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vllm-omni/vllm_omni/diffusion/models/mammoth_moda2/pipeline_mammothmoda2_dit.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
from __future__ import annotations
from collections.abc import Iterable
from dataclasses import dataclass
from typing import ClassVar
import torch
from diffusers.image_processor import VaeImageProcessor
from diffusers.models.autoencoders.autoencoder_kl import AutoencoderKL
from diffusers.utils.torch_utils import randn_tensor
from torch import nn
from transformers.models.qwen2.modeling_qwen2 import Qwen2RMSNorm
from vllm.logger import init_logger
from vllm.model_executor.models.utils import AutoWeightsLoader, WeightsMapper
from vllm_omni.diffusion.cache.cachedit import (
CacheDiTBackend,
CacheDiTRequestSpec,
RequestScopedCacheDiTRuntime,
)
from vllm_omni.diffusion.data import DiffusionCacheConfig, DiffusionOutput, OmniDiffusionConfig
from vllm_omni.diffusion.distributed.utils import get_local_device
from vllm_omni.diffusion.model_loader.diffusers_loader import DiffusersPipelineLoader
from vllm_omni.diffusion.models.interface import SupportsComponentDiscovery
from vllm_omni.diffusion.request import OmniDiffusionRequest
from vllm_omni.diffusion.worker.request_batch import DiffusionRequestBatch
from vllm_omni.inputs.data import OmniDiffusionSamplingParams
from vllm_omni.transformers_utils.configs.mammoth_moda2 import Mammothmoda2Config
from .mammothmoda2_dit_model import SimpleQFormerImageRefiner, Transformer2DModel
from .rope_real import RotaryPosEmbedReal
from .schedulers import FlowMatchEulerDiscreteScheduler
logger = init_logger(__name__)
# Identifies the pipeline-owned Cache-DiT installation across requests.
_MAMMOTHMODA2_CACHE_DIT_KEY = "mammothmoda2:cache_dit"
def _first_request_value(value: object) -> object:
if isinstance(value, (list, tuple)):
return value[0] if value else None
return value
def get_mammoth_moda2_post_process_func(
_od_config: OmniDiffusionConfig,
):
image_processor = VaeImageProcessor()
def post_process_func(images: torch.Tensor):
return image_processor.postprocess(images)
return post_process_func
def _build_mammoth_config(od_config: OmniDiffusionConfig) -> Mammothmoda2Config:
raw_config = od_config.tf_model_config.to_dict()
if not raw_config:
raise ValueError("MammothModa2 diffusion stage requires the root checkpoint config")
return Mammothmoda2Config(**raw_config)
def _root_weight_source(
od_config: OmniDiffusionConfig,
) -> DiffusersPipelineLoader.ComponentSource:
if not od_config.model:
raise ValueError("MammothModa2 diffusion stage requires a model path")
return DiffusersPipelineLoader.ComponentSource(
model_or_path=od_config.model,
subfolder=None,
revision=od_config.revision,
prefix="",
fall_back_to_pt=True,
)
def _pad_cond_sequence(
embeds: list[torch.Tensor],
masks: list[torch.Tensor],
) -> tuple[torch.Tensor, torch.Tensor]:
"""Right-pad per-request ``[1, T_i, H]`` embeds into ``[B, T_max, H]``.
The transformer derives per-row ``encoder_seq_lengths`` from the boolean
mask, so padding must sit on the right and masked positions are excluded
from the packed joint sequence.
