Files
pytorch/torch/_inductor/runtime/autotune_cache.py
James Wu bfe9e60ffb Simplify PrecompileContext to no longer be a CacheArtifactManager (#162886)
Summary:
This diff does a big refactor of PrecompileContext to make it considerably simpler: instead of being a CacheArtifactManager and managing a bunch of bytes, it simply stores two things: dynamo cache entries and backend cache entries. When asked, it stitches them together into PrecompileCacheEntries, which are stored by DynamoCache.

This structure then allows us to register DynamoCache to the regular Megacache API, instead of having two separate APIs that are confusing. It also lets us remove the autotune cache integration, since MegaCache API will automatically store autotune cache entries.

The intent here is that users who want to use caching precompile will simply be able to use torch.compiler.save_cache_artifacts as before, just with `torch.dynamo.config.caching_precompile` set to True. They can also directly interact with PrecompileContext if they wish to specifically only load Precompile entries, using PrecompileContext.create_cache_entries().

Saving single entries and such with DynamoCache still works normally.

Test Plan:
All existing unit tests pass.

Rollback Plan:

Differential Revision: D82380307

Pull Request resolved: https://github.com/pytorch/pytorch/pull/162886
Approved by: https://github.com/zhxchen17
2025-09-20 01:24:37 +00:00

