[V1] Optimize handling of sampling metadata and req_ids list (#13244)

Signed-off-by: Nick Hill <nhill@redhat.com>

tests/v1/sample/test_rejection_sampler.py

@@ -26,17 +26,13 @@ def create_logits_tensor(token_ids: List[int],
 def create_sampling_metadata(spec_tokens: List[List[int]]) -> SamplingMetadata:
     batch_size = len(spec_tokens)
     return SamplingMetadata(
-        temperature=0.0,
+        temperature=torch.tensor([]),
         all_greedy=True,
         all_random=False,
-        rejection_sampling=True,
         spec_token_ids=spec_tokens,
         top_p=None,
         top_k=None,
-        no_top_p=False,
-        no_top_k=False,
         min_p=torch.empty(batch_size, ),
-        no_min_p=True,
         generators={},
         max_num_logprobs=0,
         no_penalties=False,
@@ -45,8 +41,7 @@ def create_sampling_metadata(spec_tokens: List[List[int]]) -> SamplingMetadata:
         presence_penalties=torch.tensor([]),
         repetition_penalties=torch.tensor([]),
         output_token_ids=[],
-        min_tokens=[],
-        stop_token_ids=[],
+        min_tokens={},
         logit_bias=[None] * batch_size,
     )
 

tests/v1/sample/test_sampler.py

@@ -77,25 +77,20 @@ def _create_default_sampling_metadata(
         temperature=torch.full((batch_size, ), 0.0),
         all_greedy=True,
         all_random=False,
-        rejection_sampling=False,
-        top_p=torch.empty(batch_size, ),
-        top_k=torch.empty(batch_size, ),
-        no_top_p=True,
-        no_top_k=True,
-        min_p=torch.empty(batch_size, ),
-        no_min_p=True,
+        top_p=None,
+        top_k=None,
+        min_p=None,
         generators={},
         max_num_logprobs=0,
         prompt_token_ids=_create_prompt_tokens_tensor(prompt_token_ids,
                                                       vocab_size, device),
         output_token_ids=output_token_ids,
-        spec_token_ids=[],
+        spec_token_ids=None,
         frequency_penalties=_create_penalty_tensor(batch_size, 0.0, device),
         presence_penalties=_create_penalty_tensor(batch_size, 0.0, device),
         repetition_penalties=_create_penalty_tensor(batch_size, 1.0, device),
         no_penalties=True,
-        min_tokens=[],
-        stop_token_ids=[],
+        min_tokens={},
         logit_bias=[None] * batch_size,
     )
     return fake_sampling_metadata
@@ -104,10 +99,10 @@ def _create_default_sampling_metadata(
 def _generate_min_token_penalties_and_stop_tokens(
     num_output_tokens: int, batch_size: int, vocab_size: int,
     batch_indices_for_min_token_penalty: List[int]
-) -> Tuple[List[int], List[Set[int]]]:
+) -> Dict[int, Tuple[int, Set[int]]]:
     """
-    Generates and returns a list of minimum token penalties (`min_tokens`)
-    and a corresponding list of stop token IDs (`stop_token_ids`) for each
+    Generates and returns a dict of minimum token penalties and
+    corresponding stop token IDs (`min_tokens`, `stop_token_ids`) for each
     batch.
 
     If a batch index is included in `batch_indices_for_min_token_penalty`,
@@ -115,22 +110,19 @@ def _generate_min_token_penalties_and_stop_tokens(
     and a random set of stop token IDs is created. Otherwise, a lower
     `min_tokens` value is assigned, and the stop token IDs set is empty.
     """
-    stop_token_ids: List[Set[int]] = []
-    min_tokens: List[int] = []
+    min_tokens: Dict[int, Tuple[int, Set[int]]] = {}
     for index in range(batch_size):
         if index in batch_indices_for_min_token_penalty:
-            min_tokens.append(
+            min_tokens[index] = (
                 np.random.randint(num_output_tokens + 1,
-                                  2 * num_output_tokens))
-            stop_token_ids.append(
+                                  2 * num_output_tokens),
                 set(
                     np.random.randint(0, vocab_size - 1)
                     for _ in range(np.random.randint(0, vocab_size))))
-
         else:
-            min_tokens.append(np.random.randint(0, num_output_tokens))
-            stop_token_ids.append(set())
-    return (min_tokens, stop_token_ids)
+            min_tokens[index] = (np.random.randint(0,
+                                                   num_output_tokens), set())
+    return min_tokens
 
 
 def _create_weighted_output_token_list(
@@ -165,7 +157,7 @@ def _create_weighted_output_token_list(
             output_token_ids_for_batch.extend(
                 [token_id for _ in range(index + 1)])
         output_token_ids.append(output_token_ids_for_batch)
-    return (output_token_ids, sorted_token_ids_in_output)
+    return output_token_ids, sorted_token_ids_in_output
 
 
 @pytest.mark.parametrize("device", CUDA_DEVICES)
@@ -182,17 +174,17 @@ def test_sampler_min_tokens_penalty(device: str, batch_size: int):
         NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE, torch.device(device))
     batch_indices_for_min_token_penalty = np.random.randint(
         0, batch_size - 1, size=np.random.randint(0, batch_size)).tolist()
-    min_tokens, stop_token_ids = _generate_min_token_penalties_and_stop_tokens(
+    min_tokens = _generate_min_token_penalties_and_stop_tokens(
         NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE,
         batch_indices_for_min_token_penalty)
     sampling_metadata.min_tokens = min_tokens
-    sampling_metadata.stop_token_ids = stop_token_ids
     sampler = Sampler()
     logits = sampler.apply_penalties(fake_logits, sampling_metadata)
     logits = logits.cpu()
     for batch_idx in range(batch_size):
         for token_id in range(VOCAB_SIZE):
-            if token_id in stop_token_ids[batch_idx]:
+            _, stop_token_ids = min_tokens.get(batch_idx, (0, set()))
+            if token_id in stop_token_ids:
                 assert logits[batch_idx][token_id] == -float("inf")
             else:
                 assert logits[batch_idx][token_id] != -float("inf")

tests/v1/worker/test_gpu_input_batch.py

 # SPDX-License-Identifier: Apache-2.0
 
-from typing import Dict, List, Set, Tuple
+from typing import Dict, List, Optional, Set, Tuple
 
 import numpy as np
 import pytest
@@ -41,7 +41,7 @@ def _remove_requests(
     for index in req_indices_to_remove:
         input_batch.remove_request(reqs[index].req_id)
         req_ids_to_remove.add(reqs[index].req_id)
-    return (req_ids_to_remove, req_indices_to_remove_list)
+    return req_ids_to_remove, req_indices_to_remove_list
 
