                                  is_store=False)
                 total_need_load += 1
@@ -299,7 +299,7 @@ class SharedStorageConnector(KVConnectorBase_V1):
                 # the original prompt tokens.
                 if not self._found_match_for_request(new_req):
                     meta.add_request(token_ids=new_req.prompt_token_ids,
-                                     block_ids=new_req.block_ids[0],
+                                     block_ids=new_req.block_ids,
                                      block_size=self._block_size,
                                      is_store=True)
 
@@ -319,7 +319,7 @@ class SharedStorageConnector(KVConnectorBase_V1):
 
                 # NOTE(rob): For resumed req, new_block_ids is all
                 # of the block_ids for the request.
-                block_ids = cached_req.new_block_ids[0]
+                block_ids = cached_req.new_block_ids
 
                 meta.add_request(token_ids=token_ids,
                                  block_ids=block_ids,

vllm/v1/attention/backends/mla/rocm_aiter_mla.py

@@ -67,13 +67,13 @@ class AiterMLAMetadataBuilder(MLACommonMetadataBuilder[AiterMLAMetadata]):
         max_model_len = self.runner.model_config.max_model_len
         assert max_model_len == 32768,\
             "AITER MLA requires max_model_len=32768"
-        assert self.kv_cache_spec.block_size == 1, "AITER MLA" \
+        assert self.runner.block_size == 1, "AITER MLA" \
             "only supports block size 1."
 
     def _get_paged_kv_tensors(
             self, block_table: torch.Tensor,
             seq_lens: torch.Tensor) -> tuple[torch.Tensor, ...]:
-        page_size = self.kv_cache_spec.block_size
+        page_size = self.runner.block_size
         block_table_bounds = (seq_lens + page_size - 1) // page_size
 
         mask = (torch.arange(block_table.size(1),

vllm/v1/core/kv_cache_manager.py

@@ -32,16 +32,9 @@ class KVCacheBlocks:
         """Creates a new KVCacheBlocks instance with no blocks."""
         return cls([])
 
-    def get_block_ids(self) -> list[list[int]]:
-        """
-        Converts the KVCacheBlocks instance to block_ids.
-        
-        Returns:
-            list[list[int]]: A two-level list where
-            * the outer list corresponds to KV cache groups (only 1 group now)
-            * each inner list contains the block_ids of the blocks in that group
-        """
-        return [[block.block_id for block in self.blocks]]
+    def get_block_ids(self) -> list[int]:
+        """Converts the KVCacheBlocks instance to a list of block IDs."""
+        return [block.block_id for block in self.blocks]
 
     def get_unhashed_block_ids(self) -> list[int]:
         """Get block_ids of unhashed blocks from KVCacheBlocks instance."""
@@ -307,9 +300,9 @@ class KVCacheManager:
         self,
         request: Request,
         num_running_requests: int,
-    ) -> list[int]:
+    ) -> int:
         """Calculate the number of common prefix blocks shared by all requests
-        in the RUNNING state for each kv cache group.
+        in the RUNNING state.
 
         The function determines this by selecting any request and iterating
         through its blocks.  A block is considered a common prefix block if its
@@ -339,14 +332,11 @@ class KVCacheManager:
                 requests in the current step.
 
         Returns:
-            list[int]: The number of common prefix blocks for each kv cache 
-            group.
+            int: The number of common prefix blocks.
         """
         assert request.status == RequestStatus.RUNNING
-        return [
-            self.single_type_manager.get_num_common_prefix_blocks(
-                request.request_id, num_running_requests)
-        ]
+        return self.single_type_manager.get_num_common_prefix_blocks(
+            request.request_id, num_running_requests)
 
     def free_block_hashes(self, request: Request) -> None:
         """Discard the block hashes for the request.
@@ -364,8 +354,10 @@ class KVCacheManager:
         """
         return self.block_pool.take_events()
 
-    def get_block_ids(self, request_id: str) -> list[list[int]]:
+    def get_block_ids(self, request_id: str) -> list[int]:
         """Get the block ids of a request."""
         assert request_id in self.single_type_manager.req_to_blocks
-        return KVCacheBlocks(self.single_type_manager.req_to_blocks[request_id]
-                             ).get_block_ids()
+        return [
+            block.block_id
+            for block in self.single_type_manager.req_to_blocks[request_id]
+        ]

vllm/v1/core/kv_cache_utils.py

@@ -577,12 +577,14 @@ def create_kv_cache_group_specs(
      """
     kv_cache_groups = []
     for layer_names_one_group in grouped_layer_names:
-        layer_specs = [
-            kv_cache_spec[layer_name] for layer_name in layer_names_one_group
-        ]
-        merged_layer_spec = layer_specs[0].merge(layer_specs)
+        layer_spec = kv_cache_spec[layer_names_one_group[0]]
+        assert all(
+            kv_cache_spec[layer_name] == layer_spec
+            for layer_name in layer_names_one_group[1:]), (
+                "All layers in the same KV cache group must share the same "
+                "KVCacheSpec.")
         kv_cache_groups.append(
-            KVCacheGroupSpec(layer_names_one_group, merged_layer_spec))
+            KVCacheGroupSpec(layer_names_one_group, layer_spec))
     return kv_cache_groups
 
