- base_precision="mxfp8": torchao MX block-scaled float8 compute on the frozen
base linears (Blackwell sm100+, cuBLAS kernels). Applied after add_adapter like
fp8, never fatal, weights stay bf16 in memory. Measured 1.16x over compiled
bf16 on Z-Image at 1024px batch 4 (16k tokens/step); a wash at small token
counts, so it stays an explicit opt-in and auto never picks it.
- SDXL: regionally compile the U-Net's BasicTransformerBlocks through the same
never-fatal wrapper the DiT trainer uses. 1.35x steady state at 1024px batch 4
with same-seed loss parity (~1e-5 per step) and unchanged peak VRAM; ~30 s
one-time warmup. Steady-state samples/sec now excludes step 1, matching the
DiT trainer.
- /info: mxfp8 advertised only on sm100+; supports_compile now true for sdxl.
- NVFP4 training: not available in torchao 0.16 (no autograd path, no training
recipe), so NVFP4 stays an inference-only quant for now.
193 diffusion backend tests green; frontend build clean.
Fuses the block's two inline modulations (1 + scale) * norm(x) + shift and two
gated residuals x + gate * out to torch.addcmul, matching the existing qwen /
z-image / flux fusions (compile-safe, 1-ULP more accurate, body-drift guarded).
Stock-vs-patched equivalence test included; install count is now 7.
Inference:
- krea-2 DiffusionFamily (Krea2Pipeline / Krea2Transformer2DModel, base
krea/Krea-2-Turbo, bf16 only, no GGUF/sd.cpp mapping yet)
- Per-component pipeline loader (core/inference/diffusion_krea2.py): the krea
repo is exported with transformers 5.2, so the tokenizer config
(extra_special_tokens as a list, no slow-tokenizer vocab files) and the
text encoder rope settings (rope_parameters vs rope_scaling) need explicit
compat on the 4.x line; values are copied verbatim and equal the 4.x
Qwen3-VL defaults, so the math is unchanged. from_pretrained also
type-checks the tokenizer against the declared slow class, so the pipeline
is assembled through its constructor with the model_index init config
(is_distilled carries Turbo's fixed mu=1.15 schedule)
- Trust allowlist entry, curated picker entry + 8 step / cfg 0 defaults,
int8 exclusion token for the M=1 Krea2TimestepEmbedding projection
Training:
- krea-2 _FamilySpec in the DiT trainer: phased conditioning/transformer
load through the compat loader, shared Qwen-Image VAE latent path,
fixed-512 text embeds (static shapes, plain concat collate), inline 2x2
latent packing + shared position grid, the authors' recommended LoRA
target set and rank/alpha 32, lr 3e-4, 512px presets
- GPU smokes on B200: nf4 2.9 steps/s at 11.5 GB, bf16 3.4 steps/s at
30.1 GB, bf16 + regional compile 5.2 steps/s; adapter round-trip
generation verified
- num_epochs on the diffusion train request and config: > 0 overrides
train_steps with epochs x ceil(N / (batch x grad_accum)) optimizer steps,
resolved against the dataset size in both the DiT and SDXL trainers
- Train settings: run length control with a Steps / Epochs unit select
- Stop dialog: flex-wrap footer so Stop and save wraps instead of clipping
out of frame at narrow window widths
New base_precision config for the DiT trainers: nf4 (unchanged default) |
bf16 | int8 | fp8 | auto, advertised per family + per machine through
/api/train/diffusion/info (precision_modes, recommended_precision,
supports_compile) so the UI can gate the selector.
- bf16: dense transformer + regional torch.compile (auto-armed). The
measured speed mode: 2.3x nf4 on FLUX (1.81 -> 4.12 steps/s), 2.6x on
Z-Image (2.5 -> 6.38 steps/s) on B200, at dense-weight VRAM
(FLUX 24.7 GB / Z-Image 13.6 GB peak vs 10.4 / 4.7 for nf4).
- int8: torchao weight-only int8 on the frozen base, quantized AFTER
add_adapter (quantizing first trips peft 0.18's TorchaoLoraLinear,
which is incompatible with the torchao 0.16 config API). Runs eager:
inductor rejects the int8 subclass training graph (aliased subclass
outputs), so compile is force-disabled for it.
- fp8: torchao convert_to_float8_training on the frozen linears
(filter skips lora_ modules, proj_out, non-divisible-by-16 dims,
pad_inner_dim), applied after add_adapter, compile auto-armed.
Works and round-trips, but measured SLOWER than compiled bf16 at
LoRA-training shapes (FLUX 3.15 vs 4.12 steps/s; Z-Image similar),
so it is an explicit opt-in and auto never picks it.
- auto: free VRAM (measured before load) + dense-size table -> bf16
when it fits with headroom, int8 in the middle band, else nf4.
Prequant bnb repos always resolve to nf4; dense modes on them are
rejected at validation with a pointer to the family's dense base.
