[core] clean up cudagraph batchsize padding logic

tests/models/decoder_only/language/test_jamba.py

@@ -1,7 +1,7 @@
 import pytest
 
 from tests.utils import multi_gpu_test
-from vllm.config import VllmConfig
+from vllm.engine.arg_utils import EngineArgs
 from vllm.sampling_params import SamplingParams
 
 from ...utils import check_outputs_equal
@@ -189,7 +189,8 @@ def test_mamba_cache_cg_padding(
     # This test is for verifying that mamba cache is padded to CG captured
     # batch size. If it's not, a torch RuntimeError will be raised because
     # tensor dimensions aren't compatible
-    while len(example_prompts) == VllmConfig.get_graph_batch_size(
+    vllm_config = EngineArgs(model=model).create_engine_config()
+    while len(example_prompts) == vllm_config.pad_for_cudagraph(
             len(example_prompts)):
         example_prompts.append(example_prompts[0])
 

tests/models/decoder_only/language/test_mamba.py

@@ -5,7 +5,7 @@
 import pytest
 from transformers import AutoModelForCausalLM, AutoTokenizer
 
-from vllm.config import VllmConfig
+from vllm.engine.arg_utils import EngineArgs
 from vllm.sampling_params import SamplingParams
 
 from ...utils import check_outputs_equal
@@ -200,7 +200,8 @@ def test_mamba_cache_cg_padding(
     # This test is for verifying that mamba cache is padded to CG captured
     # batch size. If it's not, a torch RuntimeError will be raised because
     # tensor dimensions aren't compatible
-    while len(example_prompts) == VllmConfig.get_graph_batch_size(
+    vllm_config = EngineArgs(model=model).create_engine_config()
+    while len(example_prompts) == vllm_config.pad_for_cudagraph(
             len(example_prompts)):
         example_prompts.append(example_prompts[0])
 

tests/worker/test_encoder_decoder_model_runner.py

@@ -4,7 +4,6 @@
 import pytest
 import torch
 
-from vllm.config import VllmConfig
 from vllm.engine.arg_utils import EngineArgs
 from vllm.platforms import current_platform
 from vllm.sequence import SamplingParams, SequenceData, SequenceGroupMetadata
@@ -548,7 +547,8 @@ def test_prepare_decode_cuda_graph(batch_size, multiple_seqs_per_seq_group):
     # With CUDA Graph capture and replay enabled, the decoder and encoder
     # input sequences will be padded. Create the expected padded tensors
     # accordingly.
-    graph_batch_size = VllmConfig.get_graph_batch_size(expanded_batch_size)
+    graph_batch_size = model_runner.vllm_config.pad_for_cudagraph(
+        expanded_batch_size)
     cuda_graph_pad_size = graph_batch_size - expanded_batch_size
     padded_seq_lens = seq_lens + list(itertools.repeat(1, cuda_graph_pad_size))
     padded_encoder_seq_lens = encoder_seq_lens + list(

tests/worker/test_model_runner.py

@@ -3,7 +3,6 @@
 import pytest
 import torch
 
-from vllm.config import VllmConfig
 from vllm.distributed.parallel_state import (ensure_model_parallel_initialized,
                                              init_distributed_environment)
 from vllm.engine.arg_utils import EngineArgs
@@ -177,7 +176,8 @@ def test_prepare_decode_cuda_graph(batch_size):
         model_input.attn_metadata, model_input.attn_metadata.slot_mapping)
     assert len(slot_mapping) == len(input_tokens)
 
-    expected_bs = VllmConfig.get_graph_batch_size(len(seq_group_metadata_list))
+    expected_bs = model_runner.vllm_config.pad_for_cudagraph(
+        len(seq_group_metadata_list))
     # Verify input metadata is correct for prompts.
     device = model_runner.device
     assert attn_metadata.num_prefills == 0

vllm/config.py

@@ -2354,6 +2354,12 @@ def model_post_init(self, __context: Any) -> None:
     # not configurable, computed after init
     compile_sizes: List[int] = PrivateAttr
     capture_sizes: List[int] = PrivateAttr
+    max_capture_size: int = PrivateAttr
+    # optimization:
+    # Intuitively, bs_to_padded_graph_size should be Dict[int, int].
+    # since we know all keys are in a range [0, max_capture_size],
+    # we can optimize it to List[int] for better lookup performance.
+    bs_to_padded_graph_size: List[int] = PrivateAttr
 
     # keep track of enabled and disabled custom ops
     enabled_custom_ops: Counter[str] = PrivateAttr
@@ -2365,6 +2371,19 @@ def model_post_init(self, __context: Any) -> None:
     # Map from layer name to the attention cls
     static_forward_context: Dict[str, Any] = PrivateAttr
 