 
 def _construct_expected_sampling_metadata(
@@ -64,8 +64,7 @@ def _construct_expected_sampling_metadata(
     top_p = [0.0 for _ in range(num_reqs)]
     min_p = [0.0 for _ in range(num_reqs)]
     temperature = [0.0 for _ in range(num_reqs)]
-    stop_token_ids: List[Set[int]] = [set() for _ in range(num_reqs)]
-    min_tokens = [0 for _ in range(num_reqs)]
+    min_tokens = {}
     logit_bias = [None] * num_reqs
     for req in reqs:
         if req.req_id not in req_ids_retained:
@@ -83,22 +82,21 @@ def _construct_expected_sampling_metadata(
         top_p[index_in_input_batch] = req.sampling_params.top_p
         min_p[index_in_input_batch] = req.sampling_params.min_p
         temperature[index_in_input_batch] = req.sampling_params.temperature
-        stop_token_ids[
-            index_in_input_batch] = req.sampling_params.all_stop_token_ids
-        min_tokens[index_in_input_batch] = req.sampling_params.min_tokens
+        min_tokens[index_in_input_batch] = (
+            req.sampling_params.min_tokens,
+            req.sampling_params.all_stop_token_ids)
         logit_bias[index_in_input_batch] = req.sampling_params.logit_bias
     return SamplingMetadata(
         temperature=torch.tensor(temperature, dtype=torch.float,
                                  device=device),
         all_greedy=False,
         all_random=True,
-        rejection_sampling=False,
-        top_p=torch.tensor(top_p, dtype=torch.float, device=device),
-        top_k=torch.tensor(top_k, dtype=torch.int, device=device),
-        no_top_p=all(x == 1.0 for x in top_p),
-        no_top_k=all(x == 0 for x in top_k),
-        min_p=torch.tensor(min_p, dtype=torch.float, device=device),
-        no_min_p=all(x == 0.0 for x in min_p),
+        top_p=None if all(x == 1.0 for x in top_p) else torch.tensor(
+            top_p, dtype=torch.float, device=device),
+        top_k=None if all(x == 0 for x in top_k) else torch.tensor(
+            top_k, dtype=torch.int, device=device),
+        min_p=None if all(x == 0.0 for x in min_p) else torch.tensor(
+            min_p, dtype=torch.float, device=device),
         generators={},
         max_num_logprobs=0,
         prompt_token_ids=make_tensor_with_pad(
@@ -117,9 +115,8 @@ def _construct_expected_sampling_metadata(
                                           dtype=torch.float,
                                           device=device),
         output_token_ids=output_token_ids,
-        spec_token_ids=[],
+        spec_token_ids=None,
         min_tokens=min_tokens,
-        stop_token_ids=stop_token_ids,
         no_penalties=(all(x == 0 for x in presence_penalties)
                       and all(x == 0 for x in frequency_penalties)
                       and all(x == 1 for x in repetition_penalties)),
@@ -206,8 +203,7 @@ def test_sampling_metadata_in_input_batch(device: str, batch_size: int):
     input_batch.condense(req_indices_to_remove)
 
     # Generate the sampling metadata
-    sampling_metadata = input_batch.make_sampling_metadata(
-        req_id_output_token_ids, req_id_to_spec_token_ids={}, skip_copy=False)
+    sampling_metadata = input_batch._make_sampling_metadata()
 
     # Create expected output.
     expected_sampling_metadata = _construct_expected_sampling_metadata(
@@ -216,13 +212,16 @@ def test_sampling_metadata_in_input_batch(device: str, batch_size: int):
         input_batch.req_id_to_index,
         device=torch.device(device))
 
+    def same(t1: Optional[torch.Tensor], t2: Optional[torch.Tensor]) -> bool:
+        return (t1 is None
+                and t2 is None) or (t1 is not None and t2 is not None
+                                    and torch.allclose(t1, t2))
+
     # Assert the actual and expected output.
     assert torch.allclose(expected_sampling_metadata.temperature,
                           sampling_metadata.temperature)
-    assert torch.allclose(expected_sampling_metadata.top_p,
-                          sampling_metadata.top_p)
-    assert torch.allclose(expected_sampling_metadata.top_k,
-                          sampling_metadata.top_k)
+    assert same(expected_sampling_metadata.top_p, sampling_metadata.top_p)
+    assert same(expected_sampling_metadata.top_k, sampling_metadata.top_k)
     assert torch.allclose(
         expected_sampling_metadata.frequency_penalties,
         sampling_metadata.frequency_penalties,
@@ -240,10 +239,6 @@ def test_sampling_metadata_in_input_batch(device: str, batch_size: int):
     assert (expected_sampling_metadata.output_token_ids ==
             sampling_metadata.output_token_ids)
     assert expected_sampling_metadata.min_tokens == sampling_metadata.min_tokens
-    assert expected_sampling_metadata.stop_token_ids == \
-           sampling_metadata.stop_token_ids
     assert expected_sampling_metadata.no_penalties == \
            sampling_metadata.no_penalties
-    assert expected_sampling_metadata.no_top_p == sampling_metadata.no_top_p
-    assert expected_sampling_metadata.no_top_k == sampling_metadata.no_top_k
     assert expected_sampling_metadata.logit_bias == sampling_metadata.logit_bias

tests/v1/worker/test_gpu_model_runner.py

@@ -5,6 +5,7 @@ from vllm.config import CacheConfig, ModelConfig, SchedulerConfig, VllmConfig
 from vllm.sampling_params import SamplingParams
 from vllm.v1.core.scheduler_output import (CachedRequestData, NewRequestData,
                                            SchedulerOutput)
+from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.worker.gpu_model_runner import GPUModelRunner
 
 
@@ -82,14 +83,21 @@ def _is_req_added(model_runner, req_id: str) -> bool:
     return req_id in model_runner.requests
 
 
+def _is_sampling_metadata_changed(model_runner,
+                                  sampling_metadata_before: SamplingMetadata):
+    return model_runner.input_batch.sampling_metadata is not (
+        sampling_metadata_before)
+
+
 def test_update_states_new_request(model_runner):
     req_id = "req_0"
 
     # new req
     scheduler_output = _schedule_new_request(req_id)
 
-    batch_changed = model_runner._update_states(scheduler_output)
-    assert batch_changed is True
+    metadata_before = model_runner.input_batch.sampling_metadata
+    model_runner._update_states(scheduler_output)
+    assert _is_sampling_metadata_changed(model_runner, metadata_before)
     assert _is_req_added(model_runner, req_id)
     assert _is_req_scheduled(model_runner, req_id)
 
@@ -117,8 +125,9 @@ def test_update_states_request_finished(model_runner):
         free_encoder_input_ids=[],
     )
 
