vllm/vllm/compilation/compiler_interface.py
Harry Mellor 3b352a2f92
Correct capitalisation: VLLM -> vLLM (#14562)
Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
2025-03-10 16:36:21 +00:00

354 lines
14 KiB
Python

# SPDX-License-Identifier: Apache-2.0
import copy
import hashlib
import os
from contextlib import ExitStack
from typing import Any, Callable, Dict, List, Optional, Tuple
from unittest.mock import patch
import torch
import torch._inductor.compile_fx
import torch.fx as fx
from vllm.config import VllmConfig
class CompilerInterface:
"""
The interface for a compiler that can be used by vLLM.
"""
# The name of the compiler, e.g. inductor.
# This is a class-level attribute.
name: str
def initialize_cache(self, cache_dir: str, disable_cache: bool = False):
"""
when the vLLM process uses `cache_dir` as the cache directory,
the compiler should initialize itself with the cache directory,
e.g. by re-directing its own cache directory to a sub-directory.
"""
pass
def compute_hash(self, vllm_config: VllmConfig) -> str:
"""
Gather all the relevant information from the vLLM config,
to compute a hash so that we can cache the compiled model.
See :meth:`VllmConfig.compute_hash` to check what information
is already considered by default. This function should only
consider the information that is specific to the compiler.
"""
return ""
def compile(
self,
graph: fx.GraphModule,
example_inputs: List[Any],
compiler_config: Dict[str, Any],
runtime_shape: Optional[int] = None
) -> Tuple[Optional[Callable], Optional[Any]]:
"""
Compile the graph with the given example inputs and compiler config,
with a runtime shape. If the `runtime_shape` is None, it means
the `example_inputs` have a dynamic shape. Otherwise, the
`runtime_shape` specifies the shape of the inputs. Right now we only
support one variable shape for all inputs, which is the batchsize
(number of tokens) during inference.
Dynamo will make sure `graph(*example_inputs)` is valid.
The function should return a compiled callable function, as well as
a handle that can be used to directly load the compiled function.
The handle should be a plain Python object, preferably a string or a
file path for readability.
If the compiler doesn't support caching, it should return None for the
handle. If the compiler fails to compile the graph, it should return
None for the compiled function as well.
"""
return None, None
def load(self,
handle: Any,
graph: fx.GraphModule,
example_inputs: List[Any],
graph_index: int,
runtime_shape: Optional[int] = None) -> Callable:
"""
Load the compiled function from the handle.
Raises an error if the handle is invalid.
The handle is the second return value of the `compile` function.
"""
raise NotImplementedError("caching is not supported")
class AlwaysHitShapeEnv:
"""
Why do we need this class:
For normal `torch.compile` usage, every compilation will have
one Dynamo bytecode compilation and one Inductor compilation.
The Inductor compilation happens under the context of the
Dynamo bytecode compilation, and that context is used to
determine the dynamic shape information, etc.
For our use case, we only run Dynamo bytecode compilation once,
and run Inductor compilation multiple times with different shapes
plus a general shape. The compilation for specific shapes happens
outside of the context of the Dynamo bytecode compilation. At that
time, we don't have shape environment to provide to Inductor, and
it will fail the Inductor code cache lookup.
By providing a dummy shape environment that always hits, we can
make the Inductor code cache lookup always hit, and we can
compile the graph for different shapes as needed.
The following dummy methods are obtained by trial-and-error
until it works.
"""
def __init__(self) -> None:
self.guards: List[Any] = []
def evaluate_guards_expression(self, *args, **kwargs):
return True
def get_pruned_guards(self, *args, **kwargs):
return []
def produce_guards_expression(self, *args, **kwargs):
return ""
class InductorAdaptor(CompilerInterface):
"""
The adaptor for the Inductor compiler, version 2.5 and 2.6.
"""
name = "inductor"
def compute_hash(self, vllm_config: VllmConfig) -> str:
factors: List[Any] = []
# summarize system state
from torch._inductor.codecache import CacheBase
system_factors = CacheBase.get_system()
factors.append(system_factors)
# summarize pytorch state
from torch._inductor.codecache import torch_key
torch_factors = torch_key()
factors.append(torch_factors)
hash_str = hashlib.md5(str(factors).encode()).hexdigest()[:10]
return hash_str
def initialize_cache(self, cache_dir: str, disable_cache: bool = False):
if disable_cache:
return
# redirect the cache directory to a sub-directory
# set flags so that Inductor and Triton store their cache
# in the cache_dir, then users only need to copy the cache_dir
# to another machine to reuse the cache.
inductor_cache = os.path.join(cache_dir, "inductor_cache")
os.makedirs(inductor_cache, exist_ok=True)
os.environ["TORCHINDUCTOR_CACHE_DIR"] = inductor_cache
triton_cache = os.path.join(cache_dir, "triton_cache")
os.makedirs(triton_cache, exist_ok=True)
os.environ["TRITON_CACHE_DIR"] = triton_cache
self.cache_dir = cache_dir
def compile(
self,
graph: fx.GraphModule,
example_inputs: List[Any],
compiler_config: Dict[str, Any],
runtime_shape: Optional[int] = None
) -> Tuple[Optional[Callable], Optional[Any]]:
from torch._inductor import config
current_config = config.get_config_copy()
from torch._inductor.compile_fx import compile_fx
# disable remote cache
current_config["fx_graph_cache"] = True
current_config["fx_graph_remote_cache"] = False
if compiler_config is not None:
current_config.update(compiler_config)
if isinstance(runtime_shape, int):
# for a specific batchsize, tuning triton kernel parameters
# can be beneficial
current_config["max_autotune"] = True
current_config["coordinate_descent_tuning"] = True
# inductor can inplace modify the graph, so we need to copy it
# see https://github.com/pytorch/pytorch/issues/138980
graph = copy.deepcopy(graph)