 
@@ -681,7 +683,6 @@ def unify_hybrid_kv_cache_specs(kv_cache_spec: dict[str, KVCacheSpec]):
                     head_size=spec.head_size,
                     dtype=spec.dtype,
                     use_mla=spec.use_mla,
-                    sliding_window=spec.sliding_window,
                 )
 
 

vllm/v1/core/sched/output.py

@@ -26,7 +26,7 @@ class NewRequestData:
     mm_hashes: list[str]
     mm_positions: list[PlaceholderRange]
     sampling_params: SamplingParams
-    block_ids: list[list[int]]
+    block_ids: list[int]
     num_computed_tokens: int
     lora_request: Optional[LoRARequest]
 
@@ -34,7 +34,7 @@ class NewRequestData:
     def from_request(
         cls,
         request: Request,
-        block_ids: list[list[int]],
+        block_ids: list[int],
     ) -> NewRequestData:
         return cls(
             req_id=request.request_id,
@@ -85,7 +85,7 @@ class CachedRequestData:
     # request's block IDs instead of appending to the existing block IDs.
     resumed_from_preemption: bool
     new_token_ids: list[int]
-    new_block_ids: list[list[int]]
+    new_block_ids: list[int]
     num_computed_tokens: int
 
     @classmethod
@@ -94,7 +94,7 @@ class CachedRequestData:
         request: Request,
         resumed_from_preemption: bool,
         new_token_ids: list[int],
-        new_block_ids: list[list[int]],
+        new_block_ids: list[int],
     ) -> CachedRequestData:
         return cls(
             req_id=request.request_id,
@@ -131,9 +131,9 @@ class SchedulerOutput:
     # E.g., if a request has [0, 1], it could mean the vision encoder needs
     # to process that the request's 0-th and 1-th images in the current step.
     scheduled_encoder_inputs: dict[str, list[int]]
-    # Number of common prefix blocks for all requests in each KV cache group.
+    # Number of common prefix blocks for all requests.
     # This can be used for cascade attention.
-    num_common_prefix_blocks: list[int]
+    num_common_prefix_blocks: int
 
     # Request IDs that are finished in between the previous and the current
     # steps. This is used to notify the workers about the finished requests

vllm/v1/core/sched/scheduler.py

@@ -173,7 +173,7 @@ class Scheduler(SchedulerInterface):
         # uses structured decoding.
         structured_output_request_ids: dict[str, int] = {}
 
-        req_to_new_block_ids: dict[str, list[list[int]]] = {}
+        req_to_new_block_ids: dict[str, list[int]] = {}
         num_scheduled_tokens: dict[str, int] = {}
         token_budget = self.max_num_scheduled_tokens
         # Encoder-related.
@@ -484,8 +484,7 @@ class Scheduler(SchedulerInterface):
 
         # Get the longest common prefix among all requests in the running queue.
         # This can be potentially used for cascade attention.
-        num_common_prefix_blocks = [0] * len(
-            self.kv_cache_config.kv_cache_groups)
+        num_common_prefix_blocks = 0
         if self.running:
             any_request = self.running[0]
             num_common_prefix_blocks = (
@@ -572,7 +571,7 @@ class Scheduler(SchedulerInterface):
         request: Request,
         num_scheduled_tokens: int,
         num_scheduled_spec_tokens: int,
-        new_block_ids: list[list[int]],
+        new_block_ids: list[int],
         resumed_from_preemption: bool,
     ) -> CachedRequestData:
         # OPTIMIZATION: Cache the CachedRequestData objects to avoid creating
@@ -947,9 +946,7 @@ class Scheduler(SchedulerInterface):
         """
         if self.connector is None:
             return False, None
-        assert len(self.kv_cache_config.kv_cache_groups
-                   ) == 1, "KV connector only supports one KV cache group now"
-        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)[0]
+        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)
         return self.connector.request_finished(request, block_ids)
 
     def _update_waiting_for_remote_kv(self, request: Request) -> bool:
@@ -966,10 +963,9 @@ class Scheduler(SchedulerInterface):
         """
         if request.request_id not in self.finished_recving_kv_req_ids:
             return False
-        assert len(self.kv_cache_config.kv_cache_groups
-                   ) == 1, "KV connector only supports one KV cache group now"
+
         # Now that the blocks are ready, actually cache them.
-        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)[0]
+        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)
         num_computed_tokens = len(block_ids) * self.block_size
         if num_computed_tokens == request.num_tokens:
             num_computed_tokens -= 1

vllm/v1/kv_cache_interface.py

 # SPDX-License-Identifier: Apache-2.0
 
-import copy
 from dataclasses import dataclass
-from typing import Optional
 
 import torch
-from typing_extensions import Self
 
 from vllm.config import VllmConfig
 from vllm.logger import init_logger
@@ -56,16 +53,6 @@ class KVCacheSpec:
         """
         raise NotImplementedError
 
-    @classmethod
-    def merge(cls, specs: list[Self]) -> Self:
-        """
-        Merge a list of KVCacheSpec objects into a single KVCacheSpec object.
-        """
-        assert all(spec.type_id == specs[0].type_id for spec in specs[1:]), (
-            "All layers in the same KV cache group must share the same "
-            "type_id.")
-        return copy.deepcopy(specs[0])
-
 
