[Model Runner V2] Refactor CudaGraphManager (#29583)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>
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Woosuk Kwon 2025-11-26 21:37:59 -08:00 committed by GitHub
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@ -1,6 +1,7 @@
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from unittest.mock import patch
from collections.abc import Callable, Iterable
from typing import Any
import numpy as np
import torch
@ -32,6 +33,7 @@ class CudaGraphManager:
self.max_model_len = vllm_config.model_config.max_model_len
self.max_num_reqs = self.scheduler_config.max_num_seqs
self.max_num_tokens = self.scheduler_config.max_num_batched_tokens
self.dp_size = vllm_config.parallel_config.data_parallel_size
self.compilation_config = vllm_config.compilation_config
assert self.compilation_config is not None
@ -40,102 +42,60 @@ class CudaGraphManager:
self.cudagraph_mode = CUDAGraphMode.NONE
else:
self.cudagraph_mode = self.compilation_config.cudagraph_mode
if self.compilation_config.cudagraph_capture_sizes is not None:
cudagraph_sizes = sorted(self.compilation_config.cudagraph_capture_sizes)
# Limit the cudagraph sizes to the max decode batch size.
self.cudagraph_sizes = [
x for x in cudagraph_sizes if x <= self.max_num_reqs
]
else:
self.cudagraph_sizes = []
self.padded_sizes = self._init_padded_sizes()
self.cudagraph_sizes = get_cudagraph_sizes(
self.compilation_config.cudagraph_capture_sizes,
self.max_num_reqs,
self.max_num_tokens,
self.cudagraph_mode,
)
self.graphs: dict[int, torch.cuda.CUDAGraph] = {}
self.pool = torch.cuda.graph_pool_handle()
self.hidden_states: torch.Tensor | None = None
def _init_padded_sizes(self) -> dict[int, int]:
if not self.cudagraph_mode.has_full_cudagraphs():
# Full cuda graphs are not used.
return {}
if not self.cudagraph_sizes:
return {}
padded_sizes: dict[int, int] = {}
for i in range(1, self.cudagraph_sizes[-1] + 1):
for x in self.cudagraph_sizes:
if i <= x:
padded_sizes[i] = x
break
return padded_sizes
def needs_capture(self) -> bool:
return len(self.padded_sizes) > 0
return len(self.cudagraph_sizes) > 0
def get_cudagraph_size(
self,
scheduler_output: SchedulerOutput,
num_tokens_after_padding: int,
) -> int | None:
if not self.cudagraph_mode.has_full_cudagraphs():
return None
if self.cudagraph_mode != CUDAGraphMode.FULL:
# TODO(woosuk): Support uniform decode with multiple tokens (spec decoding).
all_decode = all(
x == 1 for x in scheduler_output.num_scheduled_tokens.values()
)
if not all_decode:
# Prefill is included.
return None
return self.padded_sizes.get(num_tokens_after_padding)
return get_cudagraph_size(
num_tokens_after_padding,
scheduler_output.num_scheduled_tokens.values(),
self.cudagraph_sizes,
self.cudagraph_mode,
)
def capture_graph(
self,
batch_size: int,
num_tokens: int,
model: nn.Module,
input_buffers: InputBuffers,
block_tables: BlockTables,
attn_metadata_builders: list[AttentionMetadataBuilder],
kv_cache_config: KVCacheConfig,
) -> None:
assert batch_size not in self.graphs
# Prepare dummy inputs.
input_ids = input_buffers.input_ids.gpu[:batch_size]
positions = input_buffers.positions[:batch_size]
input_buffers.query_start_loc.np[: batch_size + 1] = np.arange(batch_size + 1)
input_buffers.query_start_loc.np[batch_size:] = batch_size
input_buffers.query_start_loc.copy_to_gpu()
