perf(image): compile numeric parity, cache-hook compile arming, FBCache toggle crash fix, TE fp8 zero-row guard

Applies the video round-2 accuracy findings to the image diffusion stack and fixes
two real image-path bugs found while measuring. All numbers B200, production
settings (family default steps/guidance, 1024px, seed 42, 4 fixed prompts), LPIPS
(AlexNet) via the new scripts/image_speedmem_bench.py, which drives the production
lever functions in the loader's own order.

- inductor precision parity: emulate_precision_casts=True on the regional-compile
  path (fused pointwise kernels keep fp32 intermediates where eager rounds to bf16
  between ops). Pairwise LPIPS of the compiled tier vs the same-stack eager tier:
  Qwen-Image 0.019 to 0.006 at identical speed (72.4 vs 72.5 ms/step), FLUX.1-dev
  0.046 to 0.029 at +2% step time (69.8 vs 68.3, reproduced), FLUX.2-klein-4B
  0.018 to 0.017 at identical speed. Snapshot/restored with the other process-wide
  backend flags so an off load never inherits it.
- cache x compile composition: re-point each cache hook's fn_ref.original_forward
  at a torch.compile'd wrapper of the same bound method (armed only where the
  speed layer compiled the block; restored before every disable_cache and before
  the partial-hook cleanup). Qwen-Image FBCache computed steps 91.8 to 71.2 ms
  (back at the uncached compiled rate), 1.21x end to end (7.36 to 6.06 s per 4
  images); FLUX.1-dev already traced through its FBCache hook and is measured
  neutral (same-process armed vs unarmed latents bit-identical). Skip counts
  within noise (13 vs 11 of 76; pairwise LPIPS 0.005).
- FBCache mid-session toggle crash: diffusers 0.39 caches the HookRegistry child
  list on first cache_context use, so an uncached generation followed by a
  20+-step generation (the auto toggle path) enabled hooks the context never
  reached and crashed with "No context is set" (reproduced live on FLUX.1-dev).
  Invalidate the stale child cache after every enable_cache.
- TE fp8_dynamic zero-row guard: torchao per-row fp8 derives a per-output-channel
  scale from the row amax, so an all-zero weight row is 0/0 = NaN. SDXL's
  text_encoder_2 (OpenCLIP bigG) ships exactly such a row, and every explicit
  fp8_dynamic SDXL render came out black; keep zero-row Linears dense (LPIPS
  0.976 black to 0.096 working). Other families' encoders have no such rows and
  are byte-identical.
- No AUTO TE quant exists on the image branch (text_encoder_quant defaults dense,
  explicit-only), so the video round's auto-dense retune has no image analogue;
  the explicit lever's cost is now measured (TE fp8_dynamic alone, LPIPS vs
  bit-exact: Qwen-Image 0.038, FLUX.1-dev 0.084, SDXL 0.096; no speed win, VRAM
  -6.5 GB on Qwen-Image) for the docs.

Tests: 96 passing across the cache/speed/precision suites (11 new arming, 2
child-registry, 2 zero-row, 4 inductor-flag); ruff clean.
This commit is contained in:
Daniel Han 2026-07-10 16:07:46 +00:00
commit de2f22df2b
7 changed files with 997 additions and 2 deletions

