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drama: load the checkpoint with direct I/O in file order and build the codec on its own thread - #925

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plotarmordev wants to merge 48 commits into
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plotarmordev:perf/drama3-load
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plotarmordev wants to merge 48 commits into
ashhart:mainfrom
plotarmordev:perf/drama3-load

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What this changes

Checkpoint weights stream onto the GPU with direct I/O in file order through two pinned slots (part of #914;
stacked on #924, its own commits are the last two). The codec builds its weight image on its own thread while
the backbone loads.

This stack implements #914 and depends on #915 (allocation cap), #916 (direct-read fallback) and #917
(Module.holds), inherited through #920.

This inherits the stack's overlap with #844, including the recorded CUDA integration and CHANGELOG.md conflicts;
land #844 first, then rebase the stack.

Receipt

  • Environment, with the TensorFold commit, MLX or PyTorch version, machine and GPU, checkpoint and revision:
    • Code. Head 68aeb3e51dd2, on main c7137bb3. No MLX or PyTorch.
    • Builds and host tests. An NVIDIA GB10 build host on Ubuntu 24.04.4 LTS aarch64 (Linux 6.17), with Zig
      0.17.0, nvcc 13.0.88 and CUDA_VISIBLE_DEVICES empty.
    • GPU measurements. A GB10 (sm_121) host with CUDA 13 libraries (cuBLASLt 13.1.1). Checkpoint
      fishaudio/drama-3 at e0a9218a; reference sglang-omni ab095ef9.
    • Which build was measured. These commits built on TensorFold 1e76a70e. Here they are rebased onto
      c7137bb3 with comments made single-line and files split. Every Drama fatbin of this head is byte-identical to
      the measured series' at the same commit. The host Zig is token-identical apart from the file split, compared
      with std.zig.Ast.
  • Exactness, from tools/bench_concurrent.py --alone --serial or token_sha against "draft": false: n/a for
    tokens. The same bytes land in the same device buffers. The host tests compare the staged image with a
    loader-order copy, and the 46 normal replies stayed byte-identical through this stage (speed-stages.json).
    Fidelity against the reference is not qualified (qualification.json); preserving native output does
    not establish reference equivalence.
  • Decode speed before and after, from tools/bench_openai.py: n/a. Only loading changes, and decode is untouched.
  • Prompt speed before and after: the cold first request's ttft_s from tools/bench_cache.py --require-cold on a long prompt, or "n/a" with the reason when the change cannot reach prompt processing: Prompt processing
    was not measured; these commits change loading rather than the prompt kernels. The following numbers measure
    loading/startup, not cold-request TTFT (speed-stages.json):
    • 53.3 s before;
    • 6.2 s after stage 03, which is these two commits;
    • 6.4 s from process start to ready on the final build (before-after-02, one start, reused caches).
  • Tests run, with pass, fail and skip counts:
    • GPU audio gate on the stack's tip bef432bbb25e (one GB10, under the recipe's guard): all 46 normal-request
      audio bodies byte-identical to the promoted pre-upstream build, the long-05 clipped body identical in both
      passes, bench/stream_check.py 9/9, warm RTF 0.654 against the pre-speed 1.087, and all six tower one-row
      projections on drama_tower_gemv.
    • CUDA_VISIBLE_DEVICES= zig build test-cuda-host --summary all from an empty local cache: 29/29 steps, 496 passed, 0 failed, 0 skipped. This includes the stager's two new tests (read planning and landed bytes for random copies).
    • zig build native -Dnvcc=/usr/local/cuda/bin/nvcc --summary all: 46/46 steps.
    • zig build fatbins -Dnvcc=/usr/local/cuda/bin/nvcc: every Drama fatbin is byte-identical to the measured
      series' at this commit.
    • python3 tools/zig/lean_check.py: 527 problems at every commit, main's 527 (lean_new.py: 0 new).
    • zig fmt --check: clean at every commit.
  • Not run, and why:
    • A disk-cold load with the page cache dropped: the recorded loads reused caches.
    • A GPU run on this exact head: the GPU audio gate ran once, on the stack's tip bef432bbb25e; this head is
      host-tested only.
    • Metal: the family is CUDA-only.
    • tools/bench_openai.py, bench_concurrent.py and bench_cache.py: they drive text tokens, so speech used the
      recipe's harness.