"""
if not embeds:
raise ValueError("Cannot pad an empty conditioning sequence list")
if len(embeds) != len(masks):
raise ValueError(f"Conditioning embeds/mask count mismatch: {len(embeds)} vs {len(masks)}")
# Fast-path for single-item batch: bypass padding tensor allocation
if len(embeds) == 1:
emb0, m0 = embeds[0], masks[0]
if emb0.ndim != 3 or emb0.shape[0] != 1:
raise ValueError(f"Conditioning embeds[0] must be [1, T, H], got {tuple(emb0.shape)}")
if m0.ndim != 2 or m0.shape != emb0.shape[:2]:
raise ValueError(f"Conditioning embeds/mask length mismatch: {tuple(emb0.shape)} vs {tuple(m0.shape)}")
return emb0, m0
hidden = embeds[0].shape[-1]
lengths = [int(e.shape[1]) for e in embeds]
max_len = max(lengths)
# Fast-path for homogeneous lengths: concatenate directly in C++
if all(length == max_len for length in lengths):
for i, (emb, m) in enumerate(zip(embeds, masks)):
if emb.ndim != 3 or emb.shape[0] != 1 or emb.shape[-1] != hidden:
raise ValueError(f"Conditioning embeds[{i}] must be [1, T, {hidden}], got {tuple(emb.shape)}")
if m.ndim != 2 or m.shape[0] != 1 or m.shape[1] != max_len:
raise ValueError(f"Conditioning embeds/mask length mismatch: {tuple(emb.shape)} vs {tuple(m.shape)}")
return torch.cat(embeds, dim=0), torch.cat(masks, dim=0)
out = embeds[0].new_zeros((len(embeds), max_len, hidden))
mask = torch.zeros((len(embeds), max_len), dtype=torch.bool, device=out.device)
for i, (emb, m) in enumerate(zip(embeds, masks)):
if emb.ndim != 3 or emb.shape[0] != 1 or emb.shape[-1] != hidden:
raise ValueError(f"Conditioning embeds[{i}] must be [1, T, {hidden}], got {tuple(emb.shape)}")
if m.ndim != 2 or m.shape[0] != 1 or m.shape[1] != emb.shape[1]:
raise ValueError(f"Conditioning embeds/mask length mismatch: {tuple(emb.shape)} vs {tuple(m.shape)}")
out[i, : emb.shape[1]] = emb[0]
mask[i, : m.shape[1]] = m[0].bool()
return out, mask
def _resolve_request_sampling_and_dims(
prompt: dict,
sampling: OmniDiffusionSamplingParams | None,
request_id: str,
) -> tuple[int, int, float, tuple[float, float], int]:
"""Shared extraction and validation of geometry and sampling knobs."""
dimensions = []
for name in ("height", "width"):
value = DiffusionRequestBatch.get_prompt_field(prompt, name)
if value is None and sampling is not None:
value = getattr(sampling, name, None)
if value is None:
value = 1024
try:
dimensions.append(int(value))
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid image size {name}={value!r} for request {request_id}") from exc
height, width = dimensions
if height <= 0 or width <= 0:
raise ValueError(f"Invalid image size: {height}x{width} for request {request_id}")
if height % 16 != 0 or width % 16 != 0:
raise ValueError(f"Image size must be multiples of 16, got {height}x{width} for request {request_id}")
info = prompt.get("additional_information")
request_info = info if isinstance(info, dict) else {}
extra_args = sampling.extra_args or {} if sampling else {}
guidance = extra_args.get("text_guidance_scale")
if guidance is None and sampling is not None:
guidance = sampling.guidance_scale if sampling.guidance_scale_provided else None
if guidance is None:
guidance = _first_request_value(request_info.get("text_guidance_scale"))
if guidance is None:
guidance = 9.0
try:
text_guidance_scale = float(guidance)
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid text_guidance_scale for request {request_id}") from exc
raw_num_inference_steps = extra_args.get("num_inference_steps")
if raw_num_inference_steps is None and sampling is not None:
raw_num_inference_steps = sampling.num_inference_steps
if raw_num_inference_steps is None:
raw_num_inference_steps = _first_request_value(request_info.get("num_inference_steps"))
if raw_num_inference_steps is None:
raw_num_inference_steps = 50
try:
num_inference_steps = int(raw_num_inference_steps)
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid num_inference_steps for request {request_id}") from exc
if num_inference_steps <= 0:
raise ValueError(f"num_inference_steps must be positive for request {request_id}")
cfg_range = extra_args.get("cfg_range")
if cfg_range is None:
cfg_range = request_info.get("cfg_range")
if cfg_range is None:
cfg_range = [0.0, 1.0]
if not isinstance(cfg_range, (list, tuple)) or len(cfg_range) != 2:
raise ValueError(f"cfg_range requires two values for request {request_id}")
try:
cfg_start, cfg_end = float(cfg_range[0]), float(cfg_range[1])
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"cfg_range requires two values convertible to floats for request {request_id}") from exc
if not 0 <= cfg_start <= cfg_end <= 1:
raise ValueError(f"cfg_range must satisfy 0 <= start <= end <= 1 for request {request_id}")
return height, width, text_guidance_scale, (cfg_start, cfg_end), num_inference_steps
def _resolve_gen_vocab_start_index(od_config: OmniDiffusionConfig | None) -> int:
"""Resolve the visual token threshold through the normalized model configuration."""