# HACK(woosuk): To optimize warmup time, we use 1 (instead of max_model_len)
# for seq_lens. This leads to a mismatch between seq_lens (GPU) and
# seq_lens_np (CPU), which might cause issues in some attention backends.
input_buffers.seq_lens[:batch_size] = 1
input_buffers.seq_lens[batch_size:] = 0
input_block_tables = [x[:batch_size] for x in block_tables.input_block_tables]
slot_mappings = block_tables.slot_mappings[:, :batch_size]
attn_metadata = build_attn_metadata(
attn_metadata_builders=attn_metadata_builders,
num_reqs=batch_size,
num_tokens=batch_size,
query_start_loc_gpu=input_buffers.query_start_loc.gpu[: batch_size + 1],
query_start_loc_cpu=input_buffers.query_start_loc.cpu[: batch_size + 1],
seq_lens=input_buffers.seq_lens,
seq_lens_np=np.full(batch_size, self.max_model_len, dtype=np.int32),
num_computed_tokens_cpu=None, # FIXME
block_tables=input_block_tables,
slot_mappings=slot_mappings,
kv_cache_config=kv_cache_config,
num_reqs = min(num_tokens, self.max_num_reqs)
input_ids = input_buffers.input_ids.gpu[:num_tokens]
positions = input_buffers.positions[:num_tokens]
attn_metadata = prepare_inputs_to_capture(
num_reqs,
num_tokens,
input_buffers,
block_tables,
attn_metadata_builders,
self.max_model_len,
kv_cache_config,
)
num_tokens_across_dp = make_num_tokens_across_dp(self.dp_size, batch_size)
num_tokens_across_dp = make_num_tokens_across_dp(self.dp_size, num_tokens)
# Warm up.
with set_forward_context(
attn_metadata,
self.vllm_config,
num_tokens=batch_size,
num_tokens=num_tokens,
cudagraph_runtime_mode=CUDAGraphMode.NONE,
num_tokens_across_dp=num_tokens_across_dp,
):
@ -147,13 +107,13 @@ class CudaGraphManager:
self.hidden_states = torch.empty_like(hidden_states)
# Capture the graph.
assert num_tokens not in self.graphs
graph = torch.cuda.CUDAGraph()
with (
patch("torch.cuda.empty_cache", lambda: None),
set_forward_context(
attn_metadata,
self.vllm_config,
num_tokens=batch_size,
num_tokens=num_tokens,
cudagraph_runtime_mode=CUDAGraphMode.NONE,
num_tokens_across_dp=num_tokens_across_dp,
),
@ -163,8 +123,8 @@ class CudaGraphManager:
input_ids=input_ids,
positions=positions,
)
self.hidden_states[:batch_size] = hidden_states
self.graphs[batch_size] = graph
self.hidden_states[:num_tokens] = hidden_states
self.graphs[num_tokens] = graph
@torch.inference_mode()
def capture(
@ -175,25 +135,124 @@ class CudaGraphManager:
attn_metadata_builders: list[AttentionMetadataBuilder],
kv_cache_config: KVCacheConfig,
) -> None:
assert self.needs_capture()
# Capture larger graphs first.
sizes_to_capture = sorted(self.cudagraph_sizes, reverse=True)
if is_global_first_rank():
sizes_to_capture = tqdm(sizes_to_capture, desc="Capturing CUDA graphs")
capture_graphs(
self.cudagraph_sizes,
self.device,
self.capture_graph,
model=model,
input_buffers=input_buffers,
block_tables=block_tables,
attn_metadata_builders=attn_metadata_builders,
kv_cache_config=kv_cache_config,
)
with graph_capture(device=self.device):
for batch_size in sizes_to_capture:
self.capture_graph(
batch_size,
model,
input_buffers,
block_tables,
attn_metadata_builders,
kv_cache_config,
)
def run(self, batch_size: int) -> torch.Tensor:
assert batch_size in self.graphs
self.graphs[batch_size].replay()
def run(self, num_tokens: int) -> torch.Tensor:
assert num_tokens in self.graphs
self.graphs[num_tokens].replay()
assert self.hidden_states is not None
return self.hidden_states[:batch_size]
return self.hidden_states[:num_tokens]
def get_cudagraph_sizes(
capture_sizes: list[int] | None,
max_num_reqs: int,
max_num_tokens: int,
cudagraph_mode: CUDAGraphMode,
) -> dict[int, int]:
if not cudagraph_mode.has_full_cudagraphs():
return {}
if not capture_sizes:
return {}
capture_sizes = sorted(capture_sizes)