Checklist

  • Every token still goes through the lane rounds. No serial path, and nothing that needs drafts off. (Drama 3
    generates audio frames in its own host loop, as in drama: Drama 3 (fishaudio/drama-3) text-to-speech on CUDA #920. Text families are unchanged.)
  • Drafted output equals "draft": false, a resumed prompt equals a fresh one, and concurrent equals solo. (No
    drafts or resume. The measured speed stages preserved the 46 normal corpus audio bodies; concurrent-equals-solo
    is not measured.)
  • No precision traded for speed. If the bits change, the description says which sums change and why. (No arithmetic changes.)
  • Prompt processing is no slower than the last release. (Not measured. Text prompt paths are not touched.)
  • The description says which platforms I ran, Metal M1 to M5 and CUDA, and which I could not.
  • New tests fail before the change, pass after it, and skip cleanly without their dependency. (The stager tests pass and need no GPU. They test new code, so there is no before.)
  • Comments and docstrings are one line. No measurements or history in the source.
  • No personal data, machine names, internal hosts or local paths. No AI attribution lines.

setAllocationLimit bounds the bytes of device buffers plus pinned host buffers. An allocation reserves its
bytes before the driver call and a failed call refunds them, so concurrent allocations cannot overshoot the cap
and a refused one leaves usage and the measured peak unchanged. Host counts now take the same lock as device
counts. An engine that admits a model against a memory budget can hold its own allocations to it.
The tower turns a backbone row into a frame's ten codebook values: four shared and nine residual layers whose
cache keeps every preceding text and audio row, a semantic head and the reference sampler (temperature, top-p over
the whole vocabulary, then top-k). Its projections run on cuBLASLt; drama_tower.cu holds the mixer, norms, RoPE,
attention and sampling kernels.
The codec decodes ten codebooks a frame to mono 44.1 kHz PCM, 2048 samples a frame, as the reference's FP16
vocoder does: RVQ, the windowed post-module transformer, two upsample stages and the DAC decoder. codec_pth.zig
reads torch.save's zip archive and runs its state-dict pickle on a VM that knows only the opcodes and globals a
tensor state dict uses, so nothing in the file runs. Weight norm is folded in FP32 and tensors are cast to FP16
with round-to-nearest-even, as the reference does.

codec.zig holds the decode; codec_load.zig holds the codec's geometry, the weight-norm folding, the FP16 casts
and the one device weight image.
An engine may now synthesize speech: SpeechRequest carries a prompt, sampling settings and caller-owned PCM,
Info.speech describes the audio it produces, and Info.text_generation lets a speech-only engine refuse the text
routes. Text submit gains error.Unsupported, which the chat route reports as a request error.
The native CUDA backend opens fish_omni checkpoints with the Drama 3 host: one synthesis at a time on a worker
thread that owns the context, stream, backbone, tower and codec, admitted against the same memory pool the text
families use. The pool reading moves to cuda_memory.readPool so both paths share it, and the host caps its own
allocations at what it was admitted for. Options the host cannot honor are refused at open.
OpenAI's speech request, built into Drama 3's default-voice prompt as the reference's prompt builder builds it
and synthesized whole, then sent as WAV or raw PCM. Fields the route would silently drop are refused, and a
speech-only engine starts the server without the text-only services.
Drivers that check the native backbone and tower against captured reference tensors, replay single operators
against them, and trace each stage for attribution, plus tf-cuda-test drama-conv and drama-qk on synthetic rows.
None of them runs as part of the host tests.
The codec can decode frames from a given frame onward at their absolute rows, reading the rows before them that
its causal convolutions and attention windows reach, and writing nothing before them. Every chunk boundary gives
the same samples as one decode of all frames, so audio can be decoded while it is generated.
Drivers that decode captured codes with the native codec for comparison with the reference decoder, replay its
RVQ and weight preparation in isolation, and trace each decoder stage. None of them runs as part of the host tests.
… generates

A streamed speech request now receives audio events: each one hands the caller a final, rising prefix of the PCM
before the finished event. The Drama host decodes the first frame alone, for the earliest audio, then frames in
groups, and publishes each decoded prefix.
…ve host and their tool steps

Embeds the backbone and tower fatbins, adds the drama module to the native server and its host tests, and a build
step per backbone and tower oracle, replay and trace driver. The codec's kernels and tools follow on their own.
… are decoded

With stream: true and response_format pcm, the route sends HTTP/1.1 chunks as the engine publishes audio. A stream
that fails after its first chunk ends without a terminator, so a client cannot mistake it for complete audio.
…memory