 @dataclass
 class AttentionSpec(KVCacheSpec):
@@ -84,16 +71,6 @@ class AttentionSpec(KVCacheSpec):
 
 @dataclass
 class FullAttentionSpec(AttentionSpec):
-    sliding_window: Optional[int] = None
-    """
-    When hybrid allocator is disabled and the model contains both full 
-    attention layers and sliding window attention layers, sliding 
-    window attention are regarded as full attention in KV cache manager 
-    (blocks are allocated for all tokens), while computed as sliding window 
-    attention in model runner.
-    In this case, we use FullAttentionSpec and record the sliding window size.
-    Default to None for not using sliding window attention.
-    """
 
     @property
     def type_id(self) -> str:
@@ -103,25 +80,6 @@ class FullAttentionSpec(AttentionSpec):
         max_model_len = vllm_config.model_config.max_model_len
         return cdiv(max_model_len, self.block_size) * self.page_size_bytes
 
-    @classmethod
-    def merge(cls, specs: list[Self]) -> Self:
-        """
-        Merge a list of FullAttentionSpec objects into a single 
-        FullAttentionSpec object.
-        """
-        merged_spec = super().merge(specs)
-        sliding_window = set(spec.sliding_window for spec in specs
-                             if spec.sliding_window is not None)
-        if len(sliding_window) == 0:
-            merged_spec.sliding_window = None
-        elif len(sliding_window) == 1:
-            merged_spec.sliding_window = sliding_window.pop()
-        else:
-            raise ValueError(
-                "All sliding window layers in the same KV cache group "
-                "must have the same window size.")
-        return merged_spec
-
 
 @dataclass
 class SlidingWindowSpec(AttentionSpec):

vllm/v1/worker/block_table.py

@@ -4,8 +4,6 @@ import numpy as np
 import torch
 
 from vllm.logger import init_logger
-from vllm.utils import cdiv
-from vllm.v1.kv_cache_interface import KVCacheConfig
 
 logger = init_logger(__name__)
 
@@ -98,48 +96,3 @@ class BlockTable:
     def get_numpy_array(self) -> np.ndarray:
         """Returns the numpy array of the block table."""
         return self.block_table_np
-
-
-class MultiGroupBlockTable:
-    """The BlockTables for each KV cache group."""
-
-    def __init__(self, max_num_reqs: int, max_model_len: int,
-                 max_num_batched_tokens: int, pin_memory: bool,
-                 device: torch.device, kv_cache_config: KVCacheConfig) -> None:
-        max_num_blocks_per_req = [
-            cdiv(max_model_len, g.kv_cache_spec.block_size)
-            for g in kv_cache_config.kv_cache_groups
-        ]
-        self.block_tables = [
-            BlockTable(max_num_reqs, max_num_blocks_per_req[i],
-                       max_num_batched_tokens, pin_memory, device)
-            for i in range(len(kv_cache_config.kv_cache_groups))
-        ]
-
-    def append_row(self, block_ids: list[list[int]], row_idx: int) -> None:
-        for i, block_table in enumerate(self.block_tables):
-            block_table.append_row(block_ids[i], row_idx)
-
-    def add_row(self, block_ids: list[list[int]], row_idx: int) -> None:
-        for i, block_table in enumerate(self.block_tables):
-            block_table.add_row(block_ids[i], row_idx)
-
-    def move_row(self, src: int, tgt: int) -> None:
-        for block_table in self.block_tables:
-            block_table.move_row(src, tgt)
-
-    def swap_row(self, src: int, tgt: int) -> None:
-        for block_table in self.block_tables:
-            block_table.swap_row(src, tgt)
-
-    def commit(self, num_reqs: int) -> None:
-        for block_table in self.block_tables:
-            block_table.commit(num_reqs)
-
-    def clear(self) -> None:
-        for block_table in self.block_tables:
-            block_table.clear()
-
-    def __getitem__(self, idx: int) -> "BlockTable":
-        """Returns the BlockTable for the i-th KV cache group."""
-        return self.block_tables[idx]

vllm/v1/worker/gpu_input_batch.py

@@ -11,11 +11,10 @@ from vllm.lora.request import LoRARequest
 from vllm.multimodal.inputs import MultiModalKwargs, PlaceholderRange
 from vllm.sampling_params import SamplingParams, SamplingType
 from vllm.utils import swap_dict_values
-from vllm.v1.kv_cache_interface import KVCacheConfig
 from vllm.v1.outputs import LogprobsTensors
 from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.utils import copy_slice
-from vllm.v1.worker.block_table import MultiGroupBlockTable
+from vllm.v1.worker.block_table import BlockTable
 
 _SAMPLING_EPS = 1e-5
 
@@ -30,7 +29,7 @@ class CachedRequestState:
     sampling_params: SamplingParams
     generator: Optional[torch.Generator]
 
-    block_ids: list[list[int]]
+    block_ids: list[int]
     num_computed_tokens: int
     output_token_ids: list[int]
 