642 lines
22 KiB
Python

"""
PyTorch Inductor Autotuning Cache System
This module implements a caching system for autotuning configurations in PyTorch's Inductor compiler.
It provides mechanisms to store and retrieve optimal kernel configurations both locally and remotely,
which significantly speeds up compilation by reusing previously discovered optimal parameters.
The caching system includes:
- Local filesystem caching for individual machine reuse
- Remote caching for sharing optimizations across machines
- Bundled caching to efficiently store multiple related configurations
- Cache invalidation based on PyTorch versions and backend changes
- Serialization/deserialization support for worker processes
Key components:
- AutotuneCache: Main class for managing cache access and storage
- AutotuneCacheBundler: Bundles multiple cache entries for efficient storage
- LocalAutotuneCache: Handles filesystem-based caching
- _LocalAutotuneCacheBackend: Low-level file operations for cache storage
- AutotuneCacheArtifact: Integration with PyTorch's artifact system
This caching system is critical for performance as it eliminates the need to re-run
expensive autotuning operations when the same kernels are compiled multiple times.
"""
from __future__ import annotations
import dataclasses
import hashlib
import logging
import os
import os.path
import re
from typing import Any, Optional, TYPE_CHECKING
from typing_extensions import override
import torch
from torch._inductor.runtime.runtime_utils import cache_dir
from torch.compiler._cache import (
CacheArtifact,
CacheArtifactFactory,
CacheArtifactManager,
)
from torch.utils._triton import has_triton
from ..remote_cache import (
create_cache,
JsonDataTy,
RemoteCache,
RemoteCacheBackend,
RemoteCacheJsonSerde,
)
from .triton_compat import Config, HAS_WARP_SPEC
if TYPE_CHECKING:
from ..remote_cache import Sample
log = logging.getLogger(__name__)
_InductorMetaTy = dict[str, object]
def inductor_meta_from_config() -> _InductorMetaTy:
from torch._inductor import config
backend_hash = None
if has_triton():
try:
backend_hash = torch.utils._triton.triton_hash_with_backend()
except RuntimeError:
# This can get the error:
# RuntimeError: 0 active drivers ([]). There should only be one.
pass
is_hip = None
if torch.version.hip is not None:
is_hip = True
return {
"autotune_local_cache": config.autotune_local_cache,
"autotune_remote_cache": config.autotune_remote_cache,
"backend_hash": backend_hash,
"bundled_autotune_remote_cache": config.bundled_autotune_remote_cache,
"coordinate_descent_tuning": config.coordinate_descent_tuning,
"is_fbcode": config.is_fbcode(),
"is_hip": is_hip,
}
@CacheArtifactFactory.register
class AutotuneCacheArtifact(CacheArtifact):
@override
def populate_cache(self) -> None:
autotune_cache = _LocalAutotuneCacheBackend()
key = os.path.join(cache_dir(), self.key)
autotune_cache._put(key, self.content)
@override
@staticmethod
def type() -> str:
return "autotune"
@override
@staticmethod
def encode(content: JsonDataTy) -> bytes:
assert not isinstance(content, bytes)
serde = RemoteCacheJsonSerde()
content_bytes = serde.encode(content)
assert isinstance(content_bytes, bytes)
return content_bytes
@dataclasses.dataclass
class AutotuneCache:
configs_hash: str
local_cache: Optional[tuple[RemoteCache[JsonDataTy], str]] = None
remote_cache: Optional[tuple[RemoteCache[JsonDataTy], str]] = None
# Create a AutotuneCache. Returns None if none of the caches can be used.
@staticmethod
def create(
inductor_meta: _InductorMetaTy, filename: str, configs_hash: str
) -> Optional[AutotuneCache]:
cache = AutotuneCache(configs_hash)
key = AutotuneCache._prepare_key(filename)
cache._setup_local_cache(inductor_meta, os.path.dirname(filename), key)
cache._setup_remote_autotune_cache(inductor_meta, key)
if cache.local_cache or cache.remote_cache:
return cache
else:
return None
@staticmethod
def _prepare_key(filename: str) -> str:
from torch.compiler import config as cconfig
# base of filename is already sha256 hash the source contents
key = f"{os.path.basename(filename)}:{cconfig.cache_key_tag}"
return hashlib.sha256(key.encode("utf-8")).hexdigest()
# Read the best config options from the most local cache and return it.
def _read(self) -> Optional[dict[str, JsonDataTy]]:
if local_cache := self.local_cache:
cache, key = local_cache
if best_config := cache.get(key):
if isinstance(best_config, dict):
return best_config
if remote_cache := self.remote_cache:
cache, key = remote_cache
if best_config := cache.get(key):
if isinstance(best_config, dict):
return best_config
return None
# Read the best config options from the most local cache and figure out
# which `configs` represents that option.
def read_best(