# Limit the capture sizes to the max number of requests or tokens.
upper_bound = (
max_num_reqs
if cudagraph_mode == CUDAGraphMode.FULL_DECODE_ONLY
else max_num_tokens
)
capture_sizes = [x for x in capture_sizes if x <= upper_bound]
if not capture_sizes:
return {}
cudagraph_sizes: dict[int, int] = {}
for i in range(1, capture_sizes[-1] + 1):
for x in capture_sizes:
if i <= x:
cudagraph_sizes[i] = x
break
return cudagraph_sizes
def get_cudagraph_size(
num_tokens_after_dp_padding: int,
num_tokens_per_request: Iterable[int],
cudagraph_sizes: dict[int, int],
cudagraph_mode: CUDAGraphMode,
) -> int | None:
size = cudagraph_sizes.get(num_tokens_after_dp_padding)
if size is None:
# No CUDA graph for this size.
return None
if cudagraph_mode == CUDAGraphMode.FULL_DECODE_ONLY:
all_decode = all(x == 1 for x in num_tokens_per_request)
if not all_decode:
# Prefill is included.
return None
return size
def capture_graphs(
cudagraph_sizes: dict[int, int],
device: torch.device,
capture_fn: Callable,
**capture_kwargs,
) -> None:
# Capture larger graphs first.
sizes_to_capture = sorted(set(cudagraph_sizes.values()), reverse=True)
if is_global_first_rank():
sizes_to_capture = tqdm(sizes_to_capture, desc="Capturing CUDA graphs")
with graph_capture(device=device):
for size in sizes_to_capture:
capture_fn(size, **capture_kwargs)
def prepare_inputs_to_capture(
num_reqs: int,
num_tokens: int,
input_buffers: InputBuffers,
block_tables: BlockTables,
attn_metadata_builders: list[AttentionMetadataBuilder],
max_model_len: int,
kv_cache_config: KVCacheConfig,
) -> dict[str, Any]:
num_tokens_per_req = num_tokens // num_reqs
query_start_loc = input_buffers.query_start_loc
query_start_loc.np[: num_reqs + 1] = np.arange(num_reqs + 1) * num_tokens_per_req
query_start_loc.np[num_reqs:] = num_tokens
query_start_loc.copy_to_gpu()
seq_lens_np = np.full(num_reqs, max_model_len, dtype=np.int32)
# HACK(woosuk): To optimize warmup time, we use 1 (instead of max_model_len)
# for seq_lens. This leads to a mismatch between seq_lens (GPU) and
# seq_lens_np (CPU), which might cause issues in some attention backends.
input_buffers.seq_lens[:num_reqs] = 1
input_buffers.seq_lens[num_reqs:] = 0
input_block_tables = [x[:num_reqs] for x in block_tables.input_block_tables]
slot_mappings = block_tables.slot_mappings[:, :num_tokens]
attn_metadata = build_attn_metadata(
attn_metadata_builders=attn_metadata_builders,
num_reqs=num_reqs,
num_tokens=num_tokens,
query_start_loc_gpu=query_start_loc.gpu[: num_reqs + 1],
query_start_loc_cpu=query_start_loc.cpu[: num_reqs + 1],
seq_lens=input_buffers.seq_lens,
seq_lens_np=seq_lens_np,
num_computed_tokens_cpu=None, # FIXME
block_tables=input_block_tables,
slot_mappings=slot_mappings,
kv_cache_config=kv_cache_config,
)
return attn_metadata