Two crashes found and fixed along the way:
- The cuDNN SDPA backend's training graph fails on the FLUX attention
shapes (torch 2.10 + cu130, B200): mha_graph.execute errors, then the
context degrades into illegal memory accesses. The perf-flag guard now
pins flash/mem-efficient SDPA for the run (mathematically equivalent,
snapshot/restored). nf4 escaped it by routing attention differently.
- Regional compile now uses dynamic=True (the inference layer's proven
default): dynamic=False specialisation fused a gemm_and_bias epilogue
that failed with CUBLAS_STATUS_EXECUTION_FAILED on the FLUX training
graph; dynamic=True is also faster (Z-Image 3.84 -> 6.38 steps/s).
Verified: 98 backend tests green (new test_diffusion_base_precision.py:
validation, auto policy table, fp8 filter, compile gating, /info fields);
per-mode 40-step runs on FLUX + Z-Image with loss means inside the nf4
envelope and adapter round-trip generation through the normal LoRA path
for bf16-, fp8-, and int8-trained adapters.
Perf core for the diffusion trainers, defaults preserving the training math:
- Phased model loading: the pipeline now loads without its transformer
(conditioning only), captions are encoded and the text encoders freed,
the VAE latent cache is built and the VAE freed, and only then does the
transformer load. The multi-GB denoiser never shares VRAM with the
encoders, cutting measured peak VRAM on B200: FLUX 17.1 -> 10.4 GB,
Qwen-Image 19.1 -> 12.8 GB, Z-Image 7.3 -> 4.7 GB.
- Latent cache (cache_latents, default on): per-image crop/flip variants
(cache_variants, default 4 vs the single frozen variant of the diffusers
--cache_latents) store the VAE posterior's affine parameters, so every
step still draws a fresh VAE sample; a cached center-crop Z-Image run
matches the uncached one at the bf16 nondeterminism floor.
- True batching: train_batch_size now actually batches the transformer
forward (it was silently 1). nf4 dequant dominates the step cost, so
batch 4 lands near batch-1 step time: 4.0x samples/s on Qwen-Image,
3.1x on FLUX, 2.1x on Z-Image, with multi-seed loss envelopes
overlapping batch-1.
- LR scheduler support in the DiT loop (lr_scheduler / lr_warmup_steps
were accepted but ignored); progress events now report the real
per-step LR.
- TF32 + high fp32 matmul precision under enable_tf32 (default on),
snapshot/restored around the run. cudnn.benchmark is scoped to a
caller opt-in only: autotuning the fp32 VAE convs doubled peak VRAM
on the DiT families for zero steady-state gain.
- Vectorized sigma gathering (drops a per-step Python search loop),
cached FLUX img_ids/guidance, fused torch AdamW fallback, steady-state
samples_per_second (excludes the first-step warmup).
- Regional torch.compile plumbing (compile_transformer off/on/auto with
eager fallback): auto stays off over a bitsandbytes base where compile
is a net loss (27 s warmup, slightly slower steady on Z-Image); it
arms automatically for the dense/quantized speed modes that follow.
- Stop parity with the LLM trainer: /api/train/diffusion/stop accepts an
optional {save} body and the service forwards save=False as a
no-save cancel; a new preparing event surfaces cache-build progress.
- SDXL trainer gets the same latent cache, perf flags, and fused
fallback; its batching, LR schedule, and min-SNR stay as they were.
Verified: 83 backend tests green; per-family 30-40 step runs with
adapter round-trip generation through the normal LoRA path (FLUX,
Qwen-Image, Z-Image all pass).
The base-model select's state could briefly hold the previous family's
repo after a family switch (the reseed effect runs a beat later, and a
value with no matching option makes the browser display the first option
anyway). The request then carried the stale repo: picking Qwen or Z-Image
still sent black-forest-labs/FLUX.1-dev and surfaced FLUX's gated-repo
error under the wrong family. Derive an effectiveBase clamped to the
current family's repos and use it for the select value, the start
request, and the deploy fallback.
Also move the Trigger prompt above Adapter name: the trigger describes
the dataset, the name only labels the output.
Add an Examples group to the training-images dropdown that imports a
curated dataset in one pick, alongside the existing cards. Cards now show
up to three preview thumbnails pulled from the public HF datasets-server
so the set is visible before download. Hide the trigger prompt when every
image already has a caption (a captioned style set needs no trigger), and
turn the training-settings toggle into a ghost button with a rotating
chevron.
Large example datasets (100+ images) rendered every tile at once, so the
caption review grid grew unbounded. Show 24 images per page with < >
chevrons and an x-y of N indicator; a new dataset or refresh resets to
the first page.
Two permissive ~100-image sets for the Train tab: huggan/smithsonian_butterflies_subset
(CC0, the classic diffusers-docs training set, imported as a subject set with a trigger
prompt since its metadata columns are species names not captions) and m1guelpf/nouns
(CC0, captioned pixel-art avatars via the text column). Both cap at 100 images.