if od_config is not None and getattr(od_config, "tf_model_config", None) is not None:
try:
cfg = _build_mammoth_config(od_config)
llm_cfg = getattr(cfg, "llm_config", None)
if llm_cfg is not None:
val = getattr(llm_cfg, "gen_vocab_start_index", None)
if val is not None:
return int(val)
text_cfg = getattr(llm_cfg, "text_config", None)
if text_cfg is not None and getattr(text_cfg, "gen_vocab_start_index", None) is not None:
return int(text_cfg.gen_vocab_start_index)
except Exception:
pass
# Fallback inspection of raw dictionary if _build_mammoth_config fails (e.g. mock test objects)
raw_cfg = od_config.tf_model_config.to_dict()
if isinstance(raw_cfg, dict):
llm_cfg = raw_cfg.get("llm_config")
if isinstance(llm_cfg, dict):
text_cfg = llm_cfg.get("text_config")
if isinstance(text_cfg, dict) and text_cfg.get("gen_vocab_start_index") is not None:
return int(text_cfg["gen_vocab_start_index"])
if llm_cfg.get("gen_vocab_start_index") is not None:
return int(llm_cfg["gen_vocab_start_index"])
return 152064
def _validate_request_for_admission(
request: OmniDiffusionRequest,
od_config: OmniDiffusionConfig | None = None,
gen_vocab_start_index: int | None = None,
) -> tuple[int, int, int]:
"""Validate request at admission time to fail-fast before entering scheduler queue.
Returns (height, width, num_inference_steps).
"""
request_id = request.request_id
prompt = request.prompt if isinstance(request.prompt, dict) else {}
sampling = request.sampling_params
if sampling is not None and getattr(sampling, "num_outputs_per_prompt", 1) != 1:
raise ValueError(
f"MammothModa2 requires num_outputs_per_prompt == 1, got {sampling.num_outputs_per_prompt} "
f"for request {request_id}"
)
if not request.is_dummy_run():
info = prompt.get("additional_information")
if not isinstance(info, dict):
raise ValueError(f"Missing additional_information AR conditions for request {request_id}")
full_hidden_states = info.get("full_hidden_states")
full_token_ids = info.get("full_token_ids")
if not isinstance(full_hidden_states, torch.Tensor) or not isinstance(full_token_ids, list):
raise ValueError(f"Expected full_hidden_states tensor and full_token_ids list for request {request_id}")
try:
answer_start_index = int(info.get("answer_start_index"))
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid answer_start_index for request {request_id}") from exc
if full_hidden_states.ndim != 2:
raise ValueError(f"Expected 2D full_hidden_states for request {request_id}")
if full_hidden_states.shape[0] != len(full_token_ids):
raise ValueError(f"AR hidden-state/token-count mismatch for request {request_id}")
if not 0 <= answer_start_index <= len(full_token_ids):
raise ValueError(f"answer_start_index outside token range for request {request_id}")
try:
int_tokens = [int(token_id) for token_id in full_token_ids]
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid full_token_ids for request {request_id}") from exc
if gen_vocab_start_index is None:
gen_vocab_start_index = _resolve_gen_vocab_start_index(od_config)
answer_tokens = int_tokens[answer_start_index:]
if not any(token_id >= gen_vocab_start_index for token_id in answer_tokens):
raise ValueError(
f"MammothModa2 AR stage produced no visual-token hidden states for request {request_id}; "
f"the DiT stage requires at least one generated visual token. Generated token ids: {answer_tokens[:32]}"
)
height, width, _, _, num_inference_steps = _resolve_request_sampling_and_dims(prompt, sampling, request_id)
return height, width, num_inference_steps
def get_mammoth_moda2_pre_process_func(od_config: OmniDiffusionConfig | None = None):
"""Admission preprocessor: fail-fast per-request validation and grouping.
Validates AR conditions, dimensions, and sampling knobs at admission so
malformed requests are rejected individually with their request_id before
entering the scheduler queue. Admitted requests are assigned a
batch_compatibility_key based on output geometry and inference steps.
"""
gen_vocab_start_index = _resolve_gen_vocab_start_index(od_config)
def pre_process_func(request: OmniDiffusionRequest) -> OmniDiffusionRequest:
height, width, num_inference_steps = _validate_request_for_admission(
request, od_config=od_config, gen_vocab_start_index=gen_vocab_start_index
)
request.batch_compatibility_key = (
"mammoth_moda2_dit",
height,
width,
num_inference_steps,
)
return request
return pre_process_func
@dataclass(frozen=True)
class _MammothRequest:
index: int
request_id: str
full_hidden_states: torch.Tensor
full_token_ids: list[int]
answer_start_index: int
height: int
width: int
text_guidance_scale: float
cfg_range: tuple[float, float]
num_inference_steps: int
seed: int | None
generator: torch.Generator | list[torch.Generator] | None
generator_device: torch.device | str | None = None
@dataclass(frozen=True)
class _RequestConditioning:
text_embeds: torch.Tensor
text_mask: torch.Tensor
image_embeds: torch.Tensor
image_mask: torch.Tensor
class MammothModa2DiTPipeline(nn.Module, SupportsComponentDiscovery):
"""
MammothModa2 DiT + VAE generation stage (non-autoregressive).
