Files
hao-ai-lab-FastVideo/v2/models/wan21/loop.py
T
SolitaryThinker 9b8838834c [feat] piecewise CUDA-graph capture/replay at the step boundary (Path A)
Wire the capture/replay lifecycle into the driven-loop step boundary — the
other half of Path A (hand-fused kernels behind the registry + piecewise
cudagraphs, no compiler). Models and tests the correctness-critical control
logic; replay re-runs the current step thunk (CPU models the lifecycle, not the
GPU speedup).

- GraphCapturer on the instance (cross-request cache), wired into
  RuntimeLoopContext.execute and gated by LoopSpec.graph_capture ==
  "breakable_cudagraph". Capture key = (device, arch, loop, shape_sig,
  resident-weight-versions, graph_key). Eager-break for non-capturable (SDE) and
  interceptor-overridden steps. Never executes a stored thunk, so interleaved
  requests can't smear state.
- WorkPlan.capturable / graph_key. wan21 sets capturable=not sde and folds
  compute dtype (shape_sig.dtype) + CFG branch set + expert + scheduler-precision
  into the key — closing a cross-precision key-collision corruption path a
  non-fp32 build would otherwise hit on a real GPU (audit finding).
- Version-in-key auto-invalidation + real eviction: set_weights_version evicts
  the synced component's graphs (duck-typed, so card/ imports no runtime),
  preventing a GPU graph leak across FlowGRPO's per-iteration syncs.
- register_kernel gains the workspace_bytes capture-safety contract (declared in
  the matrix; cuda cells declare real scratch, numpy reference is 0).
- 11 tests: capture-once/replay-many, eager-break (SDE + override), capture ≡
  pure-eager bit-identical, recapture on shape + weight-version change with
  eviction, eager-loop gating, accel-backend capture, and capturer unit tests
  (key discrimination, eager-break, workspace-collision safety net, eviction).

Honestly deferred (bite a real GPU, not the CPU tests): the static-buffer
refactor of the step body, admission budgeting of capture cost (GRAPH_CAPTURE),
and per-card opt-in beyond wan21 — all documented in cudagraph.py + README.

195 tests pass.
2026-07-04 17:15:34 +00:00

152 lines
8.4 KiB
Python

"""WanDenoiseLoop — the canonical driven denoise loop (design_v3 §5, §15a).
Bidirectional video diffusion: N flow-match steps over the full latent. Composed from policies
(CFG / flow-shift / precision / expert routing) — the default decomposition. ``next`` is
kernel-free (it builds the forward+combine+solver thunk); ``advance`` folds the result and,
under the ROLLOUT profile, captures a behavior slice — so the *same* loop serves and rolls out
for RL (design_v3 §10). All per-request state lives in ``LoopState`` (interleave-safe).
"""
from __future__ import annotations
import numpy as np
from ..._enums import ExecutionProfile, WorkUnitKind
from ...loop.contracts import (
Done,
LoopResult,
LoopState,
ResourceRequest,
ShapeSignature,
StepContext,
StepResult,
WorkPlan,
)
from ...platform import FLOW_MATCH_STEP, FLOW_SDE_STEP
from ...request.streams import StreamChunk
from ..backend import LATENT_CHANNELS
def latent_shape(req) -> tuple[int, int, int, int]:
"""Map request geometry to a small (deterministic) latent for the CPU toy backend."""
d = req.diffusion
t = max(1, d.num_frames // 40)
h = max(2, d.height // 120)
w = max(2, d.width // 120)
return (LATENT_CHANNELS, t, h, w)
class WanDenoiseLoop:
def __init__(self, *, loop_id, cfg, flow_shift, precision, expert, cost):
self.loop_id = loop_id
self.cfg = cfg
self.flow_shift = flow_shift
self.precision = precision
self.expert = expert
self.cost = cost
def init(self, req, model, ctx) -> LoopState:
seed = req.diffusion.seed if req.diffusion.seed is not None else 0
rng = np.random.default_rng(seed)
sig = self.flow_shift.build_schedule(req.diffusion.num_steps, req.diffusion.height,
req.diffusion.width, sigmas=req.diffusion.sigmas or None)
shape = latent_shape(req)
x = (rng.standard_normal(shape) * float(sig[0])).astype("float32")
st = LoopState(loop_id=self.loop_id, instance_id=model.card.model_id,
request_id=req.request_id, profile=ctx.profile, rng=rng, seed=seed,
latents={"video": x}, sigmas=[float(s) for s in sig],
timesteps=[float(s) * 1000.0 for s in sig])
st.cond["prompt_embeds"] = ctx.slots.get("text_embeds")
st.cond["negative_prompt_embeds"] = ctx.slots.get("neg_text_embeds")
st.scratch["guidance_scale"] = float(req.diffusion.guidance_scale)
st.scratch["stream_video"] = bool(req.outputs.stream.get("video"))
# FlowGRPO RL rollout: switch the sampler to SDE-with-logprob (else deterministic ODE serve).
st.scratch["sde"] = bool(getattr(req.diffusion, "sde_rollout", False))
st.scratch["sde_noise_scale"] = float(getattr(req.diffusion, "sde_noise_scale", 0.7))
st.plugin_state["cfg"] = {}
return st
def next(self, st: LoopState):
i = st.step_idx
if i >= len(st.sigmas) - 1:
return Done()
sigma_t, sigma_next = st.sigmas[i], st.sigmas[i + 1]
expert_id = self.expert.expert_for(StepContext(i, st.timesteps[i], sigma_t))
sctx = StepContext(step_idx=i, timestep=st.timesteps[i], sigma=sigma_t, active_expert_id=expert_id)
cfg_state = st.plugin_state["cfg"]
branches = self.cfg.branches_this_step(sctx, cfg_state)
x = st.latents["video"]
pe, ne = st.cond["prompt_embeds"], st.cond["negative_prompt_embeds"]
scale = st.scratch["guidance_scale"]
cfg, precision = self.cfg, self.precision
sde, noise_scale, rng = st.scratch.get("sde", False), st.scratch.get("sde_noise_scale", 0.7), st.rng
def run(model, override=None):
# Solver primitives are dispatched through the platform's kernel table: on CPU these
# resolve to the numpy reference; on a GPU/accel backend they resolve to that device's
# kernel — same loop, same StepResult shape (design_v3 §17).
kernels = model.platform.kernels
if override is not None and "noise_pred" in override:
velocity = np.asarray(override["noise_pred"], dtype="float32")
else:
dit = model.component(expert_id)
preds = {b: dit(x, pe if b == "cond" else ne, sigma_t) for b in branches}
velocity = cfg.combine(preds, scale, sctx, cfg_state)
velocity = precision.cast(velocity)
if sde: # FlowGRPO rollout: stochastic + log-prob
noise = rng.standard_normal(x.shape)
x_next, logp, _m, _s = kernels.get(FLOW_SDE_STEP)(
precision.cast(x), velocity, sigma_t, sigma_next, noise=noise, noise_scale=noise_scale)
return StepResult(output={"noise_pred": np.asarray(velocity, dtype="float32"),
"latents": x_next.astype("float32"),
"sde_logprob": logp, "prev": np.asarray(x, dtype="float32")})
x_next = kernels.get(FLOW_MATCH_STEP)(precision.cast(x), velocity, sigma_t, sigma_next)
return StepResult(output={"noise_pred": np.asarray(velocity, dtype="float32"),
"latents": x_next.astype("float32")})
cond_bytes = sum(int(np.asarray(e).nbytes) for e in (pe, ne) if e is not None)
res = ResourceRequest(
compute_seconds=self.cost.predict(int(np.prod(x.shape)), float(len(branches))),
resident_bytes=int(x.nbytes) + cond_bytes, # latents + conditioning held for the loop
peak_activation_bytes=int(x.nbytes)) # one step's transient working buffer
emits = []
if st.scratch.get("stream_video"):
emits.append(StreamChunk(stream_id=st.request_id, modality="video", seq=i,
data=x, preview=True)) # carry the latent as a preview payload
return WorkPlan(
loop_id=self.loop_id, instance_id=st.instance_id, kind=WorkUnitKind.DIFFUSION_STEP,
shape_sig=ShapeSignature(WorkUnitKind.DIFFUSION_STEP, dims=tuple(x.shape),
dtype=precision.compute_dtype, # compute dtype is part of the key
extra=(("cfg", type(cfg).__name__),)),
resources=res, payload={"branch": "combined", "step": i}, run=run,
label=f"wan.denoise.{i}", emits=emits,
# CUDA-graph capture (Path A): the deterministic ODE step is capturable; the stochastic
# SDE rollout step has host RNG / a data-dependent branch, so it must eager-break. The
# op-structure key carries the CFG branch set, active expert, and the scheduler-precision
# flag so a step with a different branch set / expert / solver precision never replays an
# incompatible captured graph. (Compute dtype rides in shape_sig.dtype above.) NOTE: this
# is sound for branch-set/expert-determined policies (ClassicCFG); a policy whose op
# structure forks on other state (PerModalityCFG modality) would need a graph_key hook.
capturable=not sde,
graph_key=(tuple(sorted(branches)), expert_id, precision.scheduler_step_in_fp32))
def advance(self, st: LoopState, result: StepResult) -> LoopState:
st.latents["video"] = result.output["latents"]
if st.profile == ExecutionProfile.ROLLOUT:
i = st.step_idx
rec = {"step": i, "sigma": st.sigmas[i],
"velocity": np.asarray(result.output["noise_pred"]).copy(),
"latents": np.asarray(st.latents["video"]).copy()}
if "sde_logprob" in result.output: # FlowGRPO: capture the PPO log-prob slice
rec.update(sde_logprob=result.output["sde_logprob"],
prev=np.asarray(result.output["prev"]).copy(),
sample=np.asarray(result.output["latents"]).copy(),
sigma_t=st.sigmas[i], sigma_next=st.sigmas[i + 1])
st.trajectory.append(rec)
st.step_idx += 1
return st
def finalize(self, st: LoopState) -> LoopResult:
return LoopResult(outputs={"latents": st.latents["video"]},
metrics={"denoise_steps": float(st.step_idx)},
behavior=st.trajectory or None)