@@ -59,14 +58,15 @@ class InputBatch:
         self,
         max_num_reqs: int,
         max_model_len: int,
+        max_num_blocks_per_req: int,
         max_num_batched_tokens: int,
         device: torch.device,
         pin_memory: bool,
         vocab_size: int,
-        kv_cache_config: KVCacheConfig,
     ):
         self.max_num_reqs = max_num_reqs
         self.max_model_len = max_model_len
+        self.max_num_blocks_per_req = max_num_blocks_per_req
         self.max_num_batched_tokens = max_num_batched_tokens
         self.device = device
         self.pin_memory = pin_memory
@@ -99,13 +99,12 @@ class InputBatch:
             self.num_computed_tokens_cpu_tensor.numpy()
 
         # Block table.
-        self.block_table = MultiGroupBlockTable(
+        self.block_table = BlockTable(
             max_num_reqs=max_num_reqs,
-            max_model_len=max_model_len,
+            max_num_blocks_per_req=max_num_blocks_per_req,
             max_num_batched_tokens=max_num_batched_tokens,
             pin_memory=pin_memory,
             device=device,
-            kv_cache_config=kv_cache_config,
         )
 
         # Sampling-related.

vllm/v1/worker/gpu_model_runner.py

@@ -12,8 +12,6 @@ import torch.distributed
 import torch.nn as nn
 
 from vllm.attention import AttentionType, get_attn_backend
-from vllm.attention.backends.abstract import (AttentionBackend,
-                                              AttentionMetadataBuilder)
 from vllm.attention.layer import Attention
 from vllm.attention.utils.fa_utils import get_flash_attn_version
 from vllm.config import (CompilationLevel, VllmConfig,
@@ -34,8 +32,8 @@ from vllm.multimodal.utils import group_mm_inputs_by_modality
 from vllm.sampling_params import SamplingType
 from vllm.sequence import IntermediateTensors
 from vllm.utils import (STR_DTYPE_TO_TORCH_DTYPE, DeviceMemoryProfiler,
-                        GiB_bytes, LazyLoader, cdiv, check_use_alibi,
-                        is_pin_memory_available)
+                        GiB_bytes, LayerBlockType, LazyLoader, cdiv,
+                        check_use_alibi, is_pin_memory_available)
 from vllm.v1.attention.backends.flash_attn import FlashAttentionMetadata
 from vllm.v1.attention.backends.utils import CommonAttentionMetadata
 from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
@@ -53,7 +51,6 @@ from vllm.v1.spec_decode.metadata import SpecDecodeMetadata
 from vllm.v1.spec_decode.ngram_proposer import NgramProposer
 from vllm.v1.spec_decode.utils import is_spec_decode_supported
 from vllm.v1.utils import bind_kv_cache
-from vllm.v1.worker.block_table import BlockTable
 from vllm.v1.worker.gpu_input_batch import CachedRequestState, InputBatch
 from vllm.v1.worker.lora_model_runner_mixin import LoRAModelRunnerMixin
 
@@ -105,17 +102,59 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             self.kv_cache_dtype = STR_DTYPE_TO_TORCH_DTYPE[
                 cache_config.cache_dtype]
 
+        # NOTE(woosuk): sliding_window is None for models with interleaved
+        # attention. Use interleaved_sliding_window instead.
+        self.sliding_window = model_config.get_sliding_window()
+        self.interleaved_sliding_window = getattr(
+            model_config.hf_text_config, "interleaved_sliding_window", None)
+        self.window_size = (self.sliding_window
+                            or self.interleaved_sliding_window)
+
         self.is_multimodal_model = model_config.is_multimodal_model
+        self.block_size = cache_config.block_size
         self.max_model_len = model_config.max_model_len
+        self.max_num_blocks_per_req = cdiv(self.max_model_len, self.block_size)
         self.max_num_tokens = scheduler_config.max_num_batched_tokens
         self.max_num_reqs = scheduler_config.max_num_seqs
 
         # Model-related.
+        self.num_attn_layers = model_config.get_num_layers_by_block_type(
+            parallel_config, LayerBlockType.attention)
         self.num_query_heads = model_config.get_num_attention_heads(
             parallel_config)
+        self.num_kv_heads = model_config.get_num_kv_heads(parallel_config)
+        self.head_size = model_config.get_head_size()
         self.hidden_size = model_config.get_hidden_size()
         self.attention_chunk_size = model_config.attention_chunk_size
 
+        self.attn_backend = get_attn_backend(
+            self.head_size,
+            self.dtype,
+            self.kv_cache_dtype,
+            self.block_size,
+            self.model_config.is_attention_free,
+            use_mla=self.model_config.use_mla,
+        )
+        if self.attn_backend is None:
+            error_msg = (
+                f"Error with get_att_backend: {self.head_size=}, "
+                f"{self.dtype=}, {self.kv_cache_dtype=}, {self.block_size=}, "
+                f"{self.model_config.is_attention_free=}, "
+                f"{self.model_config.use_mla=}")
+            logger.error(error_msg)
+            raise NotImplementedError(
+                "Non-Attention backend is not supported by V1 GPUModelRunner.")
+
+        if self.vllm_config.compilation_config.full_cuda_graph:
+            attn_backend_name = self.attn_backend.__name__
+            flash_attn_version = get_flash_attn_version()
+            if attn_backend_name != "FlashAttentionBackend" or \
+                flash_attn_version != 3:
+                raise ValueError(
+                    f"full_cuda_graph is only supported with "
+                    f"FA3. Current attention backend is {attn_backend_name}, "
+                    f"FlashAttention version is {flash_attn_version}.")
+
         self.cascade_attn_enabled = not self.model_config.disable_cascade_attn
 