This stage expects "image condition token hidden states" from the upstream AR stage,
and outputs image tensors via diffusion transformer + VAE decode.
"""
_dit_modules: ClassVar[list[str]] = ["gen_transformer"]
_encoder_modules: ClassVar[list[str]] = ["gen_image_condition_refiner"]
_vae_modules: ClassVar[list[str]] = ["gen_vae"]
supports_request_batch = True
supports_step_execution = False
# Load only gen_* weights; ignore llm_model.* to prevent loading the entire LLM backbone in the DiT stage.
hf_to_vllm_mapper = WeightsMapper(
orig_to_new_prefix={
"llm_model.": None,
"gen_tokenizer.": None,
}
)
def __init__(self, *, od_config: OmniDiffusionConfig, prefix: str = ""):
super().__init__()
del prefix
self.od_config = od_config
self.device = get_local_device()
self.config = _build_mammoth_config(od_config)
self.weights_sources = [_root_weight_source(od_config)]
# --- Build DiT / VAE modules (names must match checkpoint keys) ---
if self.config.gen_vae_config is None or self.config.gen_dit_config is None:
raise ValueError("Mammothmoda2Config.gen_vae_config / gen_dit_config must not be None")
self.gen_vae = AutoencoderKL.from_config(self.config.gen_vae_config)
self.gen_transformer = Transformer2DModel.from_config(self.config.gen_dit_config)
# llm_config is a Mammothmoda2Qwen2_5_VLConfig which has nested text_config
llm_hidden_size = 0
text_config = self.config.get_text_config()
if text_config is None:
logger.warning("No text config; failed to infer llm_hidden_size.")
elif not hasattr(text_config, "hidden_size"):
logger.warning("Text config exists, but has no hidden_size attribute; failed to infer llm_hidden_size.")
else:
llm_hidden_size = int(text_config.hidden_size or 0)
if llm_hidden_size <= 0:
raise ValueError(
"Failed to infer llm hidden_size from Mammothmoda2Config.llm_config.text_config.hidden_size"
)
self._reinit_caption_embedder(llm_hidden_size)
# Optional image condition Q-Former. Preview stores it as a standalone
# module; Dev stores it under the DiT timestep/caption embedder.
llm_model_type = getattr(self.config.llm_config, "model_type", "")
refiner_config = self.config.gen_image_condition_refiner_config
if refiner_config is not None and llm_model_type == "mammothmoda2_qwen3_vl":
dit_hidden_size = int(self.gen_transformer.hidden_size)
self.gen_transformer.time_caption_embed.image_embedder = SimpleQFormerImageRefiner(
hidden_size=llm_hidden_size,
output_hidden_size=dit_hidden_size,
num_heads=max(1, dit_hidden_size // 128),
**refiner_config,
)
self.gen_image_condition_refiner = None
elif refiner_config is not None:
self.gen_image_condition_refiner = SimpleQFormerImageRefiner(
hidden_size=llm_hidden_size,
**refiner_config,
)
else:
self.gen_image_condition_refiner = None
# Precompute rotary freqs for diffusion transformer
# IMPORTANT: follow upstream mammothmoda: use top-level `config.gen_axes_*`
# (the checkpoint's `gen_dit_config.axes_lens` can be as small as 1024,
# which is insufficient for vLLM dummy-run/cudagraph warmup).
self.gen_freqs_cis = RotaryPosEmbedReal.get_freqs_real(
tuple(self.config.gen_axes_dim_rope),
tuple(self.config.gen_axes_lens),
theta=10000,
)
self._llm_hidden_size = llm_hidden_size
# Cache-DiT lifecycle: the diffusion runner enables the configured
# backend (``cache_backend`` on the deploy YAML stage entry) at startup
# and transfers ownership here via the request-scoped protocol;
# forward() then reconciles per-request state (step count, CFG parity).
# The runner also emits the cache summary when
# ``enable_cache_dit_summary`` is set.
self._cache_dit_runtime = RequestScopedCacheDiTRuntime(self)
self._cache_dit_config: DiffusionCacheConfig | None = None
if str(getattr(od_config, "cache_backend", "") or "").lower() == "cache_dit":
cache_config = od_config.cache_config
self._cache_dit_config = (
cache_config
if isinstance(cache_config, DiffusionCacheConfig)
else DiffusionCacheConfig.from_dict(cache_config or {})
)
def adopt_cache_dit_backend(self, backend: CacheDiTBackend) -> None:
"""Adopt a runner-installed Cache-DiT backend (request-scoped protocol)."""
self._cache_dit_runtime.adopt(backend, installation_key=_MAMMOTHMODA2_CACHE_DIT_KEY)
def is_cache_dit_enabled(self) -> bool:
"""Return the request-scoped Cache-DiT installation state."""
return self._cache_dit_runtime.is_enabled
def _prepare_cache_dit_for_request(self, *, num_inference_steps: int, cfg_active: bool) -> None:
"""Reconcile Cache-DiT hooks with this request before the denoise loop.
cache-dit's separate-CFG accounting assumes exactly two transformer
forwards per denoise step (conditional then unconditional), so CFG
requests refresh the context (per-request step counts vary) while
no-CFG requests run with hooks disabled: their single forward per
step cannot be represented by the parity accounting.
