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enginex-bi_series-vllm/vllm/worker/worker.py

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2025-08-07 07:25:16 +00:00
"""A GPU worker class."""
import gc
import os
from typing import Dict, List, Tuple, Set, Optional
import torch
import torch.distributed
from vllm.config import (CacheConfig, DeviceConfig, ModelConfig,
ParallelConfig, SchedulerConfig, LoRAConfig)
from vllm.model_executor import set_random_seed
from vllm.model_executor.parallel_utils import cupy_utils
from vllm.model_executor.parallel_utils.communication_op import (
broadcast_tensor_dict)
from vllm.model_executor.parallel_utils.custom_all_reduce import init_custom_ar
from vllm.model_executor.parallel_utils.parallel_state import (
ensure_model_parallel_initialized)
from vllm.sequence import SamplerOutput, SequenceGroupMetadata
from vllm.worker.cache_engine import CacheEngine
from vllm.worker.model_runner import ModelRunner
from vllm.lora.request import LoRARequest
from vllm.utils import is_hip
class Worker:
"""A worker class that executes (a partition of) the model on a GPU.
Each worker is associated with a single GPU. The worker is responsible for
maintaining the KV cache and executing the model on the GPU. In case of
distributed inference, each worker is assigned a partition of the model.
"""
def __init__(
self,
model_config: ModelConfig,
parallel_config: ParallelConfig,
scheduler_config: SchedulerConfig,
device_config: DeviceConfig,
local_rank: int,
rank: int,
distributed_init_method: str,
lora_config: Optional[LoRAConfig] = None,
kv_cache_dtype: Optional[str] = "auto",
is_driver_worker: bool = False,
) -> None:
self.model_config = model_config
self.parallel_config = parallel_config
self.scheduler_config = scheduler_config
self.device_config = device_config
self.local_rank = local_rank
self.rank = rank
self.distributed_init_method = distributed_init_method
self.lora_config = lora_config
self.is_driver_worker = is_driver_worker
if self.is_driver_worker:
assert self.rank == 0, "The driver worker must have rank 0."
self.model_runner = ModelRunner(model_config,
parallel_config,
scheduler_config,
device_config,
lora_config=self.lora_config,
kv_cache_dtype=kv_cache_dtype,
is_driver_worker=False)
# TODO align
"""
self.model_runner = ModelRunner(model_config,
parallel_config,
scheduler_config,
device_config,
lora_config=self.lora_config,
kv_cache_dtype=kv_cache_dtype,
is_driver_worker=is_driver_worker)
"""
# Uninitialized cache engine. Will be initialized by
# self.init_cache_engine().
self.cache_config = None
self.cache_engine = None
self.cache_events = None
self.gpu_cache = None
def init_model(self, cupy_port: Optional[int] = None) -> None:
if self.device_config.device.type == "cuda":
# torch.distributed.all_reduce does not free the input tensor until
# the synchronization point. This causes the memory usage to grow
# as the number of all_reduce calls increases. This env var disables
# this behavior.
# Related issue:
# https://discuss.pytorch.org/t/cuda-allocation-lifetime-for-inputs-to-distributed-all-reduce/191573
os.environ["TORCH_NCCL_AVOID_RECORD_STREAMS"] = "1"
# This env var set by Ray causes exceptions with graph building.
os.environ.pop("NCCL_ASYNC_ERROR_HANDLING", None)
self.device = torch.device(f"cuda:{self.local_rank}")
torch.cuda.set_device(self.device)
_check_if_gpu_supports_dtype(self.model_config.dtype)
torch.cuda.empty_cache()
self.init_gpu_memory = torch.cuda.mem_get_info()[0]
else:
raise RuntimeError(
f"Not support device type: {self.device_config.device}")
# Initialize the distributed environment.
init_distributed_environment(self.parallel_config, self.rank,
cupy_port, self.distributed_init_method)
# Initialize the model.
set_random_seed(self.model_config.seed)
def load_model(self):
self.model_runner.load_model()
@torch.inference_mode()
def profile_num_available_blocks(
self,
block_size: int,
gpu_memory_utilization: float,
cpu_swap_space: int,
cache_dtype: str,
) -> Tuple[int, int]:
"""Profiles the peak memory usage of the model and returns the maximum
number of GPU and CPU cache blocks that can be allocated.