+    def __repr__(self) -> str:
+        exclude = {
+            "static_forward_context",
+            "enabled_custom_ops",
+            "disabled_custom_ops",
+            "compilation_time",
+            "bs_to_padded_graph_size",
+            "pass_config",
+        }
+        return self.model_dump_json(exclude=exclude, exclude_unset=True)
+
+    __str__ = __repr__
+
     @classmethod
     def from_cli(cls, cli_value: str) -> "CompilationConfig":
         """Parse the CLI value for the compilation config."""
@@ -2450,18 +2469,22 @@ def init_with_cudagraph_sizes(self, sizes_to_specialize: List[int]):
 
         # sort to make sure cudagraph capture sizes are in descending order
         self.capture_sizes.sort(reverse=True)
+        self.max_capture_size = self.capture_sizes[
+            0] if self.capture_sizes else 0
 
-
-_BATCH_SIZE_ALIGNMENT = 8
-# all the token sizes that **can** be captured by cudagraph.
-# they can be arbitrarily large.
-# currently it includes: 1, 2, 4, 8, 16, 24, 32, 40, ..., 8192.
-# the actual sizes to capture will be determined by the model,
-# depending on the model's max_num_seqs.
-# NOTE: get_graph_batch_size needs to be updated if this list is changed.
-_BATCH_SIZES_TO_CAPTURE = [1, 2, 4] + [
-    _BATCH_SIZE_ALIGNMENT * i for i in range(1, 1025)
-]
+        # pre-compute the mapping from batch size to padded graph size
+        self.bs_to_padded_graph_size = [
+            0 for i in range(self.max_capture_size + 1)
+        ]
+        for end, start in zip(self.capture_sizes,
+                              self.capture_sizes[1:] + [0]):
+            for bs in range(start, end):
+                if bs == start:
+                    self.bs_to_padded_graph_size[bs] = start
+                else:
+                    self.bs_to_padded_graph_size[bs] = end
+        self.bs_to_padded_graph_size[
+            self.max_capture_size] = self.max_capture_size
 
 
 @dataclass
@@ -2491,40 +2514,10 @@ class VllmConfig:
                                                  init=True)  # type: ignore
     instance_id: str = ""
 
-    @staticmethod
-    def get_graph_batch_size(batch_size: int) -> int:
-        """Returns the padded batch size given actual batch size.
-
-        Batch sizes are 1, 2, 4, _BATCH_SIZE_ALIGNMENT,
-        2*_BATCH_SIZE_ALIGNMENT, 3*_BATCH_SIZE_ALIGNMENT...
-        """
-        if batch_size <= 2:
-            return batch_size
-        elif batch_size <= 4:
-            return 4
-        else:
-            return ((batch_size + _BATCH_SIZE_ALIGNMENT - 1) //
-                    _BATCH_SIZE_ALIGNMENT * _BATCH_SIZE_ALIGNMENT)
-
-    @staticmethod
-    def get_max_graph_batch_size(max_num_seqs: int) -> int:
-        """
-        max_num_seqs: Maximum number of sequences in a batch.
-        _BATCH_SIZES_TO_CAPTURE: all the sizes that we want to capture.
-
-        pad the max_num_seqs if necessary by calling get_graph_batch_size,
-        which will deal with some edge cases like 1, 2, 4.
-
-        if the padded size is in _BATCH_SIZES_TO_CAPTURE, return the padded
-        size. if not, it means the padded size is larger than the largest size
-        in _BATCH_SIZES_TO_CAPTURE, return the largest size in
-        _BATCH_SIZES_TO_CAPTURE.
-        """
-        padded_size = VllmConfig.get_graph_batch_size(max_num_seqs)
-        if padded_size in _BATCH_SIZES_TO_CAPTURE:
-            return padded_size
-        assert padded_size > _BATCH_SIZES_TO_CAPTURE[-1]
-        return _BATCH_SIZES_TO_CAPTURE[-1]
+    def pad_for_cudagraph(self, batch_size: int) -> int:
+        if batch_size > self.compilation_config.max_capture_size:
+            return self.compilation_config.max_capture_size
+        return self.compilation_config.bs_to_padded_graph_size[batch_size]
 
     @staticmethod
     def _get_quantization_config(
@@ -2618,27 +2611,7 @@ def __post_init__(self):
             self.compilation_config.pass_config.enable_reshape = False
             self.compilation_config.level = CompilationLevel.PIECEWISE
 