"""
if self._cache_dit_config is None:
return
if not cfg_active:
self._cache_dit_runtime.prepare(None)
return
self._cache_dit_runtime.prepare(
CacheDiTRequestSpec(
installation_key=_MAMMOTHMODA2_CACHE_DIT_KEY,
cache_config=self._cache_dit_config,
num_inference_steps=num_inference_steps,
)
)
def _reinit_caption_embedder(self, in_features: int) -> None:
# Align with upstream Mammothmoda2Model's `reinit_caption_embedder`:
# Use Qwen2RMSNorm(in_features) + Linear(in_features -> out_features).
out_features = int(getattr(self.gen_transformer, "hidden_size", 0) or self.gen_transformer.config.hidden_size)
self.gen_transformer.time_caption_embed.caption_embedder = nn.Sequential(
Qwen2RMSNorm(in_features, eps=1e-5),
nn.Linear(in_features, out_features, bias=True),
)
@staticmethod
def _group_requests(specs: list[_MammothRequest]) -> list[list[int]]:
"""Group co-scheduled requests by (height, width, num_inference_steps).
Preserves arrival order: the first-seen request of each bucket
determines the group's execution order.
"""
buckets: dict[tuple[int, int, int], list[int]] = {}
for idx, spec in enumerate(specs):
key = (spec.height, spec.width, spec.num_inference_steps)
buckets.setdefault(key, []).append(idx)
return list(buckets.values())
def _parse_request(self, req: DiffusionRequestBatch, index: int = 0) -> _MammothRequest:
request = req.requests[index]
request_id = request.request_id
prompt = request.prompt if isinstance(request.prompt, dict) else {}
sampling = request.sampling_params
if sampling is not None and getattr(sampling, "num_outputs_per_prompt", 1) != 1:
raise ValueError(
f"MammothModa2 requires num_outputs_per_prompt == 1, got {sampling.num_outputs_per_prompt} "
f"for request {request_id}"
)
info = prompt.get("additional_information")
if request.is_dummy_run():
gen_start = 152064
if hasattr(self, "config") and hasattr(self.config, "llm_config") and self.config.llm_config is not None:
val = getattr(self.config.llm_config, "gen_vocab_start_index", None)
if val is not None:
gen_start = val
else:
text_cfg = getattr(self.config.llm_config, "text_config", None)
if text_cfg is not None and getattr(text_cfg, "gen_vocab_start_index", None) is not None:
gen_start = text_cfg.gen_vocab_start_index
full_hidden_states = torch.zeros((2, self._llm_hidden_size), dtype=torch.float32)
full_token_ids = [0, int(gen_start)]
answer_start_index = 1
else:
if not isinstance(info, dict):
raise ValueError(f"Missing additional_information AR conditions for request {request_id}")
full_hidden_states = info.get("full_hidden_states")
full_token_ids = info.get("full_token_ids")
if not isinstance(full_hidden_states, torch.Tensor) or not isinstance(full_token_ids, list):
raise ValueError(f"Expected full_hidden_states tensor and full_token_ids list for request {request_id}")
try:
answer_start_index = int(info.get("answer_start_index"))
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid answer_start_index for request {request_id}") from exc
if full_hidden_states.ndim != 2:
raise ValueError(f"Expected 2D full_hidden_states for request {request_id}")
if full_hidden_states.shape[0] != len(full_token_ids):
raise ValueError(f"AR hidden-state/token-count mismatch for request {request_id}")
if not 0 <= answer_start_index <= len(full_token_ids):
raise ValueError(f"answer_start_index outside token range for request {request_id}")
try:
full_token_ids = [int(token_id) for token_id in full_token_ids]
except (TypeError, ValueError, OverflowError) as exc:
raise ValueError(f"Invalid full_token_ids for request {request_id}") from exc
height, width, text_guidance_scale, cfg_range, num_inference_steps = _resolve_request_sampling_and_dims(
prompt, sampling, request_id
)
generator = sampling.generator if sampling else None
if isinstance(generator, list) and len(generator) != 1:
raise ValueError(
f"MammothModa2 single-output request mode requires exactly one generator for request {request_id}"
)
return _MammothRequest(
index=index,
request_id=request_id,
full_hidden_states=full_hidden_states,
full_token_ids=full_token_ids,
answer_start_index=answer_start_index,
height=height,
width=width,
text_guidance_scale=text_guidance_scale,
cfg_range=cfg_range,
num_inference_steps=num_inference_steps,
seed=sampling.seed if sampling else None,
generator=generator,
generator_device=getattr(sampling, "generator_device", None) if sampling else None,
)
def _split_ar_conditions(
self,
*,
full_hidden_states: torch.Tensor,
full_token_ids: list[int],
answer_start_index: int,
) -> tuple[torch.Tensor, torch.Tensor]:
"""Split AR-stage hidden states into text / image condition embeds.