-    batch_changed = model_runner._update_states(scheduler_output)
-    assert batch_changed is True
+    metadata_before = model_runner.input_batch.sampling_metadata
+    model_runner._update_states(scheduler_output)
+    assert _is_sampling_metadata_changed(model_runner, metadata_before)
     assert not _is_req_added(model_runner, req_id)
     assert not _is_req_scheduled(model_runner, req_id)
 
@@ -142,7 +151,7 @@ def test_update_states_request_resumed(model_runner):
         scheduled_spec_decode_tokens={},
         scheduled_encoder_inputs={},
         num_common_prefix_blocks=0,
-        finished_req_ids={},
+        finished_req_ids=set(),
         free_encoder_input_ids=[],
     )
 
@@ -171,8 +180,9 @@ def test_update_states_request_resumed(model_runner):
         free_encoder_input_ids=[],
     )
 
-    batch_changed = model_runner._update_states(scheduler_output)
-    assert batch_changed is True
+    metadata_before = model_runner.input_batch.sampling_metadata
+    model_runner._update_states(scheduler_output)
+    assert _is_sampling_metadata_changed(model_runner, metadata_before)
     assert _is_req_added(model_runner, req_id)
     assert _is_req_scheduled(model_runner, req_id)
 
@@ -200,8 +210,9 @@ def test_update_states_no_changes(model_runner):
         free_encoder_input_ids=[],
     )
 
-    batch_changed = model_runner._update_states(scheduler_output)
-    assert batch_changed is False
+    metadata_before = model_runner.input_batch.sampling_metadata
+    model_runner._update_states(scheduler_output)
+    assert not _is_sampling_metadata_changed(model_runner, metadata_before)
     assert _is_req_added(model_runner, req_id)
     assert _is_req_scheduled(model_runner, req_id)
 
@@ -233,8 +244,8 @@ def test_update_states_request_unscheduled(model_runner):
         free_encoder_input_ids=[],
     )
 
-    batch_changed = model_runner._update_states(scheduler_output)
-    assert batch_changed is True
+    metadata_before = model_runner._update_states(scheduler_output)
+    assert _is_sampling_metadata_changed(model_runner, metadata_before)
 
     assert _is_req_added(model_runner, req_ids[0])
     assert _is_req_scheduled(model_runner, req_ids[0])

vllm/model_executor/layers/utils.py

@@ -45,7 +45,7 @@ def apply_penalties(logits: torch.Tensor, prompt_tokens_tensor: torch.Tensor,
                                                    vocab_size, num_seqs)
     output_bin_counts, output_mask = get_token_bin_counts_and_mask(
         output_tokens_tensor, vocab_size, num_seqs)
-    repetition_penalties = repetition_penalties.unsqueeze_(dim=1).repeat(
+    repetition_penalties = repetition_penalties.unsqueeze(dim=1).repeat(
         1, vocab_size)
     logits[logits > 0] /= torch.where(prompt_mask | output_mask,
                                       repetition_penalties, 1.0)[logits > 0]
@@ -53,6 +53,6 @@ def apply_penalties(logits: torch.Tensor, prompt_tokens_tensor: torch.Tensor,
                                        repetition_penalties, 1.0)[logits <= 0]
     # We follow the definition in OpenAI API.
     # Refer to https://platform.openai.com/docs/api-reference/parameter-details
-    logits -= frequency_penalties.unsqueeze_(dim=1) * output_bin_counts
-    logits -= presence_penalties.unsqueeze_(dim=1) * output_mask
+    logits -= frequency_penalties.unsqueeze(dim=1) * output_bin_counts
+    logits -= presence_penalties.unsqueeze(dim=1) * output_mask
     return logits

vllm/v1/core/scheduler.py

@@ -195,8 +195,10 @@ class Scheduler:
                                              request.num_computed_tokens -
                                              request.num_tokens)
                 if num_scheduled_spec_tokens > 0:
+                    # Trim spec_token_ids list to num_scheduled_spec_tokens.
+                    del request.spec_token_ids[num_scheduled_spec_tokens:]
                     scheduled_spec_decode_tokens[request.request_id] = (
-                        request.spec_token_ids[:num_scheduled_spec_tokens])
+                        request.spec_token_ids)
 
             # Encoder-related.
             if encoder_inputs_to_schedule:
@@ -567,7 +569,7 @@ class Scheduler:
                 outputs.append(
                     EngineCoreOutput(
                         request_id=req_id,
-                        new_token_ids=new_token_ids or [],
+                        new_token_ids=new_token_ids,
                         finish_reason=request.get_finished_reason(),
                         new_logprobs=new_logprobs,
                         new_prompt_logprobs_tensors=prompt_logprobs_tensors,

vllm/v1/sample/metadata.py

 # SPDX-License-Identifier: Apache-2.0
 
 from dataclasses import dataclass
-from typing import Dict, List, Optional, Set
+from typing import Dict, List, Optional, Set, Tuple
 
 import torch
 
@@ -12,15 +12,13 @@ class SamplingMetadata:
     temperature: torch.Tensor
     all_greedy: bool
     all_random: bool
-    rejection_sampling: bool
-    spec_token_ids: List[List[int]]
 
-    top_p: torch.Tensor
-    top_k: torch.Tensor
-    no_top_p: bool
-    no_top_k: bool
-    min_p: torch.Tensor
-    no_min_p: bool
+    # None when there are no speculated tokens.
+    spec_token_ids: Optional[List[List[int]]]
+
+    top_p: Optional[torch.Tensor]
+    top_k: Optional[torch.Tensor]
+    min_p: Optional[torch.Tensor]
 
     generators: Dict[int, torch.Generator]
 
@@ -34,7 +32,8 @@ class SamplingMetadata:
     repetition_penalties: torch.Tensor
 
     output_token_ids: List[List[int]]
-    min_tokens: List[int]
-    stop_token_ids: List[Set[int]]
+
+    # req_index -> (min_tokens, stop_token_ids)
+    min_tokens: Dict[int, Tuple[int, Set[int]]]
 
     logit_bias: List[Optional[Dict[int, float]]]

vllm/v1/sample/ops/penalties.py

 # SPDX-License-Identifier: Apache-2.0
 
-from typing import List, Set, Tuple
+from typing import Dict, List, Set, Tuple
 
 import torch
 
@@ -8,18 +8,17 @@ from vllm.model_executor.layers.utils import apply_penalties
 from vllm.utils import is_pin_memory_available, make_tensor_with_pad
 