Args:
block_size: The size of the cache block.
gpu_memory_utilization: The fraction of the total GPU memory to use.
cpu_swap_space: The size of the CPU swap space in bytes.
"""
# Profile the memory usage of the model and get the maximum number of
# cache blocks that can be allocated with the remaining free memory.
torch.cuda.empty_cache()
# Execute a forward pass with dummy inputs to profile the memory usage
# of the model.
self.model_runner.profile_run()
# Calculate the number of blocks that can be allocated with the
# profiled peak memory.
torch.cuda.synchronize()
free_gpu_memory, total_gpu_memory = torch.cuda.mem_get_info()
# NOTE(woosuk): Here we assume that the other processes using the same
# GPU did not change their memory usage during the profiling.
peak_memory = self.init_gpu_memory - free_gpu_memory
cache_block_size = CacheEngine.get_cache_block_size(
block_size, cache_dtype, self.model_config, self.parallel_config)
num_gpu_blocks = int(
(total_gpu_memory * gpu_memory_utilization - peak_memory) //
cache_block_size)
num_cpu_blocks = int(cpu_swap_space // cache_block_size)
num_gpu_blocks = max(num_gpu_blocks, 0)
num_cpu_blocks = max(num_cpu_blocks, 0)
if self.model_runner.lora_manager:
self.model_runner.remove_all_loras()
gc.collect()
torch.cuda.empty_cache()
return num_gpu_blocks, num_cpu_blocks
def init_cache_engine(self, cache_config: CacheConfig) -> None:
self.cache_config = cache_config
self.cache_engine = CacheEngine(self.cache_config, self.model_config,
self.parallel_config)
self.cache_events = self.cache_engine.events
self.gpu_cache = self.cache_engine.gpu_cache
self.model_runner.set_block_size(self.cache_engine.block_size)
def warm_up_model(self) -> None:
if not self.model_config.enforce_eager:
self.model_runner.capture_model(self.gpu_cache)
# Reset the seed to ensure that the random state is not affected by
# the model initialization and profiling.
set_random_seed(self.model_config.seed)
def cache_swap(
self,
blocks_to_swap_in: Dict[int, int],
blocks_to_swap_out: Dict[int, int],
blocks_to_copy: Dict[int, List[int]],
) -> None:
# Issue cache operations.
issued_cache_op = False
if blocks_to_swap_in:
self.cache_engine.swap_in(blocks_to_swap_in)
issued_cache_op = True
if blocks_to_swap_out:
self.cache_engine.swap_out(blocks_to_swap_out)
issued_cache_op = True
if blocks_to_copy:
self.cache_engine.copy(blocks_to_copy)
issued_cache_op = True
cache_events = self.cache_events if issued_cache_op else None
# Wait for cache operations to finish.
# TODO(woosuk): Profile swapping overhead and optimize if needed.
if cache_events is not None:
for event in cache_events:
event.wait()
@torch.inference_mode()
def execute_model(
self,
seq_group_metadata_list: Optional[List[SequenceGroupMetadata]] = None,
blocks_to_swap_in: Optional[Dict[int, int]] = None,
blocks_to_swap_out: Optional[Dict[int, int]] = None,
blocks_to_copy: Optional[Dict[int, List[int]]] = None,
) -> Optional[SamplerOutput]:
# Issue cache operations.
issued_cache_op = False
if blocks_to_swap_in:
self.cache_engine.swap_in(blocks_to_swap_in)
issued_cache_op = True
if blocks_to_swap_out:
self.cache_engine.swap_out(blocks_to_swap_out)
issued_cache_op = True
if blocks_to_copy:
self.cache_engine.copy(blocks_to_copy)