self, inductor_meta: _InductorMetaTy, configs: list[Config]
) -> Optional[Config]:
if best := self._read():
return _load_cached_autotuning(
best, self.configs_hash, configs, inductor_meta
)
return None
# Set up local filesystem caching information
def _setup_local_cache(
self, inductor_meta: _InductorMetaTy, dirname: str, cache_key: str
) -> None:
if not inductor_meta.get("autotune_local_cache", True):
return
from ..codecache import torch_key
"""
[Note: torch_key in autotune cache key]
Include torch_key() in the cache key so that different versions
of torch result in cache invalidation. This is important in case
of changes to the best_config format or other code changes that
are not backward compatible w.r.t. the cache.
"""
hasher = hashlib.sha256()
hasher.update(cache_key.encode("utf-8"))
hasher.update(torch_key())
updated_cache_key = hasher.hexdigest()
cache_filename = f"{dirname}/{updated_cache_key}.best_config"
local_cache = LocalAutotuneCache()
self.local_cache = (local_cache, cache_filename)
# Set up remote caching information
def _setup_remote_autotune_cache(
self, inductor_meta: _InductorMetaTy, cache_key: str
) -> None:
if not _should_use_remote_autotune_cache(inductor_meta):
return
if (backend_hash := inductor_meta.get("backend_hash", None)) is None:
log.debug(
"backend_hash is not passed on the inductor_meta, unable to use autotune remote cache"
)
return
assert isinstance(backend_hash, str)
from ..codecache import torch_key
is_fbcode = bool(inductor_meta.get("is_fbcode", False))
salt = "autotune-best-config-v2"
# re: torch_key - see [Note: torch_key in autotune cache key]
key = torch_key().hex() + backend_hash + self.configs_hash + salt
key = hashlib.sha256(key.encode("utf-8")).hexdigest()
remote_cache = create_cache(
key,
is_fbcode,
"FbRemoteAutotuneCache",
"RemoteAutotuneCache",
)
if not remote_cache:
return
# Save the args passed to create_cache
# in case AutotuneCache needs to be pickled
self.remote_cache_full_key = key
self.is_fbcode = is_fbcode
self.remote_cache = (remote_cache, cache_key)
# The AutotuneCache may be serialized/deserialized if we're using
# AsyncCompile worker processes to run triton compilation.
# This is because AutotuneCache instances are created on the worker
# process, but we need to run AutotuneCache.save on the parent process
# when actually doing autotuning.
def __getstate__(self) -> dict[str, Any]:
# The remote cache handles themselves may not be serializable
# So clear it and reconstruct it on setstate
remote_cache = getattr(self, "remote_cache", None)
return {
**self.__dict__,
# Save the cache_key portion
"remote_cache": remote_cache and remote_cache[1],
}
def __setstate__(self, state: dict[str, Any]) -> None:
# Reconstruct the remote cache on the parent class
self.__dict__.update(state)
if self.remote_cache is not None:
assert isinstance(self.remote_cache, str)
assert hasattr(self, "remote_cache_full_key")
assert hasattr(self, "is_fbcode")
cache_key = self.remote_cache
remote_cache = create_cache(
self.remote_cache_full_key,
self.is_fbcode,
"FbRemoteAutotuneCache",
"RemoteAutotuneCache",
)
if remote_cache is not None:
self.remote_cache = (remote_cache, cache_key)
else:
log.warning("Warning, failed to recreate remote cache after pickling")
self.remote_cache = None
# Save the config in the caches
def save(
self,
config: Config,
time_taken_ns: int,
found_by_coordesc: bool = False,
triton_cache_hash: Optional[str] = None,
) -> None:
data = {
**config.kwargs,
"num_warps": config.num_warps,
"num_stages": config.num_stages,
"configs_hash": self.configs_hash,
"found_by_coordesc": found_by_coordesc,
"time_taken_ms": time_taken_ns // 1000000, # Convert from NS to MS
"triton_cache_hash": triton_cache_hash,
}
if HAS_WARP_SPEC:
data.update(
{
"num_consumer_groups": getattr(config, "num_consumer_groups", 0),
"num_buffers_warp_spec": getattr(
config, "num_buffers_warp_spec", 0
),
}
)
if local_cache := self.local_cache:
cache, key = local_cache
cache.put(key, data)
AutotuneCacheBundler.put(key, data)
autotune_artifact_key = os.path.join(*key.split(os.sep)[-2:])
CacheArtifactManager.record_artifact(
AutotuneCacheArtifact.type(), autotune_artifact_key, data
)
if log.isEnabledFor(logging.DEBUG):
type_str = "coordesc" if found_by_coordesc else "heuristic"
log.debug("Save %s tuning result to %s", type_str, key)
if remote_cache := self.remote_cache:
cache, key = remote_cache
cache.put(key, data)
class _AutotuneCacheBundlerImpl:
"""
Caches a set of LocalAutotuneCacheBackend entries together in a single
cache.
"""
_key: str
_cache: RemoteCache[JsonDataTy]
# All known entries from LocalAutotuneCache.put()
_entries: dict[str, JsonDataTy]