 
-def apply_min_token_penalties(logits: torch.Tensor,
-                              output_token_ids: List[List[int]],
-                              stop_token_ids: List[Set[int]],
-                              min_tokens: List[int]) -> None:
+def apply_min_token_penalties(
+        logits: torch.Tensor, output_token_ids: List[List[int]],
+        min_tokens: Dict[int, Tuple[int, Set[int]]]) -> None:
     """
     Applies minimum token penalty by setting the logits of the stop tokens
     to -inf.
     """
     min_tokens_logits_to_penalize: List[Tuple[int, int]] = []
-    for index, min_token in enumerate(min_tokens):
+    for index, (min_token, stop_token_ids) in min_tokens.items():
         if len(output_token_ids[index]) < min_token:
-            for stop_token_id in stop_token_ids[index]:
+            for stop_token_id in stop_token_ids:
                 min_tokens_logits_to_penalize.append((index, stop_token_id))
     if min_tokens_logits_to_penalize:
         logits[tuple(zip(*min_tokens_logits_to_penalize))] = -float("inf")

vllm/v1/sample/ops/topk_topp_sampler.py

 # SPDX-License-Identifier: Apache-2.0
 
-from typing import Dict
+from typing import Dict, Optional
 
 import torch
 import torch.nn as nn
@@ -55,13 +55,11 @@ class TopKTopPSampler(nn.Module):
         self,
         logits: torch.Tensor,
         generators: Dict[int, torch.Generator],
-        no_top_k: bool,
-        k: torch.Tensor,
-        no_top_p: bool,
-        p: torch.Tensor,
+        k: Optional[torch.Tensor],
+        p: Optional[torch.Tensor],
     ) -> torch.Tensor:
         """PyTorch-native implementation of top-k and top-p sampling."""
-        logits = apply_top_k_top_p(logits, no_top_k, k, no_top_p, p)
+        logits = apply_top_k_top_p(logits, k, p)
         probs = logits.softmax(dim=-1, dtype=torch.float32)
         return random_sample(probs, generators)
 
@@ -69,37 +67,33 @@ class TopKTopPSampler(nn.Module):
         self,
         logits: torch.Tensor,
         generators: Dict[int, torch.Generator],
-        no_top_k: bool,
-        k: torch.Tensor,
-        no_top_p: bool,
-        p: torch.Tensor,
+        k: Optional[torch.Tensor],
+        p: Optional[torch.Tensor],
     ) -> torch.Tensor:
         """More optimized implementation for top-k and top-p sampling."""
         probs = logits.softmax(dim=-1, dtype=torch.float32)
-        if no_top_k and no_top_p:
+        if k is None and p is None:
             # We prefer `random_sample` over `flashinfer_sample` when sorting is
             # not needed. This is because `random_sample` does not require
             # CPU-GPU synchronization while `flashinfer_sample` does.
             return random_sample(probs, generators)
-        return flashinfer_sample(probs, no_top_k, k, no_top_p, p, generators)
+        return flashinfer_sample(probs, k, p, generators)
 
 
 def apply_top_k_top_p(
     logits: torch.Tensor,
-    no_top_k: bool,
-    k: torch.Tensor,
-    no_top_p: bool,
-    p: torch.Tensor,
+    k: Optional[torch.Tensor],
+    p: Optional[torch.Tensor],
 ) -> torch.Tensor:
     """Apply top-k and top-p masks to the logits.
 
     This function sorts the logits tensor, which can be slow for large batches.
     """
-    if no_top_k and no_top_p:
+    if k is None and p is None:
         return logits
     logits_sort, logits_idx = logits.sort(dim=-1, descending=False)
 
-    if not no_top_k:
+    if k is not None:
         # Apply top-k.
         top_k_mask = logits_sort.size(1) - k.to(torch.long)
         # Get all the top_k values.
@@ -107,7 +101,7 @@ def apply_top_k_top_p(
         top_k_mask = logits_sort < top_k_mask
         logits_sort.masked_fill_(top_k_mask, -float("inf"))
 
-    if not no_top_p:
+    if p is not None:
         # Apply top-p.
         probs_sort = logits_sort.softmax(dim=-1)
         probs_sum = probs_sort.cumsum(dim=-1)
@@ -147,10 +141,8 @@ def random_sample(
 
 def flashinfer_sample(
     probs: torch.Tensor,
-    no_top_k: bool,
-    k: torch.Tensor,
-    no_top_p: bool,
-    p: torch.Tensor,
+    k: Optional[torch.Tensor],
+    p: Optional[torch.Tensor],
     generators: Dict[int, torch.Generator],
 ) -> torch.Tensor:
     """Sample from the probabilities using FlashInfer.
@@ -167,7 +159,7 @@ def flashinfer_sample(
     does not. Call this function at the end of the forward pass to minimize
     the synchronization overhead.
     """
-    assert not (no_top_k and no_top_p)
+    assert not (k is None and p is None)
     max_top_k_round = 32
     batch_size = probs.shape[0]
     uniform_samples = torch.empty((max_top_k_round, batch_size),
@@ -178,11 +170,11 @@ def flashinfer_sample(
         for i, generator in generators.items():
             uniform_samples[:, i].uniform_(generator=generator)
 
-    if no_top_k:
+    if k is None:
         # Top-p only.
         next_token_ids, success = flashinfer.sampling.top_p_sampling_from_probs(
             probs, uniform_samples, p, deterministic=True)
-    elif no_top_p:
+    elif p is None:
         # Top-k only.
         next_token_ids, success = flashinfer.sampling.top_k_sampling_from_probs(
             probs, uniform_samples, k, deterministic=True)
@@ -194,9 +186,9 @@ def flashinfer_sample(
 
     # NOTE: CPU-GPU synchronization happens here.
     if not success.all():
-        if not no_top_k:
+        if k is not None:
             probs = flashinfer.sampling.top_k_renorm_prob(probs, k)
-        if not no_top_p:
+        if p is not None:
             probs = flashinfer.sampling.top_p_renorm_prob(probs, p)
         next_token_ids = flashinfer.sampling.sampling_from_probs(
             probs, uniform_samples[0], deterministic=True)

vllm/v1/sample/rejection_sampler.py

@@ -68,6 +68,7 @@ class RejectionSampler(nn.Module):
         # NOTE: The following input preparationg can be moved
         # to the model runner with a persistent manner for better
         # performance.
+        assert sampling_metadata.spec_token_ids is not None
         spec_token_ids = sampling_metadata.spec_token_ids
         max_spec_len = max(len(s) for s in spec_token_ids)
         batch_size = len(spec_token_ids)
@@ -119,6 +120,7 @@ class RejectionSampler(nn.Module):
         logits: torch.Tensor,
         sampling_metadata: SamplingMetadata,
     ) -> SamplerOutput:
+        assert sampling_metadata.spec_token_ids is not None
         spec_lens = [len(x) for x in sampling_metadata.spec_token_ids]
         # Add 1 to include the 'bonus' token.
         sample_lens = [x + 1 for x in spec_lens]

vllm/v1/sample/sampler.py

@@ -26,7 +26,7 @@ class Sampler(nn.Module):
         logits: torch.Tensor,
         sampling_metadata: SamplingMetadata,
     ) -> SamplerOutput:
-        if sampling_metadata.rejection_sampling:
+        if sampling_metadata.spec_token_ids:
             if sampling_metadata.max_num_logprobs:
                 raise NotImplementedError(
                     "Rejection sampling does not support logprobs.")
@@ -104,16 +104,14 @@ class Sampler(nn.Module):
         logits = self.apply_temperature(logits, sampling_metadata.temperature)
 
