sgl-project--sglang/python/sglang/multimodal_gen/runtime/cache/cache_dit_integration.py

# SPDX-License-Identifier: Apache-2.0
"""
cache-dit integration module for SGLang DiT pipelines.

This module provides helper functions to enable cache-dit acceleration
on transformer modules in SGLang's modular pipeline architecture.
"""

from dataclasses import dataclass
from typing import List, Optional

import torch
import torch.distributed as dist

from sglang.multimodal_gen.runtime.distributed.parallel_state import (
    get_ring_parallel_world_size,
    get_tp_world_size,
    get_ulysses_parallel_world_size,
)
from sglang.multimodal_gen.runtime.utils.logging_utils import init_logger

logger = init_logger(__name__)

import cache_dit
from cache_dit import (
    BlockAdapter,
    DBCacheConfig,
    ForwardPattern,
    ParamsModifier,
    TaylorSeerCalibratorConfig,
    steps_mask,
)
from cache_dit.caching.block_adapters import BlockAdapterRegister
from cache_dit.parallelism import ParallelismBackend, ParallelismConfig

from sglang.multimodal_gen.runtime.distributed.parallel_state import get_dit_group

_original_similarity = None


def _patch_cache_dit_similarity():
    from cache_dit.caching.cache_contexts import cache_manager

    global _original_similarity
    if _original_similarity is not None:
        return

    _original_similarity = cache_manager.CachedContextManager.similarity

    def patched_similarity(self, t1, t2, *, threshold, parallelized=False, prefix="Fn"):
        if not parallelized:
            return _original_similarity(
                self,
                t1,
                t2,
                threshold=threshold,
                parallelized=parallelized,
                prefix=prefix,
            )

        sp_group = getattr(self, "_sglang_sp_group", None)
        tp_group = getattr(self, "_sglang_tp_group", None)
        tp_sp_group = getattr(self, "_sglang_tp_sp_group", None)
        target_group = tp_sp_group or sp_group or tp_group

        if target_group is None:
            return _original_similarity(
                self,
                t1,
                t2,
                threshold=threshold,
                parallelized=parallelized,
                prefix=prefix,
            )

        # Adapted from https://github.com/vipshop/cache-dit/blob/main/src/cache_dit/caching/cache_contexts/cache_manager.py#L495-L523
        condition_thresh = self.get_important_condition_threshold()
        if condition_thresh > 0.0:
            raw_diff = (t1 - t2).abs()
            token_m_df = raw_diff.mean(dim=-1)
            token_m_t1 = t1.abs().mean(dim=-1)
            token_diff = token_m_df / token_m_t1
            condition = token_diff > condition_thresh
            if condition.sum() > 0:
                condition = condition.unsqueeze(-1).expand_as(raw_diff)
                mean_diff = raw_diff[condition].mean()
                mean_t1 = t1[condition].abs().mean()
            else:
                mean_diff = (t1 - t2).abs().mean()
                mean_t1 = t1.abs().mean()
        else:
            mean_diff = (t1 - t2).abs().mean()
            mean_t1 = t1.abs().mean()

        dist.all_reduce(mean_diff, op=dist.ReduceOp.AVG, group=target_group)
        dist.all_reduce(mean_t1, op=dist.ReduceOp.AVG, group=target_group)

        diff = (mean_diff / mean_t1).item()
        self.add_residual_diff(diff)
        return diff < threshold

    cache_manager.CachedContextManager.similarity = patched_similarity


def _build_parallelism_config(
    sp_group: Optional[torch.distributed.ProcessGroup],
    tp_group: Optional[torch.distributed.ProcessGroup],
):
    if sp_group is None and tp_group is None:
        return None

    ulysses_size = None
    ring_size = None
    if sp_group is not None:
        ulysses_size = get_ulysses_parallel_world_size()
        ring_size = get_ring_parallel_world_size()

    tp_size = None
    if tp_group is not None:
        tp_size = get_tp_world_size()

    return ParallelismConfig(
        backend=ParallelismBackend.AUTO,
        ulysses_size=ulysses_size,
        ring_size=ring_size,
        tp_size=tp_size,
    )


def _mark_transformer_parallelized(transformer, config, sp_group, tp_group):
    if config is None:
        return

    transformer._is_parallelized = True
    transformer._parallelism_config = config


def get_scm_mask(
    preset: str,
    num_inference_steps: int,
    compute_bins: Optional[List[int]] = None,
    cache_bins: Optional[List[int]] = None,
) -> Optional[List[int]]:
    """
    Get SCM mask using cache-dit's steps_mask().

