72 lines
2.7 KiB
Python
72 lines
2.7 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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"""Drop FA4's JIT kernel caches when its FA4_*/FA_* tuning environment changes.
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FA4 reads these knobs while tracing a kernel but does not include them in its compile-cache key.
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"""
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from __future__ import annotations
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from collections.abc import Iterable, Mapping
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import fastvideo.envs as envs
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from fastvideo.logger import init_logger
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logger = init_logger(__name__)
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FA4_ENV_PREFIXES = ("FA4_", "FA_")
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_JIT_CACHE_ATTRS = ("compile_cache", "compile_cache_pre", "compile_cache_post")
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_last_fingerprint: tuple[tuple[str, str], ...] | None = None
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def fa4_env_fingerprint(environ: Mapping[str, str] | None = None, ) -> tuple[tuple[str, str], ...]:
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"""Return the sorted ``(name, value)`` pairs of FA4 tuning env vars."""
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source = envs.external_with_prefixes("FA4_", "FA_") if environ is None else environ
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pairs = [(name, source[name]) for name in source if name.startswith(FA4_ENV_PREFIXES)]
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pairs.sort()
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return tuple(pairs)
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def clear_fa4_jit_caches(kernel_objects: Iterable[object]) -> int:
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"""Drop every FA4 JIT cache on ``kernel_objects``; return entries dropped."""
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cleared = 0
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for kernel_object in kernel_objects:
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for attribute in _JIT_CACHE_ATTRS:
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cache = getattr(kernel_object, attribute, None)
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if isinstance(cache, dict) and cache:
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cleared += len(cache)
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cache.clear()
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return cleared
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def reset_fa4_env_fingerprint() -> None:
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"""Forget the last observed fingerprint (tests / fresh-process semantics)."""
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global _last_fingerprint
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_last_fingerprint = None
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def invalidate_fa4_jit_caches_on_env_change(
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kernel_objects: Iterable[object],
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environ: Mapping[str, str] | None = None,
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) -> bool:
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"""Clear FA4's JIT caches if the FA4 tuning env changed since the last call (always on the first call)."""
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global _last_fingerprint
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fingerprint = fa4_env_fingerprint(environ)
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if fingerprint == _last_fingerprint:
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return False
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previous, _last_fingerprint = _last_fingerprint, fingerprint
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cleared = clear_fa4_jit_caches(kernel_objects)
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if previous is not None:
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changed = sorted(name for name in {k
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for k, _ in previous} | {k
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for k, _ in fingerprint}
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if dict(previous).get(name) != dict(fingerprint).get(name))
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if cleared:
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logger.info(
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"FA4 tuning env changed (%s); dropped %d cached JIT kernel(s) "
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"so the new setting is not served stale code", ", ".join(changed), cleared)
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else:
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logger.debug("FA4 tuning env changed (%s); FA4 JIT cache was empty", ", ".join(changed))
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return True
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