         # Multi-modal data support
@@ -137,10 +176,8 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         # self.model: nn.Module  # Set after load_model
         # Initialize in initialize_kv_cache
         self.kv_caches: list[torch.Tensor] = []
-        self.attn_metadata_builders: list[AttentionMetadataBuilder] = []
-        self.attn_backends: list[type[AttentionBackend]] = []
         # self.kv_cache_config: KVCacheConfig
-        # self.input_batch: InputBatch # Persistent batch.
+        # self.attn_metadata_builder: type[AttentionMetadataBuilder]
 
         # req_id -> (input_id -> encoder_output)
         self.encoder_cache: dict[str, dict[int, torch.Tensor]] = {}
@@ -169,6 +206,16 @@ class GPUModelRunner(LoRAModelRunnerMixin):
 
         # Request states.
         self.requests: dict[str, CachedRequestState] = {}
+        # Persistent batch.
+        self.input_batch = InputBatch(
+            max_num_reqs=self.max_num_reqs,
+            max_model_len=self.max_model_len,
+            max_num_blocks_per_req=self.max_num_blocks_per_req,
+            max_num_batched_tokens=self.max_num_tokens,
+            device=self.device,
+            pin_memory=self.pin_memory,
+            vocab_size=model_config.get_vocab_size(),
+        )
 
         self.use_cuda_graph = (self.vllm_config.compilation_config.level
                                == CompilationLevel.PIECEWISE
@@ -263,31 +310,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                                         pin_memory=self.pin_memory)
         self.seq_lens_np = self.seq_lens_cpu.numpy()
 
-    def _may_reorder_batch(self, scheduler_output: "SchedulerOutput") -> bool:
-        """
-        Update the order of requests in the batch based on the attention
-        backend's needs. For example, some attention backends (namely MLA) may 
-        want to separate requests based on if the attention computation will be
-        compute-bound or memory-bound.
-
-        Args:
-            scheduler_output: The scheduler output.
-
-        Returns:
-            True if the batch was reordered, False otherwise.
-        """
-        batch_reordered = self.attn_metadata_builders[0].reorder_batch(
-            self.input_batch, scheduler_output)
-
-        # For models with multiple KV cache groups, the groups should agree on
-        # the same order of requests. We ensure this by only allowing the first
-        # group to reorder the batch and asserting that all other groups do not
-        # reorder the batch.
-        for i in range(1, len(self.kv_cache_config.kv_cache_groups)):
-            assert not self.attn_metadata_builders[i].reorder_batch(
-                self.input_batch, scheduler_output)
-        return batch_reordered
-
     def _update_states(self, scheduler_output: "SchedulerOutput") -> None:
         """Update the cached states and the persistent batch with the scheduler
         output.
@@ -424,8 +446,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             # Update the block IDs.
             if not req_data.resumed_from_preemption:
                 # Append the new blocks to the existing block IDs.
-                for i in range(len(self.kv_cache_config.kv_cache_groups)):
-                    req_state.block_ids[i].extend(req_data.new_block_ids[i])
+                req_state.block_ids.extend(req_data.new_block_ids)
             else:
                 # The request is resumed from preemption.
                 # Replace the existing block IDs with the new ones.
@@ -483,7 +504,11 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         if removed_req_indices:
             self.input_batch.condense(removed_req_indices)
 
-        batch_reordered = self._may_reorder_batch(scheduler_output)
+        # Some attention backends (namely MLA) may want to separate requests
+        # based on if the attention computation will be compute-bound or
+        # memory-bound. This gives them a hook to do that.
+        batch_reordered = self.attn_metadata_builder.reorder_batch(
+            self.input_batch, scheduler_output)
 
         if batch_changed or batch_reordered:
             self.input_batch.refresh_sampling_metadata()
@@ -551,29 +576,21 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                            torch.from_numpy(token_indices),
                            out=self.input_ids_cpu[:total_num_scheduled_tokens])
 
-        # Calculate the slot mapping for each KV cache group.
-        for kv_cache_group_id, kv_cache_group_spec in enumerate(
-                self.kv_cache_config.kv_cache_groups):
-            block_size = kv_cache_group_spec.kv_cache_spec.block_size
-            block_table: BlockTable = self.input_batch.block_table[
-                kv_cache_group_id]
-            # E.g., [0, 1, 0, 1, 2, 3, 4, 0, 1, 2]
-            # -> [0, 0, K, K, K + 1, K + 1, K + 2, 2 * K, 2 * K, 2 * K + 1]
-            # where K is the max_num_blocks_per_req and the block size is 2.
-            # NOTE(woosuk): We can't simply use `token_indices // block_size`
-            # here because M (max_model_len) is not necessarily divisible by
-            # block_size.
-            block_table_indices = (
-                req_indices * block_table.max_num_blocks_per_req +
-                positions_np // block_size)
-            block_table_cpu = block_table.get_cpu_tensor()
-            block_numbers = block_table_cpu.flatten(
-            )[block_table_indices].numpy()
-            block_offsets = positions_np % block_size
-            np.add(
-                block_numbers * block_size,
-                block_offsets,
-                out=block_table.slot_mapping_np[:total_num_scheduled_tokens])
+        # Calculate the slot mapping.
+        # E.g., [0, 1, 0, 1, 2, 3, 4, 0, 1, 2]
+        # -> [0, 0, K, K, K + 1, K + 1, K + 2, 2 * K, 2 * K, 2 * K + 1]
+        # where K is the max_num_blocks_per_req and the block size is 2.
+        # NOTE(woosuk): We can't simply use `token_indices // block_size` here
+        # because M (max_model_len) is not necessarily divisible by block_size.
+        block_table_indices = (req_indices * self.max_num_blocks_per_req +
+                               positions_np // self.block_size)
+        block_table_cpu = self.input_batch.block_table.get_cpu_tensor()
+        block_numbers = block_table_cpu.flatten()[block_table_indices].numpy()
+        block_offsets = positions_np % self.block_size
+        np.add(block_numbers * self.block_size,
+               block_offsets,
+               out=self.input_batch.block_table.
+               slot_mapping_np[:total_num_scheduled_tokens])
 