    This is a thin wrapper that delegates to cache-dit's built-in
    steps_mask() function which handles all presets and scaling logic.

    Args:
        preset: Preset name ("none", "slow", "medium", "fast", "ultra").
        compute_bins: Custom compute bins (overrides preset).
        cache_bins: Custom cache bins (overrides preset).

    Returns:
        SCM mask list (1=compute, 0=cache), or None if disabled.
    """
    if preset == "none" and not (compute_bins and cache_bins):
        return None

    # Use cache-dit's steps_mask() directly
    mask = steps_mask(
        compute_bins=compute_bins,
        cache_bins=cache_bins,
        total_steps=num_inference_steps,
        mask_policy=preset if preset != "none" else "medium",
    )

    compute_count = sum(mask)
    cache_count = len(mask) - compute_count
    logger.info(
        "SCM: generated mask with %d compute steps, %d cache steps (preset=%s)",
        compute_count,
        cache_count,
        preset,
    )

    return mask


@dataclass
class CacheDitConfig:
    """Configuration for cache-dit integration.

    Attributes:
        enabled: Whether to enable cache-dit acceleration.
        Fn_compute_blocks: Number of first blocks to always compute (DBCache F).
        Bn_compute_blocks: Number of last blocks to always compute (DBCache B).
        max_warmup_steps: Number of warmup steps before caching starts (DBCache W).
        residual_diff_threshold: Threshold for residual difference (DBCache R).
        max_continuous_cached_steps: Maximum consecutive cached steps (DBCache MC).
        enable_taylorseer: Whether to enable TaylorSeer calibrator.
        taylorseer_order: Order of Taylor expansion (1 or 2).
        num_inference_steps: Total number of inference steps (required for transformer-only mode).
        steps_computation_mask: Binary mask for step-level caching (1=compute, 0=cache).
            Generated by get_scm_mask() (wrapper around cache_dit.steps_mask()).
        steps_computation_policy: Caching policy for SCM ("dynamic" or "static").
    """

    enabled: bool = False
    Fn_compute_blocks: int = 1
    Bn_compute_blocks: int = 0
    # Use 4 as default warmup steps instead of 8 in cache-dit, thus making
    # DBCache work for few steps distilled models, e.g., Z-Image w/ 8-steps.
    max_warmup_steps: int = 4
    # Use a relatively higher residual diff threshold (namely, 0.24) as default
    # to allow more aggressive caching due to we have already applied max continuous
    # cached steps limit, otherwise, we should use a lower threshold here like 0.12.
    residual_diff_threshold: float = 0.24
    max_continuous_cached_steps: int = 3
    # TaylorSeer is not suitable for few steps distilled models, so, we choose
    # to disable it by default. Reference:
    # - From Reusing to Forecasting: Accelerating Diffusion Models with TaylorSeers,
    #   https://arxiv.org/pdf/2503.06923
    # - FoCa: Forecast then Calibrate: Feature Caching as ODE for Efficient
    #   Diffusion Transformers, https://arxiv.org/pdf/2508.16211
    enable_taylorseer: bool = False
    taylorseer_order: int = 1
    num_inference_steps: Optional[int] = None
    # SCM fields (generated by _maybe_enable_cache_dit from env configuration)
    steps_computation_mask: Optional[List[int]] = None
    steps_computation_policy: str = "dynamic"


@dataclass(frozen=True)
class DualTransformerBlockAdapterSpec:
    """BlockAdapter metadata for dual-transformer DiT pipelines.

    This describes the cache-dit-facing structure of a pair of transformers.
    The denoising loop semantics live in DenoisingStage; this spec only covers
    how cache-dit should find blocks and interpret each block's forward.
    """

    blocks_attr: tuple[str, str]
    blocks_name: Optional[List[str]]
    forward_pattern: List[ForwardPattern]
    check_forward_pattern: bool
    check_num_outputs: bool
    has_separate_cfg: bool