         # Apply min_p.
-        if not sampling_metadata.no_min_p:
+        if sampling_metadata.min_p is not None:
             logits = self.apply_min_p(logits, sampling_metadata.min_p)
 
         # Apply top_k and/or top_p.
         random_sampled = self.topk_topp_sampler(
             logits,
             sampling_metadata.generators,
-            sampling_metadata.no_top_k,
             sampling_metadata.top_k,
-            sampling_metadata.no_top_p,
             sampling_metadata.top_p,
         )
 
@@ -179,9 +177,10 @@ class Sampler(nn.Module):
         logits: torch.Tensor,
         sampling_metadata: SamplingMetadata,
     ) -> torch.Tensor:
-        apply_min_token_penalties(logits, sampling_metadata.output_token_ids,
-                                  sampling_metadata.stop_token_ids,
-                                  sampling_metadata.min_tokens)
+        if sampling_metadata.min_tokens:
+            apply_min_token_penalties(logits,
+                                      sampling_metadata.output_token_ids,
+                                      sampling_metadata.min_tokens)
         if not sampling_metadata.no_penalties:
             assert sampling_metadata.prompt_token_ids is not None
             logits = apply_all_penalties(

vllm/v1/utils.py

@@ -188,3 +188,14 @@ def bind_kv_cache(
     for layer_name, kv_cache in kv_caches.items():
         # NOTE: Use list because of v0 PP virtual engine.
         forward_context[layer_name].kv_cache = [kv_cache]
+
+
+def copy_slice(from_tensor: torch.Tensor, to_tensor: torch.Tensor,
+               length: int) -> None:
+    """
+    Copy the first length elements of a tensor into another tensor in a
+    non-blocking manner.
+
+    Used to copy pinned CPU tensor data to pre-allocated GPU tensors.
+    """
+    to_tensor[:length].copy_(from_tensor[:length], non_blocking=True)

vllm/v1/worker/gpu_input_batch.py

 # SPDX-License-Identifier: Apache-2.0
-
 # Datastructures defining an input batch
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple, cast
 
 import numpy as np
 import torch
@@ -12,6 +11,7 @@ from vllm.lora.request import LoRARequest
 from vllm.multimodal import MultiModalKwargs
 from vllm.sampling_params import SamplingParams, SamplingType
 from vllm.v1.sample.metadata import SamplingMetadata
+from vllm.v1.utils import copy_slice
 from vllm.v1.worker.block_table import BlockTable
 
 _SAMPLING_EPS = 1e-5
@@ -63,7 +63,7 @@ class InputBatch:
         self.pin_memory = pin_memory
         self.vocab_size = vocab_size
 
-        self.req_ids: List[Optional[str]] = [None] * max_num_reqs
+        self._req_ids: List[Optional[str]] = []
         self.req_id_to_index: Dict[str, int] = {}
 
         # TODO(woosuk): This buffer could be too large if max_model_len is big.
@@ -171,11 +171,8 @@ class InputBatch:
                 self.repetition_penalties_cpu_tensor.numpy()
         self.repetition_penalties_reqs: Set[str] = set()
 
-        self.min_tokens: List[int] = [0] * max_num_reqs
-        self.stop_token_ids: List[Set[int]] = [
-            set() for _ in range(max_num_reqs)
-        ]
-        self.prompt_token_ids: Optional[torch.Tensor] = None
+        # req_index -> (min_tokens, stop_token_ids)
+        self.min_tokens: Dict[int, Tuple[int, Set[int]]] = {}
 
         # lora related
         self.request_lora_mapping = np.zeros((self.max_num_reqs, ),
@@ -196,6 +193,17 @@ class InputBatch:
         self.logit_bias: List[Optional[Dict[int,
                                             float]]] = [None] * max_num_reqs
 
+        self.req_output_token_ids: List[Optional[List[int]]] = []
+
+        # This is updated each time the batch constituents change.
+        self.sampling_metadata = self._make_sampling_metadata()
+
+    @property
+    def req_ids(self) -> List[str]:
+        # None elements should only be present transiently
+        # while performing state updates to the batch.
+        return cast(List[str], self._req_ids)
+
     def add_request(
         self,
         request: "CachedRequestState",
@@ -206,7 +214,13 @@ class InputBatch:
         assert req_index < self.max_num_reqs
 
         req_id = request.req_id
-        self.req_ids[req_index] = req_id
+        if req_index == len(self._req_ids):
+            self._req_ids.append(req_id)
+            self.req_output_token_ids.append(request.output_token_ids)
+        else:
+            self._req_ids[req_index] = req_id
+            self.req_output_token_ids[req_index] = request.output_token_ids
+
         self.req_id_to_index[req_id] = req_index
 
         # Copy the prompt token ids and output token ids.
@@ -255,8 +269,9 @@ class InputBatch:
             req_index] = sampling_params.repetition_penalty
         if sampling_params.repetition_penalty != 1.0:
             self.repetition_penalties_reqs.add(req_id)
-        self.min_tokens[req_index] = sampling_params.min_tokens
-        self.stop_token_ids[req_index] = sampling_params.all_stop_token_ids
+        if sampling_params.min_tokens:
+            self.min_tokens[req_index] = (sampling_params.min_tokens,
+                                          sampling_params.all_stop_token_ids)
 
         # NOTE(woosuk): self.generators should not include the requests that
         # do not have their own generator.
@@ -284,16 +299,20 @@ class InputBatch:
             self.request_lora_mapping[req_index] = 0
 
     def remove_request(self, req_id: str) -> Optional[int]:
+        """This method must always be followed by a call to condense()."""
+
         req_index = self.req_id_to_index.pop(req_id, None)
         if req_index is None:
             return None
-        self.req_ids[req_index] = None
+        self._req_ids[req_index] = None
+        self.req_output_token_ids[req_index] = None
 
         self.greedy_reqs.discard(req_id)
         self.random_reqs.discard(req_id)
         self.top_p_reqs.discard(req_id)
         self.top_k_reqs.discard(req_id)
         self.min_p_reqs.discard(req_id)
+        self.min_tokens.pop(req_index, None)
         self.frequency_penalties_reqs.discard(req_id)
         self.presence_penalties_reqs.discard(req_id)
         self.repetition_penalties_reqs.discard(req_id)
@@ -313,33 +332,17 @@ class InputBatch:
         self.logit_bias[req_index] = None
         return req_index
 