The example-dataset cards still overran the ~340px config column: the
license used the Badge component whose baked-in w-fit and whitespace-nowrap
ignored the max-width and truncate, and the grid children had the default
min-width auto so wide content pushed past the column edge and clipped the
Import buttons. Replace the badge with a plain truncating pill span, and
give the config column min-w-0 with overflow-x-hidden so nothing escapes
its width.
When a dataset with images is selected, show a strip of up to 8 sampled
thumbnails with a +N more tile, so users can see what is in the folder
before training. Clicking the strip opens the existing caption review
grid. Samples are drawn evenly across the folder and refresh on dataset
change or after an upload/import.
The Train tab reused the LLM charts section, which also rendered an empty
Grad Norm card and an Eval Loss card showing an Evaluation not configured
placeholder with a red smear. Neither applies to diffusion LoRA training.
Add a diffusion-only two-card view that reuses the loss and learning-rate
cards directly with fixed presentation defaults, and note under the loss
chart that per-step loss is noisy by design so users read the smoothed
line for the trend rather than the raw jitter.
The example-dataset cards used a two-column grid in the ~340px config
column, which wrapped titles one word per line and let the long license
text overrun into the neighbouring card. Switch to one card per row with a
horizontal layout: title with a compact truncated license badge (full text
in the tooltip), a two-line clamped description, and the Import button on
the right.
The Create/Train switch had an icon inside the Train trigger that overhung
the pill corner. Drop the icon, make both triggers a fixed equal width so
the active pill sits flush in the top bar.
The fp32 LoRA parameters and the bnb 4-bit base matmuls need a single
compute dtype during the forward, exactly like the diffusers dreambooth
scripts run under accelerator.autocast. Without it the 4-bit backward on
FLUX.1-dev fails with an illegal-address CUBLAS error partway into the
first step. Z-Image and Qwen-Image smokes are unaffected and the SDXL
path (its own trainer) is untouched.
Replaces the Train LoRA dialog with a top-bar Create | Train segmented control next to
the model selector. Create renders the existing generation workspace unchanged; Train
renders the full-page training panel (unmounted in Create so its polling stops while the
backend run and its retained metric history survive a tab switch). Adds a deploy handler:
loading the trained adapter's base as a pipeline, queueing the adapter so the LoRA
discovery effect applies it once the base is loaded and LoRA-capable for the matching
family (with a mismatch warning), seeding the prompt with the trigger, and switching back
to Create. Removes the now-unused dialog.
New full-page training workspace for the Images tab. Left column configures the run:
model family (FLUX.1-dev, Qwen-Image, Z-Image, SDXL in popularity order, with per-family
VRAM/license notes and defaults, backfilled from the backend families list when present),
base repo, dataset (existing folder, browser upload, or one-click example import), an
in-browser caption labeling grid (per-image thumbnail + caption saved on blur, delete,
uncaptioned highlight), adapter name, trigger prompt, and collapsed training settings.
Right column shows the live run: progress + loss/avg/speed/peak-VRAM readouts, the reused
training loss/LR charts fed from metric_history, and a completion card that deploys the
adapter into Create or starts another run.
Extends the Images training client for the Train tab: the status type now carries
metric_history (step/loss/lr) plus catalog_path/family/base_model/samples_per_second/
peak_memory_gb; the start request gains model_family; and info gains an optional
families list (per-family bases + defaults). Adds typed calls for the dataset
labeling and one-click example endpoints: list images with captions, thumbnail URL,
write/clear a caption, delete an image, list example datasets, and import an example.
Cover the DiT spec table, the QLoRA prequant heuristic, the Z-Image bf16-only
guard, the gated-repo name check, family resolution now that FLUX/Qwen/Z-Image
are trainable (and GGUF repos are rejected as inference-only), the families list
in /diffusion/info, and the gated-base 400 preflight that leaves the GPU
untouched.
The training info endpoint now returns the trainable model families (name,
label, default + allowed base repos, recommended defaults, and a VRAM/access
note) so the Train UI can offer a base picker with realistic guidance. The start
route preflights a gated base repo (HEAD model_index.json with the user's token)
BEFORE freeing resident GPU workloads, so a missing FLUX.1-dev license/token
fails fast with an actionable 400 instead of evicting the loaded model and then
hitting a confusing mid-load 401.
SDXL re-encoded every caption with both CLIP text encoders on every step (pure
waste, since captions are constant) and kept the encoders resident. Precompute
each unique caption's embeddings once, then free the text encoders before the
loop: numerically identical (embeddings are deterministic and this consumes no
torch RNG, so the noise/timestep stream is unchanged) but faster and ~1.5 GB
lighter. Default the optimizer to 8-bit AdamW (bitsandbytes) with an fp32
fallback, halving optimizer state with no meaningful LoRA quality cost. Env
toggles (UNSLOTH_DIFFUSION_NO_PRECOMPUTE / _FP32_OPTIM) let the accuracy guard
A/B the paths.