DUAL_TRANSFORMER_BLOCK_ADAPTER_SPECS: dict[str, DualTransformerBlockAdapterSpec] = {
    "wan2.2": DualTransformerBlockAdapterSpec(
        blocks_attr=("blocks", "blocks"),
        blocks_name=None,
        forward_pattern=[ForwardPattern.Pattern_2, ForwardPattern.Pattern_2],
        check_forward_pattern=True,
        check_num_outputs=False,
        has_separate_cfg=True,
    ),
    "ideogram4": DualTransformerBlockAdapterSpec(
        blocks_attr=("layers", "layers"),
        blocks_name=["layers", "layers"],
        forward_pattern=[ForwardPattern.Pattern_3, ForwardPattern.Pattern_3],
        check_forward_pattern=False,
        check_num_outputs=False,
        has_separate_cfg=False,
    ),
}


# Custom BlockAdapter for DiT models absent from cache-dit's BlockAdapterRegister.
# Value: (blocks attr, forward_pattern). forward_pattern must
# match the block's forward signature (see cache_dit.ForwardPattern; e.g., ERNIE
# uses Pattern_3). has_separate_cfg follows the run (passed by
# enable_cache_on_transformer); cache-dit auto-resolves the remaining
# fields.
_CUSTOM_BLOCK_ADAPTER_SPECS: dict[str, tuple[str, ForwardPattern]] = {
    "ErnieImageTransformer2DModel": ("layers", ForwardPattern.Pattern_3),
    "Krea2Transformer2DModel": ("transformer_blocks", ForwardPattern.Pattern_3),
}


def _build_custom_block_adapter(
    transformer: torch.nn.Module,
    has_separate_cfg: bool = False,
) -> Optional[BlockAdapter]:
    """Build a manual BlockAdapter for a model absent from cache-dit's registry,
    or None if the class is unknown."""
    spec = _CUSTOM_BLOCK_ADAPTER_SPECS.get(transformer.__class__.__name__)
    if spec is None:
        return None
    blocks_attr, forward_pattern = spec
    blocks = getattr(transformer, blocks_attr, None)
    if blocks is None:
        raise ValueError(
            f"Transformer {transformer.__class__.__name__} has no attribute "
            f"{blocks_attr!r} for cache-dit blocks."
        )
    return BlockAdapter(
        transformer=transformer,
        blocks=blocks,
        forward_pattern=forward_pattern,
        has_separate_cfg=has_separate_cfg,
    )


def enable_cache_on_transformer(
    transformer: torch.nn.Module,
    config: CacheDitConfig,
    model_name: str = "transformer",
    sp_group: Optional[torch.distributed.ProcessGroup] = None,
    tp_group: Optional[torch.distributed.ProcessGroup] = None,
    has_separate_cfg: bool = False,
) -> torch.nn.Module:
    """Enable cache-dit on a transformer module, by wrapping the module with cache-dit

    This function enables cache-dit acceleration using the BlockAdapterRegister
    for pre-registered models

    Args:
        model_name: Name of the model for logging purposes.
        sp_group: Sequence parallel process group (for Ulysses/Ring).
        tp_group: Tensor parallel process group.
        has_separate_cfg: Whether the run issues separate conditional/unconditional
            passes per step (CFG). Used by custom adapters (ERNIE, Krea-2); a
            mismatch only disables caching, never corrupts output.

    """
    if not config.enabled:
        return transformer

    if config.num_inference_steps is None:
        raise ValueError(
            "num_inference_steps is required for transformer-only mode. "
            "Please provide it in CacheDitConfig."
        )

    # Prefer the standard path (transformer pre-registered in cache-dit). For
    # models absent from the registry, fall back to a manual BlockAdapter (see
    # _build_custom_block_adapter).
    custom_adapter = None
    if not BlockAdapterRegister.is_supported(transformer):
        custom_adapter = _build_custom_block_adapter(
            transformer, has_separate_cfg=has_separate_cfg
        )
        if custom_adapter is None:
            transformer_cls_name = transformer.__class__.__name__
            raise ValueError(
                f"{transformer_cls_name} is not officially supported by cache-dit. "
                "Supported cache-dit DiT families include Flux, QwenImage, HunyuanDiT, "
                "HunyuanVideo, Wan, CogVideoX, Mochi, and others. "
                "Please ensure your transformer belongs to one of these families or "
                "define a custom BlockAdapter."
            )

    # Build cache config (including SCM fields if provided)
    cache_config = DBCacheConfig(
        num_inference_steps=config.num_inference_steps,
        Fn_compute_blocks=config.Fn_compute_blocks,
        Bn_compute_blocks=config.Bn_compute_blocks,
        max_warmup_steps=config.max_warmup_steps,
        residual_diff_threshold=config.residual_diff_threshold,
        max_continuous_cached_steps=config.max_continuous_cached_steps,
        # SCM fields
        steps_computation_mask=config.steps_computation_mask,
        steps_computation_policy=config.steps_computation_policy,
    )