def end_compile(self) -> None:
# TODO: Do we need to compute time_taken_ms and encode that somehow?
if self._entries:
self._cache.put(self._key, self._entries)
def put(self, basename: str, data: JsonDataTy) -> None:
# Do we need to worry about duplicates? We only have a single local fs
# entry - so probably not.
self._entries[basename] = data
def __init__(self, key: str, cache: RemoteCache[JsonDataTy]) -> None:
self._key = key
self._cache = cache
self._entries = {}
def sync(self) -> None:
# We don't currently use this - but we could async load starting at
# `begin_compile` and wait for the load to be finished here.
pass
@classmethod
def _should_use_bundled_autotune_remote_cache(
cls, inductor_meta: _InductorMetaTy
) -> bool:
# The bundled autotune cache is only available if you've also got local
# caching enabled (because we feed the bundled data to the local cache).
if not inductor_meta.get("autotune_local_cache", True):
return False
# Check if the we're enabled via config
if (
bundled_autotune_remote_cache := inductor_meta.get(
"bundled_autotune_remote_cache"
)
) is not None:
return bool(bundled_autotune_remote_cache)
if not cls._get_is_fbcode(inductor_meta):
return False
if torch._utils_internal.is_fb_unit_test():
return False
if inductor_meta.get("is_hip"):
return False
try:
from torch._inductor.fb.remote_cache import REMOTE_CACHE_VERSION
except ModuleNotFoundError:
return False
jk = torch._utils_internal.justknobs_getval_int(
"pytorch/remote_cache:bundled_autotune_remote_cache_version"
)
return REMOTE_CACHE_VERSION >= jk
def _load_cache(self) -> bool:
from torch._inductor import codecache
# The single key is defined on construction of the cache.
entries = self._cache.get(self._key)
if entries is None or not isinstance(entries, dict):
# We couldn't load the cache - so mark _entries as non-None so we
# store local cache values.
return False
# Go through the entries we got from the cache and save them locally.
time_saved_ns = 0
for basename, data in entries.items():
# Reconstruct the final filename (see put())
root, ext = _splitext_nodot(basename)
_, _, filename = codecache.get_path(root, ext)
if isinstance(data, dict) and (tsns := data.get("time_saved_ns")):
time_saved_ns += int(tsns) # type: ignore[arg-type]
local_cache = LocalAutotuneCache()
local_cache.put(filename, data)
codecache.add_ephemeral_timeout_increase_for_distributed(time_saved_ns)
return True
@staticmethod
def _get_is_fbcode(inductor_meta: _InductorMetaTy) -> bool:
return bool(inductor_meta.get("is_fbcode", False))
@staticmethod
def _get_backend_hash(inductor_meta: _InductorMetaTy) -> str:
backend_hash = inductor_meta["backend_hash"]
assert isinstance(backend_hash, str)
return backend_hash
class AutotuneCacheBundler:
_bundler: Optional[_AutotuneCacheBundlerImpl] = None
def __init__(self) -> None:
pass
# Call this before we start any autotune computation for an inductor python
# file. On a cache hit it copies the individual results into the local
# autotune caches.
@classmethod
def begin_compile(
cls,
inductor_meta: _InductorMetaTy,
*,
code: Optional[str] = None,
code_hash: Optional[str] = None,
) -> None:
assert cls._bundler is None
if code is not None:
assert code_hash is None, "Cannot specify both code and code_hash"
code_hash = _comment_stripped_hash(code)
assert code_hash is not None
if not _AutotuneCacheBundlerImpl._should_use_bundled_autotune_remote_cache(
inductor_meta
):
return
cache = create_cache(
"bundled-autotune-v1",
_AutotuneCacheBundlerImpl._get_is_fbcode(inductor_meta),
"FbRemoteBundledAutotuneCache",
"RemoteBundledAutotuneCache",
)
if not cache:
return
# We're starting a compilation phase. We have a cache key for the code
# we're compiling. We'll get the individual autotune bundles later (via
# self.put()). For now create the AutotuneCacheBundler and try to load
# from the cache.
salt = "bundled-autotune-best-configs-v1"
backend_hash = _AutotuneCacheBundlerImpl._get_backend_hash(inductor_meta)
# TODO: The autotune cache includes configs_hash in the key. The problem
# is that the configs_hash includes info from the individual pointwise()
# calls (size_hints, for example) which we can't know yet. I *think*
# that info is basically present in the `code_hash` (since it's a
# parameter to the pointwise decorator) - but is there other info we
# need to include from inductor_meta?
key = code_hash + backend_hash + salt
key = hashlib.sha256(key.encode("utf-8")).hexdigest()
bundler = _AutotuneCacheBundlerImpl(key, cache)
if not bundler._load_cache():
# We couldn't load from the cache - so save the data so we can store
# the saved autotunes.
cls._bundler = bundler