-    def clear(self) -> None:
-        self.req_ids = [None] * self.max_num_reqs
-        self.req_id_to_index.clear()
-        self.greedy_reqs.clear()
-        self.random_reqs.clear()
-        self.top_p_reqs.clear()
-        self.top_k_reqs.clear()
-        self.min_p_reqs.clear()
-        self.frequency_penalties_reqs.clear()
-        self.presence_penalties_reqs.clear()
-        self.repetition_penalties_reqs.clear()
-        self.generators.clear()
-        self.num_logprobs.clear()
-        self.num_prompt_logprobs.clear()
-        self.request_lora_mapping.fill(0)
-        self.lora_id_to_lora_request.clear()
-        self.lora_id_to_request_ids.clear()
-        self.logit_bias = [None] * self.max_num_reqs
-
     def condense(self, empty_req_indices: List[int]) -> None:
-        if self.num_reqs == 0:
+        num_reqs = self.num_reqs
+        if num_reqs == 0:
             # The batched states are empty.
+            self._req_ids.clear()
+            self.req_output_token_ids.clear()
             return
 
         # NOTE(woosuk): This function assumes that the empty_req_indices
         # is sorted in descending order.
-        last_req_index = self.num_reqs + len(empty_req_indices) - 1
+        last_req_index = num_reqs + len(empty_req_indices) - 1
         while empty_req_indices:
             # Find the largest non-empty index.
             while last_req_index in empty_req_indices:
@@ -351,10 +354,13 @@ class InputBatch:
                 break
 
             # Swap the states.
-            req_id = self.req_ids[last_req_index]
+            req_id = self._req_ids[last_req_index]
+            output_token_ids = self.req_output_token_ids[last_req_index]
             assert req_id is not None
-            self.req_ids[empty_index] = req_id
-            self.req_ids[last_req_index] = None
+            self._req_ids[empty_index] = req_id
+            self._req_ids[last_req_index] = None
+            self.req_output_token_ids[empty_index] = output_token_ids
+            self.req_output_token_ids[last_req_index] = None
             self.req_id_to_index[req_id] = empty_index
 
             num_tokens = self.num_tokens[last_req_index]
@@ -379,13 +385,14 @@ class InputBatch:
             self.repetition_penalties_cpu[
                 empty_index] = self.repetition_penalties_cpu[last_req_index]
             self.min_p_cpu[empty_index] = self.min_p_cpu[last_req_index]
-            self.min_tokens[empty_index] = self.min_tokens[last_req_index]
-            self.stop_token_ids[empty_index] = self.stop_token_ids[
-                last_req_index]
             generator = self.generators.pop(last_req_index, None)
             if generator is not None:
                 self.generators[empty_index] = generator
 
+            min_token = self.min_tokens.pop(last_req_index, None)
+            if min_token is not None:
+                self.min_tokens[empty_index] = min_token
+
             self.request_lora_mapping[empty_index] = self.request_lora_mapping[
                 last_req_index]
 
@@ -394,87 +401,71 @@ class InputBatch:
             # Decrement last_req_index since it is now empty.
             last_req_index -= 1
 
-    def make_sampling_metadata(
-        self,
-        req_id_output_token_ids: Dict[str, List[int]],
-        req_id_to_spec_token_ids: Dict[str, List[int]],
-        skip_copy: bool = False,
-    ) -> SamplingMetadata:
-        if not skip_copy:
-            self.temperature[:self.num_reqs].copy_(
-                self.temperature_cpu_tensor[:self.num_reqs], non_blocking=True)
-            self.top_p[:self.num_reqs].copy_(
-                self.top_p_cpu_tensor[:self.num_reqs], non_blocking=True)
-            self.top_k[:self.num_reqs].copy_(
-                self.top_k_cpu_tensor[:self.num_reqs], non_blocking=True)
-            self.min_p[:self.num_reqs].copy_(
-                self.min_p_cpu_tensor[:self.num_reqs], non_blocking=True)
-            if not self.no_penalties:
-                # Since syncing these tensors is expensive only copy them
-                # if necessary i.e. if there are requests which require
-                # penalties to be applied during sampling.
-                self.frequency_penalties[:self.num_reqs].copy_(
-                    self.frequency_penalties_cpu_tensor[:self.num_reqs],
-                    non_blocking=True,
-                )
-                self.presence_penalties[:self.num_reqs].copy_(
-                    self.presence_penalties_cpu_tensor[:self.num_reqs],
-                    non_blocking=True,
-                )
-                self.repetition_penalties[:self.num_reqs].copy_(
-                    self.repetition_penalties_cpu_tensor[:self.num_reqs],
-                    non_blocking=True,
-                )
-                # The prompt tokens are used only for applying penalties during
-                # the sampling process. Hence copy these tensors only when
-                # there are requests which need penalties to be applied.
-                self.prompt_token_ids = self._make_prompt_token_ids_tensor()
-
-        output_token_ids: List[List[int]] = []
-        spec_token_ids: List[List[int]] = []
-        rejection_sampling = False
-        for req_id in self.req_ids[:self.num_reqs]:
-            assert req_id is not None
-            # Currently we create a tensor for output_token_ids from scratch
-            # at each step. However, for the penalties computation what we
-            # need is stats about the token ids present in the output. This
-            # stats can be maintained incrementally instead of computing it
-            # from scratch at each step.
-            # TODO - Replace this with incremental update to output token
-            # statistics.
-            output_token_ids.append(req_id_output_token_ids[req_id])
-            req_spec_token_ids = req_id_to_spec_token_ids.get(req_id, [])
-            spec_token_ids.append(req_spec_token_ids)
-            if req_spec_token_ids:
-                # If any of the requests require speculative decoding, set the
-                # flag to True.
-                rejection_sampling = True
+        # Trim lists to the batch size.
+        del self._req_ids[self.num_reqs:]
+        del self.req_output_token_ids[self.num_reqs:]
+
+    def refresh_sampling_metadata(self):
+        self.sampling_metadata = self._make_sampling_metadata()
+
+    def _make_sampling_metadata(self) -> SamplingMetadata:
+        num_reqs = self.num_reqs
+        copy_slice(self.temperature_cpu_tensor, self.temperature, num_reqs)
+        if not self.no_top_p:
+            copy_slice(self.top_p_cpu_tensor, self.top_p, num_reqs)
+        if not self.no_top_k:
+            copy_slice(self.top_k_cpu_tensor, self.top_k, num_reqs)
+        if not self.no_min_p:
+            copy_slice(self.min_p_cpu_tensor, self.min_p, num_reqs)
+
+        if not self.no_penalties:
+            # Since syncing these tensors is expensive only copy them
+            # if necessary i.e. if there are requests which require
+            # penalties to be applied during sampling.
+            copy_slice(self.frequency_penalties_cpu_tensor,
+                       self.frequency_penalties, num_reqs)
+            copy_slice(self.presence_penalties_cpu_tensor,
+                       self.presence_penalties, num_reqs)
+            copy_slice(self.repetition_penalties_cpu_tensor,
+                       self.repetition_penalties, num_reqs)
+
+            # The prompt tokens are used only for applying penalties during
+            # the sampling process. Hence copy these tensors only when
+            # there are requests which need penalties to be applied.
+            prompt_token_ids = self._make_prompt_token_ids_tensor()
+        else:
+            prompt_token_ids = None
 