    # Build calibrator config if TaylorSeer is enabled
    calibrator_config = None
    if config.enable_taylorseer:
        calibrator_config = TaylorSeerCalibratorConfig(
            taylorseer_order=config.taylorseer_order,
        )

    # Enable cache-dit on the transformer
    logger.info(
        "Enabling cache-dit on %s with config: Fn=%d, Bn=%d, W=%d, R=%.2f, MC=%d, "
        "TaylorSeer=%s (order=%d), steps=%d",
        model_name,
        config.Fn_compute_blocks,
        config.Bn_compute_blocks,
        config.max_warmup_steps,
        config.residual_diff_threshold,
        config.max_continuous_cached_steps,
        config.enable_taylorseer,
        config.taylorseer_order,
        config.num_inference_steps,
    )

    # Log SCM configuration if enabled
    if config.steps_computation_mask:
        compute_steps = sum(config.steps_computation_mask)
        cache_steps = len(config.steps_computation_mask) - compute_steps
        logger.info(
            "SCM enabled: %d compute steps, %d cache steps, policy=%s",
            compute_steps,
            cache_steps,
            config.steps_computation_policy,
        )

    parallelism_config = _build_parallelism_config(sp_group, tp_group)
    if parallelism_config is not None:
        _patch_cache_dit_similarity()

    _mark_transformer_parallelized(transformer, parallelism_config, sp_group, tp_group)

    # Custom path: pass a pre-built BlockAdapter, bypassing the registry.
    # Standard path: let enable_cache discover the registered adapter.
    target = transformer
    if custom_adapter is not None:
        target = custom_adapter
        logger.info(
            "Enabling cache-dit on %s via custom BlockAdapter (%s).",
            model_name,
            custom_adapter.forward_pattern,
        )
    cache_dit.enable_cache(
        target,
        cache_config=cache_config,
        calibrator_config=calibrator_config,
        parallelism_config=None,
    )

    if parallelism_config is not None:
        context_manager = getattr(transformer, "_context_manager", None)
        if context_manager is not None:
            context_manager._sglang_sp_group = sp_group
            context_manager._sglang_tp_group = tp_group
            # In mixed TP + SP (Ulysses/Ring) mode, cache-dit decisions must be consistent
            # across the full TP×SP model-parallel slice. Prefer using SGLang's DIT group
            # as a conservative superset group; fallback to None.
            tp_sp_group = None
            if sp_group is not None and tp_group is not None:
                tp_sp_group = get_dit_group()

            context_manager._sglang_tp_sp_group = tp_sp_group

    return transformer


def enable_cache_on_dual_transformer(
    transformer: torch.nn.Module,
    transformer_2: torch.nn.Module,
    primary_config: CacheDitConfig,
    secondary_config: CacheDitConfig,
    model_name: str = "wan2.2",
    sp_group: Optional[torch.distributed.ProcessGroup] = None,
    tp_group: Optional[torch.distributed.ProcessGroup] = None,
) -> tuple[torch.nn.Module, torch.nn.Module]:
    """Enable cache-dit on dual transformers using BlockAdapter.

    For models with two transformers, cache-dit requires enabling cache on both
    simultaneously via BlockAdapter. The two transformers may be split by denoising
    range, or run as paired conditional/unconditional branches. This cannot be done
    by calling enable_cache separately on each transformer.

    Args:
        primary_config: CacheDitConfig for primary transformer.
        secondary_config: CacheDitConfig for secondary transformer.
        sp_group: Sequence parallel process group (for Ulysses/Ring).
        tp_group: Tensor parallel process group.
    """
    adapter_spec = DUAL_TRANSFORMER_BLOCK_ADAPTER_SPECS.get(model_name)
    if adapter_spec is None:
        raise ValueError(
            f"Dual-transformer cache-dit is only supported for "
            f"{sorted(DUAL_TRANSFORMER_BLOCK_ADAPTER_SPECS)}, got {model_name}."
        )

    if not primary_config.enabled:
        return transformer, transformer_2

    if primary_config.num_inference_steps is None:
        raise ValueError(
            "num_inference_steps is required for dual-transformer mode. "
            "Please provide it in CacheDitConfig."
        )