         # Prepare the attention metadata.
         self.query_start_loc_np[0] = 0
@@ -615,6 +632,10 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         attn_metadata: dict[str, FlashAttentionMetadata] = {}
         # Prepare the attention metadata for each KV cache group and make layers
         # in the same group share the same metadata.
+        # NOTE(Chen): there is exactly one KV cache group that contains all
+        # attetnion layers in the model for now, so the current logic for
+        # getting attn_metadata is not related to kv_cache_group information.
+        # Will extend this part to support multiple KV cache groups later.
         for kv_cache_group_id, kv_cache_group_spec in enumerate(
                 self.kv_cache_config.kv_cache_groups):
 
@@ -623,19 +644,15 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             if self.cascade_attn_enabled:
                 common_prefix_len = self._compute_cascade_attn_prefix_len(
                     num_scheduled_tokens,
-                    scheduler_output.
-                    num_common_prefix_blocks[kv_cache_group_id],
-                    kv_cache_group_spec.kv_cache_spec,
-                    self.attn_metadata_builders[kv_cache_group_id],
+                    scheduler_output.num_common_prefix_blocks,
                 )
 
-            attn_metadata_i = (
-                self.attn_metadata_builders[kv_cache_group_id].build(
-                    num_reqs=num_reqs,
-                    num_actual_tokens=total_num_scheduled_tokens,
-                    max_query_len=max_num_scheduled_tokens,
-                    common_prefix_len=common_prefix_len,
-                    common_attn_metadata=common_attn_metadata))
+            attn_metadata_i = self.attn_metadata_builder.build(
+                num_reqs=num_reqs,
+                num_actual_tokens=total_num_scheduled_tokens,
+                max_query_len=max_num_scheduled_tokens,
+                common_prefix_len=common_prefix_len,
+                common_attn_metadata=common_attn_metadata)
             for layer_name in kv_cache_group_spec.layer_names:
                 attn_metadata[layer_name] = attn_metadata_i
 
@@ -673,8 +690,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         self,
         num_scheduled_tokens: np.ndarray,
         num_common_prefix_blocks: int,
-        kv_cache_spec: KVCacheSpec,
-        attn_metadata_builder: AttentionMetadataBuilder,
     ) -> int:
         """Compute the length of the common prefix for cascade attention.
 
@@ -693,7 +708,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         Returns:
             int: Length of common prefix in tokens.
         """
-        common_prefix_len = num_common_prefix_blocks * kv_cache_spec.block_size
+        common_prefix_len = num_common_prefix_blocks * self.block_size
         if common_prefix_len == 0:
             # Common case.
             return 0
@@ -742,19 +757,15 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             common_prefix_len,
             self.input_batch.num_computed_tokens_cpu[:num_reqs].min())
         # common_prefix_len should be a multiple of the block size.
-        common_prefix_len = (common_prefix_len // kv_cache_spec.block_size *
-                             kv_cache_spec.block_size)
-        use_sliding_window = (isinstance(kv_cache_spec, SlidingWindowSpec) or
-                              (isinstance(kv_cache_spec, FullAttentionSpec)
-                               and kv_cache_spec.sliding_window is not None))
-        assert isinstance(kv_cache_spec, AttentionSpec)
-        use_cascade = attn_metadata_builder.use_cascade_attention(
+        common_prefix_len = (common_prefix_len // self.block_size *
+                             self.block_size)
+        use_cascade = self.attn_metadata_builder.use_cascade_attention(
             common_prefix_len=common_prefix_len,
             query_lens=num_scheduled_tokens,
             num_query_heads=self.num_query_heads,
-            num_kv_heads=kv_cache_spec.num_kv_heads,
+            num_kv_heads=self.num_kv_heads,
             use_alibi=self.use_alibi,
-            use_sliding_window=use_sliding_window,
+            use_sliding_window=self.window_size is not None,
             num_sms=self.num_sms,
         )
         return common_prefix_len if use_cascade else 0
@@ -1640,7 +1651,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                                         dtype=np.int32)
 
         if skip_attn:
-            attn_metadata: Optional[dict[str, FlashAttentionMetadata]] = None
+            attn_metadata = None
         else:
             query_start_loc = self.query_start_loc[:num_reqs + 1]
             seq_lens = self.seq_lens[:num_reqs]
@@ -1648,19 +1659,13 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             common_attn_metadata = CommonAttentionMetadata(
                 query_start_loc=query_start_loc, seq_lens=seq_lens)
 