The token ids that distinguish question (text) tokens, generated visual
tokens, and multi-modal placeholder tokens are read from the model config
(``gen_vocab_start_index`` and the vision placeholder token ids), so the
caller no longer needs to pass them. Mirrors the masking the bespoke
MammothModa2 example performed via ar2dit.
"""
gen_vocab_start_index = getattr(self.config.llm_config, "gen_vocab_start_index", None)
if gen_vocab_start_index is None:
text_cfg = getattr(self.config.llm_config, "text_config", None)
gen_vocab_start_index = getattr(text_cfg, "gen_vocab_start_index", 152064)
gen_vocab_start_index = int(gen_vocab_start_index)
cached_visual_ids = getattr(self, "_cached_visual_ids_tensor", None)
if cached_visual_ids is None:
cached_visual_ids = torch.tensor(
[
int(self.config.image_token_id),
int(self.config.video_token_id),
int(self.config.vision_start_token_id),
int(self.config.vision_end_token_id),
],
dtype=torch.long,
)
self._cached_visual_ids_tensor = cached_visual_ids
device = full_hidden_states.device
token_ids = torch.tensor(full_token_ids, dtype=torch.long, device=device)
positions = torch.arange(token_ids.shape[0], device=device)
questions_mask = positions < answer_start_index
answers_mask = ~questions_mask
gen_token_mask = token_ids >= gen_vocab_start_index
visual_ids_device = cached_visual_ids.to(device=device, non_blocking=True)
visual_token_mask = torch.isin(token_ids, visual_ids_device)
text_mask = questions_mask & ~(visual_token_mask | gen_token_mask)
image_mask = answers_mask & gen_token_mask
# Keep the transferred representation compact until the final device/dtype
# conversion in ``forward``. The masks are dtype-independent, and an
# unconditional host-side float32 expansion here would otherwise double both
# the selected-condition staging footprint and BF16 H2D traffic.
text_cond = full_hidden_states[text_mask].contiguous()
image_cond = full_hidden_states[image_mask].contiguous()
return text_cond, image_cond
def _split_request_conditions(self, request: _MammothRequest) -> tuple[torch.Tensor, torch.Tensor]:
"""Split AR hidden states and fail fast before touching model params."""
text_cond, image_cond = self._split_ar_conditions(
full_hidden_states=request.full_hidden_states,
full_token_ids=request.full_token_ids,
answer_start_index=request.answer_start_index,
)
if image_cond.shape[0] == 0:
answer_token_ids = request.full_token_ids[request.answer_start_index :]
raise ValueError(
"MammothModa2 AR stage produced no visual-token hidden states for "
f"request {request.request_id}; the DiT stage requires at least one generated visual token. "
f"Generated token ids: {answer_token_ids[:32]}"
)
return text_cond, image_cond
def _build_conditioning(
self,
text_cond: torch.Tensor,
image_cond: torch.Tensor,
model_device: torch.device,
target_dtype: torch.dtype,
) -> _RequestConditioning:
text_embeds = text_cond.to(device=model_device, dtype=target_dtype, non_blocking=True).contiguous().unsqueeze(0)
text_mask = torch.ones((1, text_embeds.shape[1]), dtype=torch.bool, device=model_device)
image_embeds = (
image_cond.to(device=model_device, dtype=target_dtype, non_blocking=True).contiguous().unsqueeze(0)
)
image_mask = torch.ones((1, image_embeds.shape[1]), dtype=torch.bool, device=model_device)
return _RequestConditioning(
text_embeds=text_embeds,
text_mask=text_mask,
image_embeds=image_embeds,
image_mask=image_mask,
)
@staticmethod
def _make_latent_generators(
specs: list[_MammothRequest],
fallback_device: torch.device,
) -> list[torch.Generator] | None:
generators: list[torch.Generator] = []
for s in specs:
if s.generator is not None:
gen = s.generator[0] if isinstance(s.generator, list) else s.generator
elif s.seed is not None:
device = s.generator_device or fallback_device
gen = torch.Generator(device=device).manual_seed(s.seed)
else:
return None
generators.append(gen)
return generators
def _denoise_group(
self,
specs: list[_MammothRequest],
conds: list[_RequestConditioning],
model_device: torch.device,
) -> list[torch.Tensor]:
batch = len(specs)