    # Build DBCacheConfig for primary transformer
    primary_cache_config = DBCacheConfig(
        num_inference_steps=primary_config.num_inference_steps,
        Fn_compute_blocks=primary_config.Fn_compute_blocks,
        Bn_compute_blocks=primary_config.Bn_compute_blocks,
        max_warmup_steps=primary_config.max_warmup_steps,
        residual_diff_threshold=primary_config.residual_diff_threshold,
        max_continuous_cached_steps=primary_config.max_continuous_cached_steps,
        steps_computation_mask=primary_config.steps_computation_mask,
        steps_computation_policy=primary_config.steps_computation_policy,
    )

    # Build DBCacheConfig for secondary transformer
    secondary_cache_config = DBCacheConfig(
        num_inference_steps=secondary_config.num_inference_steps,
        Fn_compute_blocks=secondary_config.Fn_compute_blocks,
        Bn_compute_blocks=secondary_config.Bn_compute_blocks,
        max_warmup_steps=secondary_config.max_warmup_steps,
        residual_diff_threshold=secondary_config.residual_diff_threshold,
        max_continuous_cached_steps=secondary_config.max_continuous_cached_steps,
        steps_computation_mask=secondary_config.steps_computation_mask,
        steps_computation_policy=secondary_config.steps_computation_policy,
    )

    # Build calibrator configs if TaylorSeer is enabled
    primary_calibrator = None
    if primary_config.enable_taylorseer:
        primary_calibrator = TaylorSeerCalibratorConfig(
            taylorseer_order=primary_config.taylorseer_order,
        )

    secondary_calibrator = None
    if secondary_config.enable_taylorseer:
        secondary_calibrator = TaylorSeerCalibratorConfig(
            taylorseer_order=secondary_config.taylorseer_order,
        )

    # Build ParamsModifier for each transformer
    primary_modifier = ParamsModifier(
        cache_config=primary_cache_config,
        calibrator_config=primary_calibrator,
    )
    secondary_modifier = ParamsModifier(
        cache_config=secondary_cache_config,
        calibrator_config=secondary_calibrator,
    )

    # Log configuration
    logger.info(
        "Enabling cache-dit on %s dual transformers with BlockAdapter",
        model_name,
    )
    logger.info(
        "  Primary (transformer): Fn=%d, Bn=%d, W=%d, R=%.2f, MC=%d, TaylorSeer=%s",
        primary_config.Fn_compute_blocks,
        primary_config.Bn_compute_blocks,
        primary_config.max_warmup_steps,
        primary_config.residual_diff_threshold,
        primary_config.max_continuous_cached_steps,
        primary_config.enable_taylorseer,
    )
    logger.info(
        "  Secondary transformer: Fn=%d, Bn=%d, W=%d, R=%.2f, MC=%d, TaylorSeer=%s",
        secondary_config.Fn_compute_blocks,
        secondary_config.Bn_compute_blocks,
        secondary_config.max_warmup_steps,
        secondary_config.residual_diff_threshold,
        secondary_config.max_continuous_cached_steps,
        secondary_config.enable_taylorseer,
    )

    # Log SCM configuration if enabled
    if primary_config.steps_computation_mask:
        compute_steps = sum(primary_config.steps_computation_mask)
        cache_steps = len(primary_config.steps_computation_mask) - compute_steps
        logger.info(
            "  SCM enabled for primary transformer: %d compute steps, %d cache steps, policy=%s",
            compute_steps,
            cache_steps,
            primary_config.steps_computation_policy,
        )
    if secondary_config.steps_computation_mask:
        compute_steps = sum(secondary_config.steps_computation_mask)
        cache_steps = len(secondary_config.steps_computation_mask) - compute_steps
        logger.info(
            "  SCM enabled for secondary transformer: %d compute steps, %d cache steps, policy=%s",
            compute_steps,
            cache_steps,
            secondary_config.steps_computation_policy,
        )

    parallelism_config = _build_parallelism_config(sp_group, tp_group)
    if parallelism_config is not None:
        _patch_cache_dit_similarity()

