vllm/vllm/compilation/decorators.py

174 lines
6.8 KiB
Python

import inspect
from typing import Dict, List, Optional, Union
import torch
import vllm.envs as envs
from vllm.compilation.levels import CompilationLevel
from vllm.compilation.wrapper import TorchCompileWrapperWithCustomDispatcher
from vllm.logger import init_logger
from vllm.sequence import IntermediateTensors
from vllm.utils import supports_dynamo
logger = init_logger(__name__)
def support_torch_compile(
cls: Optional[type] = None,
dynamic_arg_dims: Optional[Dict[str, Union[int, List[int]]]] = None):
"""
A decorator to add support for compiling the forward method of a class.
Usage 1: use directly as a decorator without arguments:
```python
@support_torch_compile
class MyModel(nn.Module):
def forward(self, x: torch.Tensor, y: Optional[torch.Tensor]):
...
```
Usage 2: use as a decorator with arguments:
```python
@support_torch_compile(dynamic_arg_dims={"x": 0, "y": 0})
class MyModel(nn.Module):
def forward(self, x: torch.Tensor, y: Optional[torch.Tensor]):
...
```
`dynamic_arg_dims` is a dictionary that maps argument names to the dynamic
dimensions of the argument. The dynamic dimensions can be either a single
integer or a list of integers.
if `dynamic_arg_dims` is `None`, it is inferred from the type annotation
of the `forward` method, based on the following default rules:
- if the argument is annotated as `torch.Tensor` or
`Optional[torch.Tensor]`, the first dimension will be
marked as dynamic.
- if the argument is annotated as `IntermediateTensors`, the first
dimension of all the tensors in the intermediate tensors
will be marked as dynamic.
During runtime, when we actually mark dimensions of tensors,
it depends on the value of arguments:
- if it is a single integer, the corresponding dimension of the argument
will be marked as dynamic.
- if it is `None`, ignored.
- if it is `IntermediateTensors`, all the tensors in the intermediate
tensors will be marked as dynamic.
- otherwise, it will raise an error.
NOTE: if an argument is `None`, it should always be passed as `None` during
the lifetime of the model, otherwise, it cannot be captured as a single
computation graph.
"""
def cls_decorator_helper(cls: type):
# helper to pass `dynamic_arg_dims`` to `_support_torch_compile``
# to avoid too much indentation for `_support_torch_compile``
if not hasattr(cls, 'forward'):
raise TypeError("decorated class should have a forward method.")
sig = inspect.signature(cls.forward)
inferred_dynamic_arg_dims = dynamic_arg_dims
if inferred_dynamic_arg_dims is None:
inferred_dynamic_arg_dims = {}
for k, v in sig.parameters.items():
if v.annotation in [
torch.Tensor, Optional[torch.Tensor],
IntermediateTensors, Optional[IntermediateTensors]
]:
inferred_dynamic_arg_dims[k] = 0
logger.debug(("Inferred dynamic dimensions for "
"forward method of %s: %s"), cls,
list(inferred_dynamic_arg_dims.keys()))
if len(inferred_dynamic_arg_dims) == 0:
raise ValueError(
"No dynamic dimensions found in the forward method of "
f"{cls}. Please provide dynamic_arg_dims explicitly.")
for k in inferred_dynamic_arg_dims:
if k not in sig.parameters:
raise ValueError(
f"Argument {k} not found in the forward method of {cls}")
return _support_torch_compile(cls, inferred_dynamic_arg_dims)
if cls is not None:
# use `support_torch_compile` as a decorator without arguments
assert isinstance(cls, type)
return cls_decorator_helper(cls)
return cls_decorator_helper
def _support_torch_compile(cls: type,
dynamic_arg_dims: Dict[str, Union[int, List[int]]]):
"""
A decorator to add support for compiling the forward method of a class.
"""
# for CompilationLevel.DYNAMO_AS_IS , the upper level model runner
# will handle the compilation, so we don't need to do anything here.
if envs.VLLM_TORCH_COMPILE_LEVEL in [
CompilationLevel.NO_COMPILATION, CompilationLevel.DYNAMO_AS_IS
] or not supports_dynamo():
return cls
# take care of method resolution order
# make sure super().__init__ is called on the base class
# other than TorchCompileWrapperWithCustomDispatcher
cls.__bases__ = cls.__bases__ + (TorchCompileWrapperWithCustomDispatcher, )
old_init = cls.__init__ # type: ignore
def __init__(self, *args, **kwargs):
old_init(self, *args, **kwargs)
TorchCompileWrapperWithCustomDispatcher.__init__(self)
cls.__init__ = __init__ # type: ignore
def __call__(self, *args, **kwargs):
# torch.compiler.is_compiling() means we are inside the compilation
# e.g. TPU has the compilation logic in model runner, so we don't
# need to compile the model inside.
if torch.compiler.is_compiling():
return self.forward(*args, **kwargs)
# the first compilation needs to have dynamic shapes marked
if len(self.compiled_codes) < 1:
sig = inspect.signature(self.__class__.forward)
bound_args = sig.bind(self, *args, **kwargs)
bound_args.apply_defaults()
for k, dims in dynamic_arg_dims.items():
arg = bound_args.arguments.get(k)
if arg is not None:
if isinstance(arg, torch.Tensor):
torch._dynamo.mark_dynamic(arg, dims)
elif isinstance(arg, IntermediateTensors):
for tensor in arg.tensors.values():
torch._dynamo.mark_dynamic(tensor, dims)
else:
raise ValueError(
"Unsupported dynamic dimensions"
f" {dims} for argument {k} with type {type(arg)}.")
# if we don't use custom dispatcher, we can directly call the
# compiled function and let torch.compile handle the dispatching,
# with the overhead of guard evaluation and recompilation.
if len(self.compiled_codes) < 1 or not self.use_custom_dispatcher:
return self.compiled_callable(*args, **kwargs)
# usually, capturing the model once is enough, and then we can
# dispatch to the compiled code directly, without going through
# the Dynamo guard mechanism.
with self.dispatch_to_code(0):
model_output = self.forward(*args, **kwargs)
return model_output
cls.__call__ = __call__ # type: ignore
return cls