         return SamplingMetadata(
-            temperature=self.temperature[:self.num_reqs],
+            temperature=self.temperature[:num_reqs],
             all_greedy=self.all_greedy,
             all_random=self.all_random,
-            rejection_sampling=rejection_sampling,
-            top_p=self.top_p[:self.num_reqs],
-            top_k=self.top_k[:self.num_reqs],
-            min_p=self.min_p[:self.num_reqs],
-            no_min_p=self.no_min_p,
-            no_top_p=self.no_top_p,
-            no_top_k=self.no_top_k,
+            top_p=None if self.no_top_p else self.top_p[:num_reqs],
+            top_k=None if self.no_top_k else self.top_k[:num_reqs],
+            min_p=None if self.no_min_p else self.min_p[:num_reqs],
             generators=self.generators,
             max_num_logprobs=self.max_num_logprobs,
-            prompt_token_ids=self.prompt_token_ids,
-            frequency_penalties=self.frequency_penalties[:self.num_reqs],
-            presence_penalties=self.presence_penalties[:self.num_reqs],
-            repetition_penalties=self.repetition_penalties[:self.num_reqs],
-            output_token_ids=output_token_ids,
-            spec_token_ids=spec_token_ids,
-            min_tokens=self.min_tokens[:self.num_reqs],
-            stop_token_ids=self.stop_token_ids[:self.num_reqs],
+            prompt_token_ids=prompt_token_ids,
+            frequency_penalties=self.frequency_penalties[:num_reqs],
+            presence_penalties=self.presence_penalties[:num_reqs],
+            repetition_penalties=self.repetition_penalties[:num_reqs],
+            output_token_ids=cast(List[List[int]], self.req_output_token_ids),
+            spec_token_ids=None,
+            min_tokens=self.min_tokens,
             no_penalties=self.no_penalties,
-            logit_bias=self.logit_bias[:self.num_reqs],
+            logit_bias=self.logit_bias[:num_reqs],
         )
 
+    def get_sampling_metadata(
+        self,
+        req_id_to_spec_token_ids: Dict[str, List[int]],
+    ) -> SamplingMetadata:
+        # Set the new spec token ids in the cached sampling metadata.
+        self.sampling_metadata.spec_token_ids = [
+            req_id_to_spec_token_ids.get(req_id, []) for req_id in self.req_ids
+        ] if req_id_to_spec_token_ids else None
+        return self.sampling_metadata
+
     def _make_prompt_token_ids_tensor(self) -> torch.Tensor:
         max_prompt_len = self.num_prompt_tokens[:self.num_reqs].max()
         prompt_token_ids_cpu_tensor = torch.empty(

vllm/v1/worker/gpu_model_runner.py

@@ -31,7 +31,6 @@ from vllm.v1.engine.mm_input_cache import MMInputCacheClient
 from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
                                         KVCacheSpec)
 from vllm.v1.outputs import LogprobsTensors, ModelRunnerOutput
-from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.sample.rejection_sampler import INVALID_TOKEN_ID
 from vllm.v1.spec_decode.ngram_proposer import NgramProposer
 from vllm.v1.utils import bind_kv_cache
@@ -224,16 +223,15 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                                         pin_memory=self.pin_memory)
         self.seq_lens_np = self.seq_lens_cpu.numpy()
 
-    def _update_states(self, scheduler_output: "SchedulerOutput") -> bool:
+    def _update_states(self, scheduler_output: "SchedulerOutput") -> None:
         """Update the cached states and the persistent batch with the scheduler
         output.
 
         The updated states are used by the `_prepare_inputs` function to create
         the input GPU tensors for the model.
 
-        Returns:
-            True if there is a new/resumed/paused/finished request in the batch.
-            If False, we can skip copying SamplingMetadata to the GPU.
+        The SamplingMetadata is updated and copied to the GPU if there is a
+        new/resumed/paused/finished request in the batch.
         """
         # Remove finished requests from the cached states.
         for req_id in scheduler_output.finished_req_ids:
@@ -344,9 +342,12 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             num_new_tokens = (num_computed_tokens +
                               len(req_data.new_token_ids) -
                               req_state.num_tokens)
-            new_token_ids = (req_data.new_token_ids[-num_new_tokens:]
-                             if num_new_tokens > 0 else [])
-            req_state.output_token_ids.extend(new_token_ids)
+            if num_new_tokens == 1:
+                # Avoid slicing list in most common case.
+                req_state.output_token_ids.append(req_data.new_token_ids[-1])
+            elif num_new_tokens > 0:
+                req_state.output_token_ids.extend(
+                    req_data.new_token_ids[-num_new_tokens:])
             # Update the block IDs.
             if not req_data.resumed_from_preemption:
                 # Append the new blocks to the existing block IDs.
@@ -380,7 +381,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             self.input_batch.num_tokens_no_spec[req_index] = end_token_index
             # Add spec_token_ids to token_ids_cpu.
             spec_token_ids = scheduler_output.scheduled_spec_decode_tokens.get(
-                req_id, [])
+                req_id, ())
             if spec_token_ids:
                 start_index = end_token_index
                 end_token_index += len(spec_token_ids)
@@ -410,7 +411,8 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         if removed_req_indices:
             self.input_batch.condense(removed_req_indices)
 
-        return batch_changed
+        if batch_changed:
+            self.input_batch.refresh_sampling_metadata()
 
     def _prepare_inputs(
         self,
@@ -429,8 +431,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         # TODO: The Python loop can be slow. Optimize.
         num_scheduled_tokens = np.empty(num_reqs, dtype=np.int32)
         max_num_scheduled_tokens = 0
-        for i, req_id in zip(range(num_reqs), self.input_batch.req_ids):
-            assert req_id is not None
+        for i, req_id in enumerate(self.input_batch.req_ids):
             num_tokens = scheduler_output.num_scheduled_tokens[req_id]
             num_scheduled_tokens[i] = num_tokens
             max_num_scheduled_tokens = max(max_num_scheduled_tokens,
@@ -669,10 +670,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
 
     def _calc_mrope_positions(self, scheduler_output: "SchedulerOutput"):
         mrope_pos_ptr = 0
-        num_reqs = self.input_batch.num_reqs
-        for index, req_id in enumerate(self.input_batch.req_ids[:num_reqs]):
-            assert req_id is not None
-
+        for index, req_id in enumerate(self.input_batch.req_ids):
             req = self.requests[req_id]
             assert req.mrope_positions is not None
 