height = specs[0].height
width = specs[0].width
num_inference_steps = specs[0].num_inference_steps
target_dtype = conds[0].text_embeds.dtype
# Conditioning collation. Token order is text-then-image per request,
# so concatenate first and right-pad the combined sequence.
nested_image_embedder = getattr(self.gen_transformer.time_caption_embed, "image_embedder", None)
if self.gen_image_condition_refiner is not None:
image_embeds, image_mask = _pad_cond_sequence(
[c.image_embeds for c in conds],
[c.image_mask for c in conds],
)
# Apply optional refiner ONLY on image condition tokens.
if image_embeds.shape[1] > 0:
image_embeds = self.gen_image_condition_refiner(image_embeds, ~image_mask.bool())
refined_image_mask = torch.ones(
image_embeds.shape[:2],
dtype=torch.bool,
device=image_embeds.device,
)
seq_embeds = []
seq_masks = []
for i, c in enumerate(conds):
cur_img_embed = image_embeds[i : i + 1]
cur_img_mask = refined_image_mask[i : i + 1]
seq_embeds.append(torch.cat([c.text_embeds, cur_img_embed], dim=1))
seq_masks.append(torch.cat([c.text_mask, cur_img_mask], dim=1))
prompt_embeds, prompt_attention_mask = _pad_cond_sequence(seq_embeds, seq_masks)
ar_image_embeds = None
ar_image_attention_mask = None
elif nested_image_embedder is not None:
prompt_embeds, prompt_attention_mask = _pad_cond_sequence(
[c.text_embeds for c in conds],
[c.text_mask for c in conds],
)
ar_image_embeds, ar_image_attention_mask = _pad_cond_sequence(
[c.image_embeds for c in conds],
[c.image_mask for c in conds],
)
else:
prompt_embeds, prompt_attention_mask = _pad_cond_sequence(
[torch.cat([c.text_embeds, c.image_embeds], dim=1) for c in conds],
[torch.cat([c.text_mask, c.image_mask], dim=1) for c in conds],
)
ar_image_embeds = None
ar_image_attention_mask = None
# Empty unconditional prompt for classifier-free guidance, shared by
# all rows; rows that never take the CFG branch select their cond
# prediction directly via torch.where below.
needs_uncond = any(s.text_guidance_scale > 1.0 for s in specs)
negative_prompt_embeds = None
negative_prompt_attention_mask = None
if needs_uncond:
hidden_size = int(prompt_embeds.shape[-1])
negative_prompt_embeds = torch.zeros(
(batch, 0, hidden_size),
dtype=target_dtype,
device=model_device,
)
negative_prompt_attention_mask = torch.zeros(
(batch, 0),
dtype=torch.bool,
device=model_device,
)
vae_scale_factor = 16
latent_channels = int(self.gen_transformer.config.in_channels)
shape = (batch, latent_channels, 2 * height // vae_scale_factor, 2 * width // vae_scale_factor)
single_shape = (1, latent_channels, 2 * height // vae_scale_factor, 2 * width // vae_scale_factor)
generators = self._make_latent_generators(specs, model_device)
if generators is not None:
noise_list = []
for gen in generators:
gen_device = gen.device if hasattr(gen, "device") else model_device
n = randn_tensor(single_shape, generator=gen, device=gen_device, dtype=target_dtype)
noise_list.append(n.to(device=model_device))
latents = torch.cat(noise_list, dim=0)
else:
latents = randn_tensor(shape, device=model_device, dtype=target_dtype)
scheduler = FlowMatchEulerDiscreteScheduler()
scheduler.set_timesteps(
num_inference_steps=num_inference_steps,
device=model_device,
num_tokens=latents.shape[-2] * latents.shape[-1],
)
scale_vec = torch.tensor(
[s.text_guidance_scale for s in specs],
device=model_device,
dtype=target_dtype,
).view(batch, 1, 1, 1)
cfg_specs = [(s.text_guidance_scale > 1.0, float(s.cfg_range[0]), float(s.cfg_range[1])) for s in specs]
total_steps = max(1, len(scheduler.timesteps))
any_cfg_active = any(s.text_guidance_scale > 1.0 for s in specs)
self._prepare_cache_dit_for_request(
num_inference_steps=total_steps,
cfg_active=any_cfg_active,
)
requires_paired_cfg = self._cache_dit_runtime.is_enabled and getattr(
self, "_cache_dit_requires_paired_cfg", False
)