-        if not envs.VLLM_USE_V1:
-            max_batchsize_to_capture = 0
-            if self.scheduler_config is not None and \
-                self.model_config is not None and \
-                    not self.model_config.enforce_eager:
-                max_batchsize_to_capture = \
-                    self.get_max_graph_batch_size(
-                    self.scheduler_config.max_num_seqs)
-            batch_size_capture_list = [
-                size for size in _BATCH_SIZES_TO_CAPTURE
-                if size <= max_batchsize_to_capture
-            ]
-        else:
-            batch_size_capture_list = []
-            if self.model_config is not None and \
-                not self.model_config.enforce_eager:
-                batch_size_capture_list = [1, 2, 4
-                                           ] + [i for i in range(8, 513, 8)]
-
-        self.compilation_config.init_with_cudagraph_sizes(
-            batch_size_capture_list)
+        self._set_cudagraph_sizes()
 
         if self.cache_config is not None and \
             self.cache_config.cpu_offload_gb > 0 and \
@@ -2659,6 +2632,70 @@ def __post_init__(self):
         if not self.instance_id:
             self.instance_id = random_uuid()[:5]
 
+    def _set_cudagraph_sizes(self):
+        """
+        cudagraph batchsize padding logic:
+
+        `[1, 2, 4] + [8 * i for i in range(1, 1025)]` is a list of all possible
+        batch sizes that cudagraph will capture.
+
+        Depending on the engine's configuration of `max_num_seqs`, the
+        candidate batch sizes to capture cudagraph will shrink to the subset
+        which just cover the range of `[1, max_num_seqs]`. In the common case,
+        `max_num_seqs` is 256, and the cudagraph batch sizes will be
+        `[1, 2, 4, 8, 16, 24, 32, 40, ..., 256]`.
+
+        However, if users specify the cudagraph capture sizes through
+        compilation config, we will use the specified sizes instead.
+
+        In the end, `vllm_config.compilation_config.capture_sizes` will be the
+        final sizes to capture cudagraph (in descending order).
+
+        During runtime, if batchsize is larger than
+        `vllm_config.compilation_config.capture_sizes`,
+        no cudagraph will be used.
+        If the batch size is no larger than
+        `vllm_config.compilation_config.capture_sizes`,
+        we can quickly find the padded graph size for a given batch size by
+        looking up `vllm_config.compilation_config.bs_to_padded_graph_size`.
+        """
+
+        # calculate the default `batch_size_capture_list`
+        if not envs.VLLM_USE_V1:
+            batch_size_capture_list = []
+            max_batchsize_to_capture = 0
+            if self.scheduler_config is not None and \
+                self.model_config is not None and \
+                    not self.model_config.enforce_eager:
+
+                possible_sizes = [1, 2, 4] + [8 * i for i in range(1, 1025)]
+                # find the minimum size that is larger than max_num_seqs,
+                # which then becomes the max_batchsize_to_capture
+                larger_sizes = [
+                    x for x in possible_sizes
+                    if x >= self.scheduler_config.max_num_seqs
+                ]
+                if larger_sizes:
+                    max_batchsize_to_capture = larger_sizes[0]
+                else:
+                    max_batchsize_to_capture = possible_sizes[-1]
+
+                # filter out the sizes that are
+                # larger than max_batchsize_to_capture
+                batch_size_capture_list = [
+                    size for size in possible_sizes
+                    if size <= max_batchsize_to_capture
+                ]
+        else:
+            batch_size_capture_list = []
+            if self.model_config is not None and \
+                not self.model_config.enforce_eager:
+                batch_size_capture_list = [1, 2, 4
+                                           ] + [i for i in range(8, 513, 8)]
+
+        self.compilation_config.init_with_cudagraph_sizes(
+            batch_size_capture_list)
+
     def __str__(self):
         return (
             f"model={self.model_config.model!r},"

vllm/model_executor/models/jamba.py

@@ -7,7 +7,7 @@
 
 from vllm.attention.backends.abstract import AttentionMetadata
 from vllm.attention.layer import Attention
-from vllm.config import _BATCH_SIZES_TO_CAPTURE, CacheConfig, VllmConfig
+from vllm.config import CacheConfig, VllmConfig
 from vllm.distributed import get_tensor_model_parallel_world_size
 from vllm.distributed.parallel_state import get_pp_group
 from vllm.model_executor.layers.fused_moe import FusedMoE
@@ -420,6 +420,9 @@ def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
 
         self.make_empty_intermediate_tensors = (
             self.model.make_empty_intermediate_tensors)
+        self.max_batch_size = (vllm_config.pad_for_cudagraph(
+            self.scheduler_config.max_num_seqs)
+                               if self.scheduler_config else 8192 + 2)
 