-            attn_metadata = {}
-            for kv_cache_group_id, kv_cache_group_spec in enumerate(
-                    self.kv_cache_config.kv_cache_groups):
-                attn_metadata_i = (
-                    self.attn_metadata_builders[kv_cache_group_id].build(
-                        num_reqs=num_tokens,
-                        num_actual_tokens=num_tokens,
-                        max_query_len=num_tokens,
-                        common_prefix_len=0,
-                        common_attn_metadata=common_attn_metadata,
-                    ))
-                for layer_name in kv_cache_group_spec.layer_names:
-                    attn_metadata[layer_name] = attn_metadata_i
+            attn_metadata = self.attn_metadata_builder.build(
+                num_reqs=num_tokens,
+                num_actual_tokens=num_tokens,
+                max_query_len=num_tokens,
+                common_prefix_len=0,
+                common_attn_metadata=common_attn_metadata,
+            )
 
         with self.maybe_dummy_run_with_lora(self.lora_config,
                                             num_scheduled_tokens):
@@ -1890,56 +1895,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         logger.info("Graph capturing finished in %.0f secs, took %.2f GiB",
                     elapsed_time, cuda_graph_size / (1 << 30))
 
-    def initialize_attn_backend(self, kv_cache_config: KVCacheConfig) -> None:
-        """
-        Initialize the attention backends and attention metadata builders.
-        """
-        assert len(self.attn_backends) == 0 and len(
-            self.attn_metadata_builders
-        ) == 0, "Attention backends are already initialized"
-        for i, kv_cache_group_spec in enumerate(
-                kv_cache_config.kv_cache_groups):
-            kv_cache_spec = kv_cache_group_spec.kv_cache_spec
-            if not isinstance(kv_cache_spec, AttentionSpec):
-                raise NotImplementedError(
-                    "Only AttentionSpec is supported for now.")
-            attn_backend_i = get_attn_backend(
-                kv_cache_spec.head_size,
-                self.dtype,
-                kv_cache_spec.dtype,
-                kv_cache_spec.block_size,
-                self.model_config.is_attention_free,
-                use_mla=kv_cache_spec.use_mla,
-            )
-            if attn_backend_i is None:
-                error_msg = (
-                    f"Error with get_attn_backend: {kv_cache_spec.head_size=}, "
-                    f"{self.dtype=}, {kv_cache_spec.dtype=}, "
-                    f"{kv_cache_spec.block_size=}, "
-                    f"{self.model_config.is_attention_free=}, "
-                    f"{kv_cache_spec.use_mla=}")
-                logger.error(error_msg)
-                raise NotImplementedError(
-                    "Non-Attention backend is not supported by V1 "
-                    "GPUModelRunner.")
-
-            if self.vllm_config.compilation_config.full_cuda_graph:
-                attn_backend_name = attn_backend_i.__name__
-                flash_attn_version = get_flash_attn_version()
-                if attn_backend_name != "FlashAttentionBackend" or \
-                    flash_attn_version != 3:
-                    raise ValueError(
-                        f"full_cuda_graph is only supported with "
-                        f"FA3. Current attention backend is "
-                        f"{attn_backend_name}, FlashAttention version is "
-                        f"{flash_attn_version}.")
-
-            block_table_i = self.input_batch.block_table[i]
-            attn_metadata_builder_i = attn_backend_i.get_builder_cls()(
-                weakref.proxy(self), kv_cache_spec, block_table_i)
-            self.attn_backends.append(attn_backend_i)
-            self.attn_metadata_builders.append(attn_metadata_builder_i)
-
     def initialize_kv_cache(self, kv_cache_config: KVCacheConfig) -> None:
         """
         Initialize KV cache based on `kv_cache_config`.
@@ -1947,21 +1902,15 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             kv_cache_config: Configuration for the KV cache, including the KV
             cache size of each layer
         """
+        if len(kv_cache_config.kv_cache_groups) > 1:
+            raise NotImplementedError(
+                "Hybrid models with more than one KV cache type are not "
+                "supported yet.")
         self.kv_cache_config = kv_cache_config
-        self.input_batch = InputBatch(
-            max_num_reqs=self.max_num_reqs,
-            max_model_len=self.max_model_len,
-            max_num_batched_tokens=self.max_num_tokens,
-            device=self.device,
-            pin_memory=self.pin_memory,
-            vocab_size=self.model_config.get_vocab_size(),
-            kv_cache_config=kv_cache_config,
-        )
-        self.initialize_attn_backend(kv_cache_config)
 
         kv_caches: dict[str, torch.Tensor] = {}
 
-        for i, kv_cache_group in enumerate(kv_cache_config.kv_cache_groups):
+        for kv_cache_group in kv_cache_config.kv_cache_groups:
             kv_cache_spec = kv_cache_group.kv_cache_spec
             for layer_name in kv_cache_group.layer_names:
                 tensor_config = kv_cache_config.tensors[layer_name]
@@ -1976,7 +1925,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                 # the min of all `num_blocks`. Verify it here.
                 assert num_blocks >= kv_cache_config.num_blocks
                 if isinstance(kv_cache_spec, AttentionSpec):
-                    kv_cache_shape = self.attn_backends[i].get_kv_cache_shape(
+                    kv_cache_shape = self.attn_backend.get_kv_cache_shape(
                         num_blocks, kv_cache_spec.block_size,
                         kv_cache_spec.num_kv_heads, kv_cache_spec.head_size)
                     dtype = kv_cache_spec.dtype
@@ -1996,6 +1945,11 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         if has_kv_transfer_group():
             get_kv_transfer_group().register_kv_caches(kv_caches)
 