View file

@ -64,6 +64,126 @@ def normalize_transformer_cache(value: Optional[str]) -> Optional[str]:
return normalized
def _invalidate_child_registry_cache(transformer: Any) -> None:
"""Drop the HookRegistry's cached child-registry list after (un)installing hooks.
``cache_context`` propagates the state context through ``_get_child_registries``,
which diffusers 0.39 caches on first use. An UNCACHED generation already calls
``cache_context`` (the pipeline wraps every denoise call), creating the
transformer-level registry with an EMPTY cached child list -- so a later
``enable_cache`` (the auto step-count toggle engaging FBCache mid-session) installs
block hooks that ``_set_context`` never reaches, and the first cached forward dies
with "No context is set". Invalidate the stale cache so the next ``cache_context``
rebuilds it over the freshly hooked blocks. Best-effort and cheap (one attribute)."""
registry = getattr(transformer, "_diffusers_hook", None)
if registry is not None and getattr(registry, "_child_registries_cache", None) is not None:
try:
registry._child_registries_cache = None
except Exception: # noqa: BLE001 -- diffusers internals moved; leave as-is
pass
# diffusers' cache hook registry names whose compute branch we re-point at a compiled
# inner forward (leader = the measuring first block, block = the remaining ones); both
# hook families share the fn_ref layout.
_CACHE_HOOK_NAMES = (
"mag_cache_leader_block_hook",
"mag_cache_block_hook",
"fbc_leader_block_hook",
"fbc_block_hook",
)
def _compile_hooked_block_inners(transformer: Any, logger: Any = None) -> int:
"""Restore the regional compile on cache-hooked blocks' COMPUTED steps.
``enable_cache`` replaces each block's ``forward`` with the hook's ``new_forward``
(stashing the pre-hook bound method in ``fn_ref.original_forward``), whose skip
decision is data-dependent Python: MagCache ``@torch.compiler.disable``s the whole
``new_forward`` (recursive -- the compute branch runs EAGER), and even FBCache's
traceable ``new_forward`` graph-breaks around its disabled threshold decision,
which on some archs (measured: Qwen-Image) drops the compute branch's call into
``original_forward`` out of the compiled region -- the block's regional compile
artifact (``_compiled_call_impl``) is never reached and the cache forfeits the
compile win on every non-skipped step. An explicitly ``torch.compile``d callable
re-enables
dynamo for its own extent even inside a disabled frame, so re-pointing
``fn_ref.original_forward`` at a compiled wrapper of the same bound method restores
compiled compute steps while the skip decision stays eager exactly as designed.
Measured (B200, scripts/image_speedmem_bench.py): Qwen-Image FBCache computed steps
91.8 -> 71.2 ms (= the uncached compiled rate), 1.21x end to end; FLUX.1-dev is
neutral (its FBCache ``new_forward`` happens to trace, so computed steps were
already compiled -- same-process armed vs unarmed latents bit-identical); on the
video DiT balanced MagCache went 39.4 -> 26.9 s at 50 steps.
Only blocks the speed layer actually compiled are armed (``_compiled_call_impl``
guard -- eager tiers stay untouched), and only when ``original_forward`` is a plain
bound method (a stacked hook chain, e.g. offload, captures a partial and is
skipped). Idempotent via the ``_unsloth_orig_inner`` marker; best-effort. Returns
the number of hooks armed."""
try:
import torch
except Exception: # noqa: BLE001 -- no torch, nothing to arm
return 0
armed = 0
try:
for module in transformer.modules():
registry = getattr(module, "_diffusers_hook", None)
if registry is None or getattr(module, "_compiled_call_impl", None) is None:
continue
hooks = getattr(registry, "hooks", None) or {}
for name in _CACHE_HOOK_NAMES:
hook = hooks.get(name)
fn_ref = getattr(hook, "fn_ref", None) if hook is not None else None
orig = getattr(fn_ref, "original_forward", None)
if orig is None or getattr(hook, "_unsloth_orig_inner", None) is not None:
continue
if getattr(orig, "__self__", None) is None:
continue # not the plain bound method; arming would miss the block
# fullgraph=False / dynamic=True: a cache is active by definition (its
# decision points graph-break) and this matches the default tier the
# regional compile used. Dynamo caches per code object, so re-arming
# after a toggle is effectively free (~0.03 s).
fn_ref.original_forward = torch.compile(orig, fullgraph = False, dynamic = True)
hook._unsloth_orig_inner = orig
armed += 1
except Exception as exc: # noqa: BLE001 -- best-effort: the cache still works eager
_warn(logger, "cache-hook inner compile", exc)
return armed
if armed and logger is not None:
logger.info(
"diffusion.cache: %d cache-hooked block(s) armed with compiled inner forwards",
armed,
)
return armed
def _restore_hooked_block_inners(transformer: Any) -> None:
"""Undo ``_compile_hooked_block_inners``: put the plain bound methods back and clear
the markers. MUST run before ``disable_cache`` -- ``remove_hook`` splices
``fn_ref.original_forward`` back into ``module.forward``, and leaving the compiled
wrapper there would pin a stale compiled callable onto the uncached path."""
try:
modules = list(transformer.modules())
except Exception: # noqa: BLE001 -- not a torch module (tests/fakes): nothing armed
return
for module in modules:
registry = getattr(module, "_diffusers_hook", None)
if registry is None:
continue
hooks = getattr(registry, "hooks", None) or {}
for name in _CACHE_HOOK_NAMES:
hook = hooks.get(name)
orig = getattr(hook, "_unsloth_orig_inner", None) if hook is not None else None
if orig is None:
continue
try:
hook.fn_ref.original_forward = orig
hook._unsloth_orig_inner = None
except Exception: # noqa: BLE001 -- per-hook best-effort
pass
def _pipeline_opens_cache_context(pipe: Any) -> bool:
"""Whether the pipeline enters ``transformer.cache_context(...)`` in its denoise loop.
The First-Block-Cache hook requires it at run time, and a CacheMixin transformer alone
@ -137,6 +257,15 @@ def apply_step_cache(
config = FirstBlockCacheConfig(threshold = thr)
enable_cache(config)
# enable_cache AFTER the pipe has already run leaves a stale cached child-registry
# list on the transformer's HookRegistry; the block hooks just installed would then
# never receive the cache context. Must follow every enable_cache.
_invalidate_child_registry_cache(transformer)
# If the blocks are already regionally compiled (the generation-time toggle
# path: compile ran at load), re-point the fresh hooks' compute branch at
# compiled inners; the load path (cache before compile) is armed by
# _compile_repeated_blocks instead. No-op when nothing is compiled.
_compile_hooked_block_inners(transformer, logger)
try:
transformer._unsloth_step_cache = f"{mode}@{thr}"
except Exception: # noqa: BLE001 — marker is best-effort
@ -146,7 +275,10 @@ def apply_step_cache(
return mode
except Exception as exc: # noqa: BLE001 — incompatible model -> run uncached
# enable_cache can fail after hooking some blocks; drop any partial hooks so
# the reported-uncached model doesn't actually run half-cached.
# the reported-uncached model doesn't actually run half-cached. Any armed
# compiled inners must be restored FIRST (remove_hook splices original_forward
# back into module.forward).
_restore_hooked_block_inners(transformer)
try:
transformer.disable_cache()
except Exception: # noqa: BLE001
@ -225,6 +357,10 @@ def maybe_toggle_step_cache(
disable_cache = getattr(transformer, "disable_cache", None)
if callable(disable_cache):
try:
# Before remove_hook splices fn_ref.original_forward back into
# module.forward: the compiled inner wrappers must not leak onto the
# uncached path.
_restore_hooked_block_inners(transformer)
disable_cache()
transformer._unsloth_step_cache = None
if logger is not None:

View file

@ -217,6 +217,24 @@ def _cast_int8_selective(encoder: Any, target: Any, skip_first: int, skip_last:
quantize_(encoder, _make_quant_config(TQ_INT8), filter_fn = filter_fn)
def _weight_has_zero_output_row(module: Any) -> bool:
"""True when a Linear's weight contains an all-zero OUTPUT row. torchao's per-row
fp8 scheme derives a per-output-channel scale from that row's amax, so a dead row
yields scale 0 -> 0/0 = NaN through the whole forward. Real checkpoints ship such
rows: SDXL's text_encoder_2 (OpenCLIP ViT-bigG) has one in
``text_model.encoder.layers.2.self_attn.out_proj`` -- measured on B200: every
fp8_dynamic SDXL render came out black (NaN embeddings) until this Linear is left
dense. Cheap (one amax per Linear, once per load); False on any error so the
caster's own failure handling stays in charge."""
try:
weight = getattr(module, "weight", None)
if weight is None or weight.ndim != 2:
return False
return bool((weight.abs().amax(dim = -1) == 0).any().item())
except Exception: # noqa: BLE001 -- unreadable weight: let quantize_ decide
return False
def _cast_fp8_dynamic(encoder: Any, target: Any) -> None:
# torchao dynamic fp8 COMPUTE, per-row (per-token activation + per-output-channel weight ->
# torch._scaled_mm on the fp8 tensor cores). Unlike the layerwise `fp8` backend this keeps the
@ -232,9 +250,15 @@ def _cast_fp8_dynamic(encoder: Any, target: Any) -> None:
# require_bf16: scaled_mm asserts a bf16 weight, so skip any stray non-bf16 Linear the encoder
# keeps (belt-and-suspenders over the named T5 wo exclusion) rather than aborting the pass.
filter_fn = make_filter_fn(
base = make_filter_fn(
DEFAULT_MIN_LINEAR_FEATURES, _te_exclude_tokens(encoder), require_bf16 = True
)
# A Linear with an all-zero output row NaNs under per-row scaling (scale 0 -> 0/0);
# keep exactly those Linears dense so one dead row cannot black out every render.
def filter_fn(module: Any, fqn: str = "") -> bool:
return base(module, fqn) and not _weight_has_zero_output_row(module)
quantize_(encoder, _make_quant_config(TQ_FP8), filter_fn = filter_fn)

View file

@ -77,6 +77,9 @@ def snapshot_backend_flags() -> Optional[dict]:
state["cudnn_tf32"] = bool(cudnn.allow_tf32)
if hasattr(cudnn, "benchmark"):
state["cudnn_benchmark"] = bool(cudnn.benchmark)
inductor_cfg = _inductor_config()
if inductor_cfg is not None and hasattr(inductor_cfg, "emulate_precision_casts"):
state["inductor_emulate_precision_casts"] = bool(inductor_cfg.emulate_precision_casts)
return state
@ -103,6 +106,19 @@ def restore_backend_flags(state: Optional[dict]) -> None:
cudnn = getattr(torch.backends, "cudnn", None)
_set(cudnn, "allow_tf32", "cudnn_tf32")
_set(cudnn, "benchmark", "cudnn_benchmark")
_set(_inductor_config(), "emulate_precision_casts", "inductor_emulate_precision_casts")
def _inductor_config() -> Any:
"""``torch._inductor.config`` or None. Resolved as attributes off the imported torch
module (real torch exposes ``_inductor`` directly after ``import torch``) rather
than a submodule import, so a stubbed/partial torch (tests, exotic builds) cleanly
reports None instead of picking a stale real module out of ``sys.modules``."""
try:
import torch
return getattr(getattr(torch, "_inductor", None), "config", None)
except Exception: # noqa: BLE001 — no inductor -> nothing to snapshot/set
return None
def normalize_speed_mode(value: Optional[str]) -> str:
@ -342,6 +358,19 @@ def _compile_repeated_blocks(
for _limit_attr in ("recompile_limit", "cache_size_limit"): # name varies by torch ver
if hasattr(dynamo_cfg, _limit_attr):
setattr(dynamo_cfg, _limit_attr, max(getattr(dynamo_cfg, _limit_attr) or 0, 64))
# Match eager's intermediate rounding inside inductor's fused pointwise kernels:
# by default they keep chains in fp32 where eager materialises bf16 between ops,
# a per-forward rounding delta that a multi-step denoise amplifies chaotically.
# Measured (B200, scripts/image_speedmem_bench.py, pairwise LPIPS of the
# compiled tier vs the same-stack eager tier): Qwen-Image 0.019 -> 0.006 at
# identical speed, FLUX.1-dev 0.046 -> 0.029 at +2% step time, FLUX.2-klein
# 0.018 -> 0.017 at identical speed; on the video DiT (HunyuanVideo-1.5-720p)
# full-clip LPIPS vs bit-exact drops 0.221 -> 0.052 at zero cost. Process-
# global, so snapshot_backend_flags carries it and unload restores the prior
# value.
inductor_cfg = _inductor_config()
if inductor_cfg is not None and hasattr(inductor_cfg, "emulate_precision_casts"):
inductor_cfg.emulate_precision_casts = True
except Exception as exc: # noqa: BLE001 — optimisation only
_warn(logger, "compile_repeated_blocks", exc)
return False
@ -354,6 +383,20 @@ def _compile_repeated_blocks(
engaged = True
except Exception as exc: # noqa: BLE001 — optimisation only
_warn(logger, "compile_repeated_blocks", exc)
continue
# A step cache engaged BEFORE this compile (the production load order) has
# already wrapped each block's forward in a @torch.compiler.disable'd hook, so
# the compute branch would run eager on every non-skipped step and forfeit the
# regional compile entirely. Re-point the hooks' inner forward at compiled
# wrappers; no-op when no cache hooks are installed. The toggle path (cache
# engaged after load) is armed by apply_step_cache instead. Lazy import:
# diffusion_cache imports nothing from this module, but keep the dependency
# one-directional at import time.
try:
from .diffusion_cache import _compile_hooked_block_inners
_compile_hooked_block_inners(transformer, logger)
except Exception as exc: # noqa: BLE001 — optimisation only
_warn(logger, "cache-hook inner compile", exc)
return engaged

View file

@ -356,3 +356,206 @@ def test_toggle_noop_without_cache_support(monkeypatch):
def test_toggle_noop_without_transformer():
assert maybe_toggle_step_cache(types.SimpleNamespace(), steps = 28) is None
# ── compiled cache-hook inners (regional compile x step cache composition) ──────────
import functools # noqa: E402
from core.inference.diffusion_cache import ( # noqa: E402
_compile_hooked_block_inners,
_invalidate_child_registry_cache,
_restore_hooked_block_inners,
)
class _BoundInner:
"""Provides a plain bound method for fn_ref.original_forward (__self__ present)."""
def forward(self, *args, **kwargs):
return "eager"
def _hooked_block(
*,
compiled = True,
hook_name = "fbc_block_hook",
bound = True,
):
inner = _BoundInner()
orig = inner.forward if bound else functools.partial(_BoundInner.forward, inner)
hook = types.SimpleNamespace(fn_ref = types.SimpleNamespace(original_forward = orig))
block = types.SimpleNamespace(
_diffusers_hook = types.SimpleNamespace(hooks = {hook_name: hook}),
_compiled_call_impl = object() if compiled else None,
)
return block, hook, orig
def _fake_dit(blocks):
return types.SimpleNamespace(modules = lambda: [types.SimpleNamespace()] + blocks)
def _stub_torch_compile(monkeypatch):
compiled_calls = []
def _compile(fn, **kwargs):
compiled_calls.append((fn, kwargs))
wrapper = lambda *a, **k: fn(*a, **k) # noqa: E731
wrapper._unsloth_test_compiled_of = fn
return wrapper
torch = types.ModuleType("torch")
torch.compile = _compile
monkeypatch.setitem(sys.modules, "torch", torch)
return compiled_calls
def test_arming_swaps_inner_for_compiled_wrapper(monkeypatch):
calls = _stub_torch_compile(monkeypatch)
block, hook, orig = _hooked_block()
assert _compile_hooked_block_inners(_fake_dit([block])) == 1
assert hook.fn_ref.original_forward is not orig
assert hook.fn_ref.original_forward._unsloth_test_compiled_of is orig
assert hook._unsloth_orig_inner is orig
# The inner compile must match the cache-active tier: graph-breakable + dynamic.
assert calls[0][1] == {"fullgraph": False, "dynamic": True}
def test_arming_is_idempotent(monkeypatch):
_stub_torch_compile(monkeypatch)
block, hook, _ = _hooked_block()
dit = _fake_dit([block])
assert _compile_hooked_block_inners(dit) == 1
once = hook.fn_ref.original_forward
assert _compile_hooked_block_inners(dit) == 0 # marker short-circuits
assert hook.fn_ref.original_forward is once
def test_arming_skips_uncompiled_blocks(monkeypatch):
# An eager-tier load has no _compiled_call_impl: the hook must stay untouched
# (compiling the inner would ADD compile where the user chose eager).
_stub_torch_compile(monkeypatch)
block, hook, orig = _hooked_block(compiled = False)
assert _compile_hooked_block_inners(_fake_dit([block])) == 0
assert hook.fn_ref.original_forward is orig
def test_arming_skips_partial_captured_inner(monkeypatch):
# A stacked hook chain (e.g. group offload) captures a functools.partial, not the
# plain bound method; arming would compile the wrong layer of the chain.
_stub_torch_compile(monkeypatch)
block, hook, orig = _hooked_block(bound = False)
assert _compile_hooked_block_inners(_fake_dit([block])) == 0
assert hook.fn_ref.original_forward is orig
def test_arming_covers_every_cache_hook_family(monkeypatch):
# FBCache is the image cache today, but the hook-name table already covers the
# MagCache layout too (same fn_ref shape), so a future mode arms for free.
_stub_torch_compile(monkeypatch)
names = (
"mag_cache_leader_block_hook",
"mag_cache_block_hook",
"fbc_leader_block_hook",
"fbc_block_hook",
)
blocks = [_hooked_block(hook_name = n)[0] for n in names]
assert _compile_hooked_block_inners(_fake_dit(blocks)) == len(names)
def test_restore_puts_the_exact_original_back(monkeypatch):
_stub_torch_compile(monkeypatch)
block, hook, orig = _hooked_block()
dit = _fake_dit([block])
_compile_hooked_block_inners(dit)
_restore_hooked_block_inners(dit)
assert hook.fn_ref.original_forward is orig
assert hook._unsloth_orig_inner is None
def test_restore_tolerates_fakes_without_modules():
_restore_hooked_block_inners(_MixinTransformer()) # no .modules(): no-op
def test_apply_step_cache_arms_compiled_blocks_on_toggle(monkeypatch):
# The generation-time toggle engages the cache AFTER the load already compiled the
# blocks; apply_step_cache must arm the fresh hooks itself.
_stub_diffusers(monkeypatch)
_stub_torch_compile(monkeypatch)
block, hook, orig = _hooked_block()
class _T(_MixinTransformer):
def modules(self):
return [block]
t = _T()
engaged = apply_step_cache(_pipe(t), mode = "fbcache")
assert engaged == TC_FBCACHE
assert hook.fn_ref.original_forward is not orig
assert hook._unsloth_orig_inner is orig
def test_toggle_disable_restores_inners_before_disable(monkeypatch):
# remove_hook splices fn_ref.original_forward back into module.forward, so the
# compiled wrapper must be swapped out BEFORE disable_cache runs.
_stub_diffusers(monkeypatch)
order = []
class _T(_ToggleTransformer):
def disable_cache(self):
super().disable_cache()
order.append("disable")
def modules(self):
order.append("restore-walk")
return []
t = _T()
maybe_toggle_step_cache(_pipe(t), steps = 28)
mode = maybe_toggle_step_cache(_pipe(t), steps = 8)
assert mode is None and t.disables == 1
assert order[-2:] == ["restore-walk", "disable"]
def test_enable_failure_restores_inners_before_partial_disable(monkeypatch):
# enable_cache can fail after hooking (and arming) some blocks; the partial-hook
# cleanup must un-arm them before disable_cache splices original_forward back.
_stub_diffusers(monkeypatch)
order = []
class _T(_ToggleTransformer):
def enable_cache(self, config):
raise RuntimeError("block signature not recognised")
def disable_cache(self):
super().disable_cache()
order.append("disable")
def modules(self):
order.append("restore-walk")
return []
t = _T()
assert apply_step_cache(_pipe(t), mode = "fbcache") is None
assert order == ["restore-walk", "disable"]
# ── stale child-registry cache invalidation (mid-session enable) ────────────────────
def test_enable_invalidates_stale_child_registry_cache(monkeypatch):
# diffusers 0.39 caches the child-registry list on first cache_context use; an
# UNCACHED generation already populates it (empty), so a later toggle-time
# enable_cache would install hooks the context never reaches ("No context is set").
_stub_diffusers(monkeypatch)
t = _MixinTransformer()
t._diffusers_hook = types.SimpleNamespace(_child_registries_cache = ["stale"])
assert apply_step_cache(_pipe(t), mode = "fbcache") == TC_FBCACHE
assert t._diffusers_hook._child_registries_cache is None
def test_invalidate_child_registry_cache_tolerates_absence():
_invalidate_child_registry_cache(types.SimpleNamespace()) # no registry: no-op
reg = types.SimpleNamespace(_child_registries_cache = None)
_invalidate_child_registry_cache(types.SimpleNamespace(_diffusers_hook = reg))
assert reg._child_registries_cache is None

View file

@ -393,3 +393,81 @@ def test_nvfp4_filter_keeps_vision_tower_dense(monkeypatch):
assert ff(object(), "lm_head") is False
assert ff(object(), "model.decoder.wo") is False
assert ff(object(), "model.layers.5.self_attn.q_proj") is True
# ── zero-output-row guard (per-row fp8 NaN protection) ───────────────────────────
class _FakeAmaxVec:
def __init__(self, vals):
self._vals = vals
def __eq__(self, other): # noqa: PLW0642 -- tensor-style elementwise compare
return _FakeAmaxVec([v == other for v in self._vals])
def any(self):
return _FakeScalar(any(self._vals))
class _FakeScalar:
def __init__(self, v):
self._v = v
def item(self):
return self._v
class _FakeWeight:
"""Tensor-shaped stand-in supporting the exact chain the guard runs:
``weight.abs().amax(dim = -1) == 0 -> .any().item()``."""
ndim = 2
def __init__(self, rows):
self._rows = rows
def abs(self):
return _FakeWeight([[abs(v) for v in r] for r in self._rows])
def amax(self, dim = -1):
return _FakeAmaxVec([max(r) for r in self._rows])
def test_weight_zero_output_row_detection():
# A dead output row NaNs torchao's per-row fp8 (scale 0 -> 0/0); SDXL's
# text_encoder_2 (OpenCLIP bigG) really ships one in layers.2.self_attn.out_proj --
# measured: every fp8_dynamic SDXL render was black until the row is kept dense.
zero_row = types.SimpleNamespace(weight = _FakeWeight([[0.1, 0.2], [0.0, 0.0]]))
dense = types.SimpleNamespace(weight = _FakeWeight([[0.1, 0.2], [0.3, 0.0]]))
assert dp._weight_has_zero_output_row(zero_row) is True
assert dp._weight_has_zero_output_row(dense) is False
# Non-2D / absent weights are not the per-row scheme's input: never flagged.
w3 = _FakeWeight([[1.0]])
w3.ndim = 3
assert dp._weight_has_zero_output_row(types.SimpleNamespace(weight = w3)) is False
assert dp._weight_has_zero_output_row(types.SimpleNamespace()) is False
# An unreadable weight falls through to quantize_'s own handling.
class _Boom:
@property
def weight(self):
raise RuntimeError("meta tensor")
assert dp._weight_has_zero_output_row(_Boom()) is False
def test_fp8_dynamic_filter_skips_zero_row_linear(monkeypatch):
# The fp8_dynamic caster must leave a zero-output-row Linear dense while the rest
# of the encoder still quantises (a family-wide deny would forfeit the whole win).
_stub_torch(monkeypatch)
captured: dict = {}
_stub_transformer_quant(monkeypatch, captured)
enc = types.SimpleNamespace(_keep_in_fp32_modules = [])
dp._cast_fp8_dynamic(enc, _target())
ff = captured["filter_fn"]
dead = types.SimpleNamespace(weight = _FakeWeight([[0.5, 0.5], [0.0, 0.0]]))
live = types.SimpleNamespace(weight = _FakeWeight([[0.5, 0.5], [0.5, 0.5]]))
assert ff(dead, "text_model.encoder.layers.2.self_attn.out_proj") is False
assert ff(live, "text_model.encoder.layers.2.mlp.fc1") is True

View file

@ -531,3 +531,85 @@ def test_fp16_accum_allowed_on_fp16_dtype_under_max(monkeypatch):
)
assert applied["fp16_accum"] is True
assert torch.backends.cuda.matmul.allow_fp16_accumulation is True
# ── inductor precision-cast emulation (compile-vs-eager numeric parity) ─────────
def _stub_inductor_config(
monkeypatch,
torch,
*,
emulate = False,
):
"""Attach a fake ``_inductor.config`` to the stubbed torch module (diffusion_speed
resolves it as attributes off the imported torch, never via sys.modules -- so the
real torch._inductor lingering in sys.modules cannot leak into stubbed tests)."""
cfg = types.SimpleNamespace(emulate_precision_casts = emulate)
torch._inductor = types.SimpleNamespace(config = cfg)
return cfg
def test_regional_compile_enables_emulate_precision_casts(monkeypatch):
# Inductor's fused pointwise kernels keep intermediates in fp32 where eager rounds
# to bf16 between ops; over a multi-step denoise that compounds to a visible drift.
# emulate_precision_casts restores eager's rounding at zero measured speed cost, so
# the regional compile path must switch it on.
torch = _stub_torch(monkeypatch)
_stub_gguf_accel(monkeypatch)
cfg = _stub_inductor_config(monkeypatch, torch, emulate = False)
pipe = _Pipe(with_compile = True)
applied = apply_speed_optims(
pipe, _target(), is_gguf = False, family = _family(), speed_mode = SPEED_DEFAULT
)
assert applied["compiled"] is True
assert cfg.emulate_precision_casts is True
def test_snapshot_restores_emulate_precision_casts(monkeypatch):
# The flag is process-global, so the unload path must restore the pre-load value
# exactly like the TF32 / cudnn.benchmark globals.
torch = _stub_torch(monkeypatch)
cfg = _stub_inductor_config(monkeypatch, torch, emulate = False)
snap = snapshot_backend_flags()
assert snap["inductor_emulate_precision_casts"] is False
cfg.emulate_precision_casts = True
restore_backend_flags(snap)
assert cfg.emulate_precision_casts is False
def test_missing_inductor_config_is_tolerated(monkeypatch):
# A build without torch._inductor (or with the flag renamed) must neither break the
# snapshot nor the compile path.
_stub_torch(monkeypatch) # the stub torch has no _inductor attribute
_stub_gguf_accel(monkeypatch)
snap = snapshot_backend_flags()
assert "inductor_emulate_precision_casts" not in snap
pipe = _Pipe(with_compile = True)
applied = apply_speed_optims(
pipe, _target(), is_gguf = False, family = _family(), speed_mode = SPEED_DEFAULT
)
assert applied["compiled"] is True
def test_regional_compile_arms_cache_hook_inners(monkeypatch):
# The production load order engages the step cache BEFORE compile, so the regional
# compile pass must re-arm the already-installed cache hooks with compiled inner
# forwards (otherwise every computed step runs eager under the hook's
# torch.compiler.disable and forfeits the regional compile).
_stub_torch(monkeypatch)
_stub_gguf_accel(monkeypatch)
from core.inference import diffusion_cache as dc_mod
armed = []
monkeypatch.setattr(
dc_mod,
"_compile_hooked_block_inners",
lambda transformer, logger = None: armed.append(transformer) or 1,
)
pipe = _Pipe(with_compile = True)
applied = apply_speed_optims(
pipe, _target(), is_gguf = False, family = _family(), speed_mode = SPEED_DEFAULT
)
assert applied["compiled"] is True
assert armed == [pipe.transformer]