     def get_input_embeddings(self, input_ids: torch.Tensor) -> torch.Tensor:
         return self.model.get_input_embeddings(input_ids)
@@ -433,15 +436,12 @@ def forward(self,
                 inputs_embeds: Optional[torch.Tensor] = None,
                 **kwargs):
         if self.mamba_cache is None:
-            max_batch_size = (VllmConfig.get_graph_batch_size(
-                self.scheduler_config.max_num_seqs) if self.scheduler_config
-                              else max(_BATCH_SIZES_TO_CAPTURE) + 2)
 
             num_mamba_layers = self.model_config.get_num_layers_by_block_type(
                 self.vllm_config.parallel_config, LayerBlockType.mamba)
             self.mamba_cache = MambaCacheManager(
-                self.lm_head.weight.dtype, num_mamba_layers, max_batch_size,
-                *self._get_mamba_cache_shape())
+                self.lm_head.weight.dtype, num_mamba_layers,
+                self.max_batch_size, *self._get_mamba_cache_shape())
         (
             mamba_cache_tensors,
             state_indices_tensor,

vllm/model_executor/models/mamba.py

@@ -6,7 +6,7 @@
 from transformers import MambaConfig
 
 from vllm.attention.backends.abstract import AttentionMetadata
-from vllm.config import _BATCH_SIZES_TO_CAPTURE, CacheConfig, VllmConfig
+from vllm.config import CacheConfig, VllmConfig
 from vllm.distributed import get_tensor_model_parallel_world_size
 from vllm.distributed.parallel_state import get_pp_group
 from vllm.model_executor.layers.layernorm import RMSNorm
@@ -195,6 +195,9 @@ def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
 
         self.make_empty_intermediate_tensors = (
             self.backbone.make_empty_intermediate_tensors)
+        self.max_batch_size = (vllm_config.pad_for_cudagraph(
+            self.scheduler_config.max_num_seqs)
+                               if self.scheduler_config else 8192 + 2)
 
     def get_input_embeddings(self, input_ids: torch.Tensor) -> torch.Tensor:
         return self.backbone.get_input_embeddings(input_ids)
@@ -208,15 +211,11 @@ def forward(self,
                 inputs_embeds: Optional[torch.Tensor] = None,
                 **kwargs):
         if self.mamba_cache is None:
-            max_batch_size = (VllmConfig.get_graph_batch_size(
-                self.scheduler_config.max_num_seqs) if self.scheduler_config
-                              else max(_BATCH_SIZES_TO_CAPTURE) + 2)
-
             num_mamba_layers = self.model_config.get_num_layers_by_block_type(
                 self.vllm_config.parallel_config, LayerBlockType.mamba)
             self.mamba_cache = MambaCacheManager(
-                self.lm_head.weight.dtype, num_mamba_layers, max_batch_size,
-                *self._get_mamba_cache_shape())
+                self.lm_head.weight.dtype, num_mamba_layers,
+                self.max_batch_size, *self._get_mamba_cache_shape())
 
         (
             mamba_cache_tensors,

vllm/v1/worker/gpu_model_runner.py

@@ -1,6 +1,6 @@
 import gc
 import time
-from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
+from typing import TYPE_CHECKING, Dict, List, Tuple
 
 import numpy as np
 import torch
@@ -459,7 +459,7 @@ def execute_model(
                 and num_scheduled_tokens <= self.cudagraph_batch_sizes[-1]):
             # Use piecewise CUDA graphs.
             # Add padding to the batch size.
-            num_input_tokens = self._get_padded_batch_size(
+            num_input_tokens = self.vllm_config.pad_for_cudagraph(
                 num_scheduled_tokens)
         else:
             # Eager mode.
@@ -641,10 +641,3 @@ def initialize_kv_cache(self, num_blocks: int) -> None:
                 torch.zeros(kv_cache_shape,
                             dtype=self.kv_cache_dtype,
                             device=self.device))
-
-    def _get_padded_batch_size(self, batch_size: int) -> Optional[int]:
-        # TODO: Optimize this?
-        for size in self.cudagraph_batch_sizes:
-            if batch_size <= size:
-                return size
-        return None

vllm/worker/enc_dec_model_runner.py

@@ -464,7 +464,7 @@ def _prepare_encoder_model_input_tensors(
                 # We will be using CUDA graph replay for this decode.
                 max_len_of_block_table = self.get_max_block_per_batch()
                 batch_size = len(encoder_seq_lens)
-                graph_batch_size = self.vllm_config.get_graph_batch_size(
+                graph_batch_size = self.vllm_config.pad_for_cudagraph(
                     batch_size)
                 assert graph_batch_size >= batch_size
                 cuda_graph_pad_size = graph_batch_size - batch_size