+        self.attn_metadata_builder = self.attn_backend.get_builder_cls()(
+            weakref.proxy(self),
+            kv_cache_config.kv_cache_groups[0].kv_cache_spec,
+            self.input_batch.block_table)
+
     def get_kv_cache_spec(self) -> dict[str, KVCacheSpec]:
         """
         Generates the KVCacheSpec by parsing the kv cache format from each

vllm/v1/worker/tpu_model_runner.py

@@ -171,10 +171,19 @@ class TPUModelRunner(LoRAModelRunnerMixin):
         self.kv_caches: list[torch.Tensor] = []
         # req_id -> (input_id -> encoder_output)
         self.encoder_cache: dict[str, dict[int, torch.Tensor]] = {}
-        # self.input_batch: InputBatch  # Persistent batch.
 
         # Request states.
         self.requests: dict[str, CachedRequestState] = {}
+        # Persistent batch.
+        self.input_batch = InputBatch(
+            max_num_reqs=self.max_num_reqs,
+            max_model_len=self.max_model_len,
+            max_num_blocks_per_req=self.max_num_blocks_per_req,
+            max_num_batched_tokens=self.max_num_tokens,
+            device=self.device,
+            pin_memory=self.pin_memory,
+            vocab_size=self.vocab_size,
+        )
 
         # Cached torch/numpy tensor
         # The pytorch tensor and numpy array share the same buffer.
@@ -190,7 +199,7 @@ class TPUModelRunner(LoRAModelRunnerMixin):
 
         self.block_table_cpu = torch.zeros(
             (self.max_num_reqs, self.max_num_blocks_per_req),
-            dtype=torch.int32,
+            dtype=self.input_batch.block_table.get_cpu_tensor().dtype,
             device="cpu")
 
         self.query_start_loc_cpu = torch.zeros(self.max_num_tokens + 1,
@@ -515,12 +524,12 @@ class TPUModelRunner(LoRAModelRunnerMixin):
         # NOTE(woosuk): We use torch.index_select instead of np.take here
         # because torch.index_select is much faster than np.take for large
         # tensors.
-        block_table_cpu = self.input_batch.block_table[0].get_cpu_tensor()
+        block_table_cpu = self.input_batch.block_table.get_cpu_tensor()
         block_numbers = block_table_cpu.flatten()[block_table_indices].numpy()
         block_offsets = positions_np % self.block_size
         np.add(block_numbers * self.block_size,
                block_offsets,
-               out=self.input_batch.block_table[0].
+               out=self.input_batch.block_table.
                slot_mapping_np[:total_num_scheduled_tokens])
 
         # Prepare the attention metadata.
@@ -545,15 +554,15 @@ class TPUModelRunner(LoRAModelRunnerMixin):
         self.position_ids = self.positions_cpu[:
                                                padded_total_num_scheduled_tokens].to(
                                                    self.device)
-        self.input_batch.block_table[0].slot_mapping_cpu[
+        self.input_batch.block_table.slot_mapping_cpu[
             total_num_scheduled_tokens:] = _PAD_SLOT_ID
         slot_mapping = (
-            self.input_batch.block_table[0].
+            self.input_batch.block_table.
             slot_mapping_cpu[:padded_total_num_scheduled_tokens].to(
                 self.device))
         block_tables = self.block_table_cpu[:self.max_num_reqs]
         block_tables[:num_reqs, :self.max_num_blocks_per_req] = (
-            self.input_batch.block_table[0].get_cpu_tensor()[:num_reqs])
+            self.input_batch.block_table.get_cpu_tensor()[:num_reqs])
         block_tables = block_tables.to(self.device)
         query_start_loc = self.query_start_loc_cpu[:self.max_num_reqs + 1].to(
             self.device)
@@ -1254,18 +1263,6 @@ class TPUModelRunner(LoRAModelRunnerMixin):
                 "Hybrid models with more than one KV cache type are not "
                 "supported yet.")
 
-        self.input_batch = InputBatch(
-            max_num_reqs=self.max_num_reqs,
-            max_model_len=self.max_model_len,
-            max_num_batched_tokens=self.max_num_tokens,
-            device=self.device,
-            pin_memory=self.pin_memory,
-            vocab_size=self.model_config.get_vocab_size(),
-            kv_cache_config=kv_cache_config,
-        )
-        assert self.block_table_cpu.dtype == self.input_batch.block_table[
-            0].get_cpu_tensor().dtype
-
         kv_caches: dict[str, torch.Tensor] = {}
 
         for kv_cache_group in kv_cache_config.kv_cache_groups: