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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
"""Declarative model capabilities for component layerwise offload.
Models declare an ``_offload_plan`` class attribute on the pipeline. Both the
ordinary and distributed layerwise backends consume the same plan instead of
embedding model-specific block paths in backend code.
"""
from __future__ import annotations
from dataclasses import dataclass, field
from torch import nn
@dataclass(frozen=True)
class OffloadPlan:
"""Optional declarative metadata for component layerwise offload.
Models declare this as a class attribute ``_offload_plan`` on the
pipeline class. When present, both layerwise backends use it instead of
model-specific backend branches, making new integrations data-driven.
If not declared, the offloader falls back to
``_layerwise_offload_blocks_attrs`` on each DiT module class.
:func:`~vllm_omni.diffusion.offloader.plan_resolver.resolve_offload_plan`
is the only consumer; backends read the resolved artifact it returns.
Attributes:
block_attrs: Maps DiT path → tuple of block-list attribute names.
e.g. ``{"transformer": ("gen_layers",),
"transformer.language_model": ("layers",)}``
offload_submodules: Maps child name → block-list attribute name,
for large non-DiT submodules within a DiT that should be
independently offloaded with their own hooks.
e.g. ``{"context_encoder": "layers"}``
resident_dit_paths: DiT paths whose leading blocks may be kept on the
device when ``dlo_resident_layers`` is nonzero. Keeping this
model-declared avoids applying a consumer-GPU tuning knob to
auxiliary or dual DiTs unintentionally.
encoder_component_types: Maps encoder paths to public selector types
(currently text_encoder). This declaration is used before the
compatibility name heuristic.
encoder_block_attrs: Maps encoder paths to streamable block-list paths.
encoder_dlo_weight_replication: Encoder paths whose loader-produced
block tensors are identical across the DiT DLO group. Only these
encoders may use multi-rank AllGather transfer; this must not be
declared for encoder-TP shards.
"""
on_demand_component_paths: frozenset[str] = field(default_factory=frozenset)
block_attrs: dict[str, tuple[str, ...]] = field(default_factory=dict)
offload_submodules: dict[str, str] = field(default_factory=dict)
resident_dit_paths: frozenset[str] = field(default_factory=frozenset)
encoder_component_types: dict[str, str] = field(default_factory=dict)
encoder_block_attrs: dict[str, tuple[str, ...]] = field(default_factory=dict)
encoder_dlo_weight_replication: frozenset[str] = field(default_factory=frozenset)
def get_offload_plan(pipeline: nn.Module) -> OffloadPlan | None:
"""Retrieve the OffloadPlan declared by the pipeline, if any."""
return getattr(pipeline, "_offload_plan", None)