    _mark_transformer_parallelized(transformer, parallelism_config, sp_group, tp_group)
    _mark_transformer_parallelized(
        transformer_2, parallelism_config, sp_group, tp_group
    )

    transformer_blocks_attr, transformer_2_blocks_attr = adapter_spec.blocks_attr
    transformer_blocks = getattr(transformer, transformer_blocks_attr, None)
    transformer_2_blocks = getattr(transformer_2, transformer_2_blocks_attr, None)
    if transformer_blocks is None or transformer_2_blocks is None:
        raise ValueError(
            f"Dual transformers for {model_name} must expose cache-dit block "
            f"attributes {adapter_spec.blocks_attr}. "
            f"transformer has {transformer_blocks_attr}: "
            f"{transformer_blocks is not None}, secondary transformer has "
            f"{transformer_2_blocks_attr}: {transformer_2_blocks is not None}"
        )

    cache_dit.enable_cache(
        BlockAdapter(
            transformer=[transformer, transformer_2],
            blocks=[transformer_blocks, transformer_2_blocks],
            blocks_name=adapter_spec.blocks_name,
            forward_pattern=adapter_spec.forward_pattern,
            params_modifiers=[primary_modifier, secondary_modifier],
            check_forward_pattern=adapter_spec.check_forward_pattern,
            check_num_outputs=adapter_spec.check_num_outputs,
            has_separate_cfg=adapter_spec.has_separate_cfg,
        ),
        parallelism_config=None,
    )

    if parallelism_config is not None:
        for t in [transformer, transformer_2]:
            context_manager = getattr(t, "_context_manager", None)
            if context_manager is not None:
                context_manager._sglang_sp_group = sp_group
                context_manager._sglang_tp_group = tp_group
                tp_sp_group = None
                if sp_group is not None and tp_group is not None:
                    try:
                        tp_sp_group = get_dit_group()
                    except Exception:
                        tp_sp_group = None
                context_manager._sglang_tp_sp_group = tp_sp_group

    return transformer, transformer_2


def refresh_context_on_transformer(
    transformer: torch.nn.Module,
    num_inference_steps: int,
    scm_preset: str | None = None,
    verbose: bool = False,
) -> None:
    """Refresh cache-dit context for transformer."""
    steps_computation_mask = None
    if scm_preset is not None:
        steps_computation_mask = cache_dit.steps_mask(
            mask_policy=scm_preset, total_steps=num_inference_steps
        )
    cache_dit.refresh_context(
        transformer,
        cache_config=DBCacheConfig().reset(
            num_inference_steps=num_inference_steps,
            steps_computation_mask=steps_computation_mask,
            steps_computation_policy=scm_preset,
        ),
        verbose=verbose,
    )
    logger.debug(f"cache-dit refreshed on transformer (steps={num_inference_steps})")


def refresh_context_on_dual_transformer(
    transformer: torch.nn.Module,
    transformer_2: torch.nn.Module,
    num_high_noise_steps: int,
    num_low_noise_steps: int,
    scm_preset: str | None = None,
    verbose: bool = False,
    steps_computation_mask: Optional[List[int]] = None,
    steps_computation_mask_2: Optional[List[int]] = None,
    steps_computation_policy: str | None = None,
) -> None:
    """Refresh cache-dit context for dual transformers."""
    high_noise_steps_computation_mask = steps_computation_mask
    low_noise_steps_computation_mask = steps_computation_mask_2
    if high_noise_steps_computation_mask is None and scm_preset is not None:
        high_noise_steps_computation_mask = cache_dit.steps_mask(
            mask_policy=scm_preset, total_steps=num_high_noise_steps
        )
    if low_noise_steps_computation_mask is None and scm_preset is not None:
        low_noise_steps_computation_mask = cache_dit.steps_mask(
            mask_policy=scm_preset, total_steps=num_low_noise_steps
        )
    policy = (
        steps_computation_policy if steps_computation_policy is not None else scm_preset
    )
    cache_dit.refresh_context(
        transformer,
        cache_config=DBCacheConfig().reset(
            num_inference_steps=num_high_noise_steps,
            steps_computation_mask=high_noise_steps_computation_mask,
            steps_computation_policy=policy,
        ),
        verbose=verbose,
    )
    cache_dit.refresh_context(
        transformer_2,
        cache_config=DBCacheConfig().reset(
            num_inference_steps=num_low_noise_steps,
            steps_computation_mask=low_noise_steps_computation_mask,
            steps_computation_policy=policy,
        ),
        verbose=verbose,
    )
    logger.debug(
        f"cache-dit refreshed on dual transformers (steps={num_high_noise_steps}, {num_low_noise_steps})"
    )