issued_cache_op = True
cache_events = self.cache_events if issued_cache_op else None
# Wait for cache operations to finish.
# TODO(woosuk): Profile swapping overhead and optimize if needed.
if cache_events is not None:
for event in cache_events:
event.wait()
# If there is no input, we don't need to execute the model.
if not seq_group_metadata_list:
return {}
output = self.model_runner.execute_model(seq_group_metadata_list,
self.gpu_cache)
return output
# TODO align
"""
@torch.inference_mode()
def execute_model(
self,
seq_group_metadata_list: Optional[List[SequenceGroupMetadata]] = None,
blocks_to_swap_in: Optional[Dict[int, int]] = None,
blocks_to_swap_out: Optional[Dict[int, int]] = None,
blocks_to_copy: Optional[Dict[int, List[int]]] = None,
) -> Optional[SamplerOutput]:
if self.is_driver_worker:
assert seq_group_metadata_list is not None
num_seq_groups = len(seq_group_metadata_list)
assert blocks_to_swap_in is not None
assert blocks_to_swap_out is not None
assert blocks_to_copy is not None
data = {
"num_seq_groups": num_seq_groups,
"blocks_to_swap_in": blocks_to_swap_in,
"blocks_to_swap_out": blocks_to_swap_out,
"blocks_to_copy": blocks_to_copy,
}
broadcast_tensor_dict(data, src=0)
else:
data = broadcast_tensor_dict(src=0)
num_seq_groups = data["num_seq_groups"]
blocks_to_swap_in = data["blocks_to_swap_in"]
blocks_to_swap_out = data["blocks_to_swap_out"]
blocks_to_copy = data["blocks_to_copy"]
self.cache_swap(blocks_to_swap_in, blocks_to_swap_out, blocks_to_copy)
# If there is no input, we don't need to execute the model.
if num_seq_groups == 0:
return {}
output = self.model_runner.execute_model(seq_group_metadata_list,
self.gpu_cache)
return output
"""
def add_lora(self, lora_request: LoRARequest) -> bool:
return self.model_runner.add_lora(lora_request)
def remove_lora(self, lora_id: int) -> bool:
return self.model_runner.remove_lora(lora_id)
def list_loras(self) -> Set[int]:
return self.model_runner.list_loras()
def init_distributed_environment(
parallel_config: ParallelConfig,
rank: int,
cupy_port: Optional[int],
distributed_init_method: Optional[str] = None,
) -> None:
"""Initialize the distributed environment."""
if torch.distributed.is_initialized():
torch_world_size = torch.distributed.get_world_size()
if torch_world_size != parallel_config.world_size:
raise RuntimeError(
"torch.distributed is already initialized but the torch world "
"size does not match parallel_config.world_size "
f"({torch_world_size} vs. {parallel_config.world_size}).")
elif not distributed_init_method:
raise ValueError(
"distributed_init_method must be set if torch.distributed "
"is not already initialized")
else:
torch.distributed.init_process_group(
backend="nccl",
world_size=parallel_config.world_size,
rank=rank,
init_method=distributed_init_method,
)
if cupy_utils.is_initialized():
cupy_world_size = cupy_utils.get_world_size()
if cupy_world_size != parallel_config.world_size:
raise RuntimeError(
"cupy.distributed is already initialized but the cupy world "
"size does not match parallel_config.world_size "
f"({cupy_world_size} vs. {parallel_config.world_size}).")
elif (parallel_config.world_size > 1 and cupy_port is not None
and not is_hip()):
# NOTE(woosuk): We don't initialize CuPy process group when world size
# is 1.
# TODO(woosuk): Support multi-node connection.
cupy_utils.init_process_group(
world_size=parallel_config.world_size,
rank=rank,
host="localhost",
port=cupy_port,
)
# A small all_reduce for warmup.
torch.distributed.all_reduce(torch.zeros(1).cuda())
if cupy_utils.is_initialized():
cupy_utils.all_reduce(torch.zeros(1).cuda())
ensure_model_parallel_initialized(parallel_config.tensor_parallel_size,
parallel_config.pipeline_parallel_size)
# Initialize a custom fast all-reduce implementation.
if not parallel_config.disable_custom_all_reduce:
init_custom_ar()
def _check_if_gpu_supports_dtype(torch_dtype: torch.dtype):
# Check if the GPU supports the dtype.
if torch_dtype == torch.bfloat16:
return # avoid capability error
compute_capability = torch.cuda.get_device_capability()
if compute_capability[0] < 8:
gpu_name = torch.cuda.get_device_name()
raise ValueError(
"Bfloat16 is only supported on GPUs with compute capability "
f"of at least 8.0. Your {gpu_name} GPU has compute capability "
f"{compute_capability[0]}.{compute_capability[1]}. "
"You can use float16 instead by explicitly setting the"
"`dtype` flag in CLI, for example: --dtype=half.")