# it's the first time we compile this graph
# the assumption is that we don't have nested Inductor compilation.
# compiled_fx_graph_hash will only be called once, and we can hook
# it to get the hash of the compiled graph directly.
hash_str, file_path = None, None
from torch._inductor.codecache import (FxGraphCache,
compiled_fx_graph_hash)
if torch.__version__.startswith("2.5"):
original_load = FxGraphCache.load
original_load_name = "torch._inductor.codecache.FxGraphCache.load"
def hijack_load(*args, **kwargs):
inductor_compiled_graph = original_load(*args, **kwargs)
nonlocal file_path
compiled_fn = inductor_compiled_graph.current_callable
file_path = compiled_fn.__code__.co_filename # noqa
if not file_path.startswith(self.cache_dir):
# hooked in the align_inputs_from_check_idxs function
# in torch/_inductor/utils.py
for cell in compiled_fn.__closure__:
if not callable(cell.cell_contents):
continue
if cell.cell_contents.__code__.co_filename.startswith(
self.cache_dir):
# this is the real file path compiled from Inductor
file_path = cell.cell_contents.__code__.co_filename
break
return inductor_compiled_graph
hijacked_compile_fx_inner = torch._inductor.compile_fx.compile_fx_inner # noqa
elif torch.__version__ >= "2.6":
# function renamed in 2.6
original_load_name = None
def hijacked_compile_fx_inner(*args, **kwargs):
output = torch._inductor.compile_fx.compile_fx_inner(
*args, **kwargs)
nonlocal hash_str
inductor_compiled_graph = output
if inductor_compiled_graph is not None:
nonlocal file_path
file_path = inductor_compiled_graph.current_callable.__code__.co_filename # noqa
hash_str = inductor_compiled_graph._fx_graph_cache_key
return output
def hijack_compiled_fx_graph_hash(*args, **kwargs):
out = compiled_fx_graph_hash(*args, **kwargs)
nonlocal hash_str
hash_str = out[0]
return out
def _check_can_cache(*args, **kwargs):
# no error means it can be cached.
# Inductor refuses to cache the graph outside of Dynamo
# tracing context, and also disables caching for graphs
# with high-order ops.
# For vLLM, in either case, we want to cache the graph.
# see https://github.com/pytorch/pytorch/blob/9f5ebf3fc609105a74eab4ccc24932d6353ff566/torch/_inductor/codecache.py#L1221 # noqa
return
def _get_shape_env() -> AlwaysHitShapeEnv:
return AlwaysHitShapeEnv()
with ExitStack() as stack:
# hijack to get the compiled graph itself
if original_load_name is not None:
stack.enter_context(patch(original_load_name, hijack_load))
# for hijacking the hash of the compiled graph
stack.enter_context(
patch("torch._inductor.codecache.compiled_fx_graph_hash",
hijack_compiled_fx_graph_hash))
# for providing a dummy shape environment
stack.enter_context(
patch("torch._inductor.codecache.FxGraphCache._get_shape_env",
_get_shape_env))
# for forcing the graph to be cached
stack.enter_context(
patch(
"torch._inductor.codecache.FxGraphCache._check_can_cache",
_check_can_cache))
compiled_graph = compile_fx(
graph,
example_inputs,
inner_compile=hijacked_compile_fx_inner,
config_patches=current_config)
assert hash_str is not None, (
"failed to get the hash of the compiled graph")
assert file_path is not None, (
"failed to get the file path of the compiled graph")
return compiled_graph, (hash_str, file_path)
def load(self,
handle: Any,
graph: fx.GraphModule,
example_inputs: List[Any],
graph_index: int,
runtime_shape: Optional[int] = None) -> Callable:
assert isinstance(handle, tuple)
assert isinstance(handle[0], str)
assert isinstance(handle[1], str)
hash_str = handle[0]
from torch._inductor.codecache import FxGraphCache
with patch("torch._inductor.codecache.FxGraphCache._get_shape_env",
lambda *args, **kwargs: AlwaysHitShapeEnv()):
if torch.__version__.startswith("2.5"):
inductor_compiled_graph = FxGraphCache._lookup_graph(
hash_str, example_inputs, True, False)
assert inductor_compiled_graph is not None, (
"Inductor cache lookup failed. Please remove"
f"the cache directory and try again." # noqa
)
elif torch.__version__ >= "2.6":
from torch._inductor.output_code import (
CompiledFxGraphConstantsWithGm)
constants = CompiledFxGraphConstantsWithGm(graph)
inductor_compiled_graph, _ = FxGraphCache._lookup_graph(
hash_str, example_inputs, True, None, constants)
assert inductor_compiled_graph is not None, (
"Inductor cache lookup failed. Please remove"
f"the cache directory and try again." # noqa
)
# Inductor calling convention (function signature):
# f(list) -> tuple
# Dynamo calling convention (function signature):
# f(*args) -> Any
# need to know if the graph returns a tuple
from torch._inductor.compile_fx import graph_returns_tuple
returns_tuple = graph_returns_tuple(graph)
# this is the callable we return to Dynamo to run
def compiled_graph(*args):
# convert args to list
list_args = list(args)
graph_output = inductor_compiled_graph(list_args)
# unpack the tuple if needed
if returns_tuple:
return graph_output
else:
return graph_output[0]
return compiled_graph
class EagerAdaptor(CompilerInterface):
name = "eager"
def compile(
self,
graph: fx.GraphModule,
example_inputs: List[Any],
compiler_config: Dict[str, Any],
runtime_shape: Optional[int] = None
) -> Tuple[Optional[Callable], Optional[Any]]:
# we don't need to compile the graph, just return the graph itself.
# It does not support caching, return None for the handle.
return graph, None