# Precompute mixed-CFG active masks across timesteps to avoid CPU list
# comprehensions and H2D copies in the step loop.
precomputed_active_masks = None
all_active_per_step = None
any_active_per_step = None
if needs_uncond:
precomputed_active_masks = torch.empty((total_steps, batch, 1, 1, 1), device=model_device, dtype=torch.bool)
all_active_per_step = []
any_active_per_step = []
for step_idx in range(total_steps):
frac = step_idx / total_steps
step_mask = [is_active and (lo <= frac <= hi) for is_active, lo, hi in cfg_specs]
all_active_per_step.append(all(step_mask))
any_active_per_step.append(any(step_mask))
mask_t = torch.tensor(step_mask, device=model_device, dtype=torch.bool)
precomputed_active_masks[step_idx] = mask_t.view(batch, 1, 1, 1)
# Precompute timesteps in latent dtype to eliminate per-step cast overhead
timesteps_dtype = scheduler.timesteps.to(latents.dtype)
# Run diffusion loop (CFG supported when text_guidance_scale > 1.0)
for i, t in enumerate(scheduler.timesteps):
timestep = timesteps_dtype[i].expand(batch)
model_pred = self.gen_transformer(
hidden_states=latents,
timestep=timestep,
text_hidden_states=prompt_embeds,
text_attention_mask=prompt_attention_mask,
ref_image_hidden_states=None,
ar_image_hidden_states=ar_image_embeds,
ar_image_attention_mask=ar_image_attention_mask,
freqs_cis=self.gen_freqs_cis,
)
run_uncond = (any_active_per_step is not None and any_active_per_step[i]) if needs_uncond else False
if requires_paired_cfg and negative_prompt_embeds is not None:
run_uncond = True
if run_uncond:
model_pred_uncond = self.gen_transformer(
hidden_states=latents,
timestep=timestep,
text_hidden_states=negative_prompt_embeds,
text_attention_mask=negative_prompt_attention_mask,
ref_image_hidden_states=None,
freqs_cis=self.gen_freqs_cis,
)
# Fused CFG blend: torch.lerp fuses (uncond + scale * (cond - uncond)) into 1 kernel
blended = torch.lerp(model_pred_uncond, model_pred, scale_vec)
if all_active_per_step is not None and all_active_per_step[i]:
# Fast path: all requests in the batch are active.
model_pred = blended
else:
# Inactive rows keep their conditional prediction exactly:
# gating the blend with torch.where avoids propagating
# uncond-branch NaN/rounding into CFG-free rows.
active_tensor = precomputed_active_masks[i]
model_pred = torch.where(active_tensor, blended, model_pred)
latents = scheduler.step(model_pred, t, latents, return_dict=False)[0]
latents = latents.to(dtype=target_dtype)
# VAE decode (in-place scaling to reduce peak VRAM before decode)
if self.gen_vae.config.scaling_factor is not None:
latents.div_(self.gen_vae.config.scaling_factor)
if self.gen_vae.config.shift_factor is not None:
latents.add_(self.gen_vae.config.shift_factor)
vae_dtype = next(self.gen_vae.parameters()).dtype
image = self.gen_vae.decode(latents.to(dtype=vae_dtype), return_dict=False)[0] # [B, C, H, W]
return [image[i : i + 1] for i in range(batch)]
@torch.inference_mode()
def forward(self, req: DiffusionRequestBatch) -> list[DiffusionOutput]:
specs = [self._parse_request(req, i) for i in range(req.num_reqs)]
# Validate AR conditions before touching model parameters so malformed
# requests fail fast instead of surfacing device/dtype errors.
raw_conds = [self._split_request_conditions(spec) for spec in specs]
model_device = next(self.parameters()).device
if self.gen_image_condition_refiner is not None:
target_dtype = next(self.gen_image_condition_refiner.parameters()).dtype
else:
target_dtype = next(self.gen_transformer.parameters()).dtype
conds = [
self._build_conditioning(text_cond, image_cond, model_device, target_dtype)
for text_cond, image_cond in raw_conds
]
groups = self._group_requests(specs)
if len(groups) == 1 and len(groups[0]) == len(specs):
images = self._denoise_group(specs, conds, model_device)
return [DiffusionOutput(output=img) for img in images]
outputs: list[DiffusionOutput | None] = [None] * len(specs)
for group in groups:
images = self._denoise_group(
[specs[i] for i in group],
[conds[i] for i in group],
model_device,
)
for index, image in zip(group, images):
outputs[index] = DiffusionOutput(output=image)
if any(output is None for output in outputs):
raise RuntimeError("DiT batching produced no image for at least one scheduled request")
return [output for output in outputs if output is not None]
def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
loader = AutoWeightsLoader(self)
return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)