@@ -726,12 +724,11 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         self,
         scheduler_output: "SchedulerOutput",
         cu_num_tokens: np.ndarray,
-    ) -> Tuple[torch.Tensor, torch.Tensor]:
+    ) -> torch.Tensor:
         # Get the number of spec decode tokens for each request.
         num_reqs = self.input_batch.num_reqs
         num_spec_decode_tokens = np.empty(num_reqs, dtype=np.int32)
-        for i, req_id in zip(range(num_reqs), self.input_batch.req_ids):
-            assert req_id is not None
+        for i, req_id in enumerate(self.input_batch.req_ids):
             num_spec_decode_tokens[i] = len(
                 scheduler_output.scheduled_spec_decode_tokens.get(req_id, ()))
 
@@ -769,22 +766,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         return torch.from_numpy(spec_decode_logits_indices).to(
             self.device, non_blocking=True)
 
-    def _prepare_sampling(
-        self,
-        batch_changed: bool,
-        req_to_spec_token_ids: Dict[str, List[int]],
-    ) -> SamplingMetadata:
-        # Create the sampling metadata.
-        req_id_output_token_ids: Dict[str, List[int]] = \
-            {req_id: req.output_token_ids \
-                for req_id, req in self.requests.items()}
-
-        sampling_metadata = self.input_batch.make_sampling_metadata(
-            req_id_output_token_ids,
-            req_to_spec_token_ids,
-            skip_copy=not batch_changed)
-        return sampling_metadata
-
     def _execute_encoder(self, scheduler_output: "SchedulerOutput"):
         scheduled_encoder_inputs = scheduler_output.scheduled_encoder_inputs
         if not scheduled_encoder_inputs:
@@ -838,9 +819,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         scheduler_output: "SchedulerOutput",
     ) -> List[torch.Tensor]:
         encoder_outputs: List[torch.Tensor] = []
-        num_reqs = self.input_batch.num_reqs
-        for req_id in self.input_batch.req_ids[:num_reqs]:
-            assert req_id is not None
+        for req_id in self.input_batch.req_ids:
             num_scheduled_tokens = scheduler_output.num_scheduled_tokens[
                 req_id]
             req_state = self.requests[req_id]
@@ -882,7 +861,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         scheduler_output: "SchedulerOutput",
         intermediate_tensors: Optional[IntermediateTensors] = None,
     ) -> Union[ModelRunnerOutput, torch.Tensor]:
-        batch_changed = self._update_states(scheduler_output)
+        self._update_states(scheduler_output)
 
         if self.is_multimodal_model:
             # Run the multimodal encoder if any.
@@ -964,8 +943,8 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         logits = self.model.compute_logits(sample_hidden_states, None)
 
         # Sample the next token and get logprobs if needed.
-        sampling_metadata = self._prepare_sampling(
-            batch_changed, scheduler_output.scheduled_spec_decode_tokens)
+        sampling_metadata = self.input_batch.get_sampling_metadata(
+            scheduler_output.scheduled_spec_decode_tokens)
         sampler_output = self.model.sample(
             logits=logits,
             sampling_metadata=sampling_metadata,
@@ -973,14 +952,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
 
         # TODO(woosuk): The following loop can be slow since it iterates over
         # the requests one by one. Optimize.
-        num_reqs = self.input_batch.num_reqs
-        req_ids: List[str] = []
-        # Because `input_batch.req_ids` is a list of length `max_num_reqs`,
-        # we need to stop at `num_reqs`.
-        # FIXME(woosuk): This is hacky. Refactor.
-        for i, req_id in zip(range(num_reqs), self.input_batch.req_ids):
-            assert req_id is not None
-            req_ids.append(req_id)
+        for i, req_id in enumerate(self.input_batch.req_ids):
             req_state = self.requests[req_id]
             seq_len = (req_state.num_computed_tokens +
                        scheduler_output.num_scheduled_tokens[req_id])
@@ -1027,7 +999,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
                 valid_sampled_token_ids)
 
         model_runner_output = ModelRunnerOutput(
-            req_ids=req_ids,
+            req_ids=self.input_batch.req_ids,
             req_id_to_index=self.input_batch.req_id_to_index,
             sampled_token_ids=valid_sampled_token_ids,
             spec_token_ids=spec_token_ids,
@@ -1041,19 +1013,18 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         sampled_token_ids: List[List[int]],
     ) -> List[List[int]]:
         # TODO(woosuk): Optimize.
-        num_reqs = len(sampled_token_ids)
         draft_token_ids: List[List[int]] = []
-        for i in range(num_reqs):
-            if len(sampled_token_ids[i]) == 0:
+        for i, sampled_ids in enumerate(sampled_token_ids):
+            num_sampled_ids = len(sampled_ids)
+            if not num_sampled_ids:
                 # Skip speculative decoding.
                 draft_token_ids.append([])
                 continue
 
             # Add sampled_token_ids to token_ids_cpu.
             start_idx = self.input_batch.num_tokens_no_spec[i]
-            end_idx = start_idx + len(sampled_token_ids[i])
-            self.input_batch.token_ids_cpu[
-                i, start_idx:end_idx] = sampled_token_ids[i]
+            end_idx = start_idx + num_sampled_ids
+            self.input_batch.token_ids_cpu[i, start_idx:end_idx] = sampled_ids
             drafter_output = self.drafter.propose(
                 self.input_batch.token_ids_cpu[i, :end_idx],
                 self.speculative_config.ngram_prompt_lookup_min,
@@ -1204,7 +1175,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         # multiplying the list, to avoid Dynamo from treating them as
         # tensor aliasing.
         dummy_kv_caches = [
-            torch.tensor([], dtype=torch.float32, device=self.device)
+            torch.tensor((), dtype=torch.float32, device=self.device)
             for _ in range(self.num_attn_layers)
         ]
 

vllm/v1/worker/tpu_model_runner.py

@@ -1048,8 +1048,6 @@ def swap_positions(b: InputBatch, id_1, id_2):
 
     b.min_tokens[id_1], b.min_tokens[id_2] = b.min_tokens[id_2], b.min_tokens[
         id_1]
-    b.stop_token_ids[id_1], b.stop_token_ids[id_2] = b.stop_token_ids[
-        id_2], b.stop_token_ids[id_1]
 
     gen_1 = b.generators.pop(id_1, None)
     gen_2 = b.generators.pop(id_2, None)