# If we get a cache hit don't bother saving any of the individual
# autotune results.
# Call this after all individual autotune results are finished for a
# inductor python file. If we gathered any individual results then we bundle
# those and put it into the cache.
@classmethod
def end_compile(cls) -> None:
if bundler := cls._bundler:
cls._bundler = None
bundler.end_compile()
@classmethod
def sync(cls) -> None:
if bundler := cls._bundler:
bundler.sync()
@classmethod
def put(cls, filename: str, data: JsonDataTy) -> None:
if bundler := cls._bundler:
# The filename comes in as something like
# "/tmp/tmp{random}/{aa}/{basename}.py" (where aa is
# basename[1:3]). Strip it down and make sure that it looks like a path
# we could reconstruct (because it's possible for the caller to
# customize the path).
basename = os.path.basename(filename)
# TODO: check cache_dir() vs filename, then strip dirname
bundler.put(basename, data)
# Remove the comments from the code (which include things like run ids and file
# paths) and then hash the result.
def _comment_stripped_hash(code: str) -> str:
code = re.sub(r"#.*$", "", code, count=0, flags=re.MULTILINE)
return torch._inductor.codecache.code_hash(code)
def _should_use_remote_autotune_cache(inductor_meta: _InductorMetaTy) -> bool:
if (config := inductor_meta.get("autotune_remote_cache")) is not None:
return bool(config)
if not inductor_meta.get("is_fbcode"):
return False
if torch._utils_internal.is_fb_unit_test():
return False
if inductor_meta.get("is_hip"):
return False
try:
from torch._inductor.fb.remote_cache import REMOTE_CACHE_VERSION
except ModuleNotFoundError:
return False
return REMOTE_CACHE_VERSION >= torch._utils_internal.justknobs_getval_int(
"pytorch/remote_cache:autotune_memcache_version"
)
def _load_cached_autotuning(
best_config: dict[str, JsonDataTy],
configs_hash: str,
configs: list[Config],
inductor_meta: _InductorMetaTy,
) -> Optional[Config]:
if best_config is None:
return None
if best_config.pop("configs_hash", None) != configs_hash:
return None
# Remove time taken for comparison
best_config.pop("time_taken_ms", None)
best_config.pop("triton_cache_hash", None)
if inductor_meta.get("coordinate_descent_tuning") and best_config.pop(
"found_by_coordesc", False
):
num_warps = best_config.pop("num_warps")
num_stages = best_config.pop("num_stages")
# Extract common arguments
config_args = {
"num_warps": num_warps,
"num_stages": num_stages,
}
if HAS_WARP_SPEC:
config_args.update(
{
"num_consumer_groups": best_config.pop("num_consumer_groups", 0),
"num_buffers_warp_spec": best_config.pop(
"num_buffers_warp_spec", 0
),
}
)
# Create the triton_config with the appropriate arguments
triton_config = Config(best_config, **config_args)
triton_config.found_by_coordesc = True
return triton_config
matching_configs = [
cfg
for cfg in configs
if all(val == best_config.get(key) for key, val in cfg.kwargs.items())
and cfg.num_warps == best_config.get("num_warps")
and cfg.num_stages == best_config.get("num_stages")
]
if len(matching_configs) != 1:
return None
return matching_configs[0]
class _LocalAutotuneCacheBackend(RemoteCacheBackend[bytes]):
@override
def _get(self, key: str) -> Optional[bytes]:
try:
with open(key, "rb") as fd:
return fd.read()
except FileNotFoundError:
return None
@override
def _put(self, key: str, data: bytes) -> None:
os.makedirs(os.path.dirname(key), exist_ok=True)
from torch._inductor import codecache
codecache.write_atomic(key, data)
class LocalAutotuneCache(RemoteCache[JsonDataTy]):
def __init__(self) -> None:
backend = _LocalAutotuneCacheBackend()
serde = RemoteCacheJsonSerde()
super().__init__(backend, serde)
@override
def _get(self, key: str, sample: Optional[Sample]) -> Optional[JsonDataTy]:
AutotuneCacheBundler.sync()
result = super()._get(key, sample)
if result is not None:
assert isinstance(result, dict)
# What? Why are we doing a put() here? Imagine we have a new model
# that reuses some existing kernels that have already been
# compiled. If we didn't do a `put` here (on cache hit) then the new
# model would only bundle *newly* compiled kernels, not existing
# kernels that were already compiled and cached.
AutotuneCacheBundler.put(key, result)
autotune_artifact_key = os.path.join(*key.split(os.sep)[-2:])
CacheArtifactManager.record_artifact(
AutotuneCacheArtifact.type(), autotune_artifact_key, result
)
return result
@override
def _put(self, key: str, value: JsonDataTy, sample: Optional[Sample]) -> None:
AutotuneCacheBundler.put(key, value)
super()._put(key, value, sample)
def _splitext_nodot(basename: str) -> tuple[str, str]:
root, ext = os.path.splitext(basename)
if ext:
ext = ext[1:]
return root, ext