A single-row projection copies each warp's weight chunks into a shared ring with cp.async ahead of use and reads
them back with ldmatrix, issuing the same mma sequence on the same fragments in the same K order as the row
tiling it replaces, so the results are the same bits.
Embeds the codec fatbin and adds a build step per codec oracle, replay and trace driver. With this the series
builds.
Decodes the same frame codes whole and in the host's chunk policy, one frame at a time and in irregular chunks,
each over NaN-poisoned scratch, and requires every chunked decode to equal the whole decode.
Some file systems accept an O_DIRECT open and then fail the aligned read with EINVAL. The reader now clears
O_DIRECT on that descriptor and reads again through the page cache instead of failing the load; a test injects
the refusal.
A marker test: an image can carry a device global that promises something about its kernels, and the host can
check for it before relying on the promise. Any driver failure, a missing name included, answers false rather
than an error. A test drives it through a fake driver table.
Drama 3's backbone is a Qwen3.5-35B-A3B-style hybrid: 30 Gated DeltaNet and 10 gated full-attention layers,
each with a 256-expert top-8 block-FP8 MoE and a gated shared expert. Model.run appends rows and returns every
row's final-norm hidden state and the last row's semantic logits.

The kernels follow the arithmetic of the sglang-omni reference: the canonical 64-token chunked GDN prefill
(drama_gdn_chunk.cuh, after flash-linear-attention's kernels as SGLang carries them), the packed recurrent decode,
gated attention with Q/K norm and partial NeoX RoPE, dynamic 1 x 128 FP8 activation quantization, and the BF16
tensor-core GEMMs in drama_backbone_gemm.cu. Weights load as stored; nothing is requantized.

THIRD_PARTY_NOTICES.md credits flash-linear-attention (MIT), whose chunked kernels the GDN prefill is adapted from
and whose packed decode the recurrence follows.
…ync ring

The one-row path keeps the same mma sequence and fragments as the tilings it replaces, now for the semantic
head's grouping too, while its weights stream through an unpadded shared ring whose 16-byte pieces are swizzled
so each read still hits distinct banks.
…ation

The residual add and RMS norm before the MoE also write the normed rows' FP8 groups, in the same order and
rounding as the separate quantization launch they replace.
The routed rows are stored as their FP8 quantization and the shared expert's rows as BF16, in one launch instead
of two, with the same arithmetic per row.
Each thread of drama_moe_combine now writes 8 contiguous outputs from 16-byte loads; every sum keeps its order.
A warp loads and scores its keys in batches with the next batch's loads issued early; the running softmax update
stays in key order, so the result is unchanged.
A cluster of CTAs shares a head: each scores its share of the key tiles, all gather the scores over distributed
shared memory and replay the tile updates in order, then each sums its own slice of the head. Every value is
computed as the one-CTA kernel computes it; prompt rows keep that kernel.
… order

stager.zig collects each tensor's copy as the loaders walk their names, sorts them by file offset and streams
each file through two pinned slots, reading one with O_DIRECT while copying from the other, in pieces that never
span two device allocations.
…udio

A synthesis that reaches max_frames without an end of speech keeps the audio of those frames, as the reference
returns its capped replies, instead of failing without audio. A whole reply carries X-Finish-Reason stop or length;
a stream declares the trailer and ends with X-Finish-Reason: length only when it was clipped.
…ame launch

For a single row, the attention launch also does drama_attn_prep's norm, RoPE and cache append, taking the new
key and value from registers, with the same roundings as the separate launch.
The sampler's ranking comes from a stable LSD radix sort under the same strict total order the bitonic network
used, so the permutation and every sum over it are unchanged.
…one loads

The codec's host-side weight image is CPU work that the backbone and tower reads leave room for; it now runs on
its own thread with the context current there, and the host joins it before it finishes opening.
@ashhart

ashhart commented Oct 17, 2026

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Thank you, @plotarmordev, we will carry the direct/parallel loading work with your credit into the combined Drama owner and loader; the landing order and remaining checks are in our reply on #927.

Posted by Ash's AI Assistant Synthena

Conflicts, each kept from both sides:
- zig/build/cuda.zig: family() returns radio and drama; engines() and
  nativeServer() take core, heat and drama; main's tf-cuda-test runner,
  kernel contract and GLM/LFM2/RADIO helpers stay ahead of the drama tool steps.
- zig/src/core/engine_api.zig: the speech types beside main's vision types;
  SubmitError holds Unsupported and Stale; the VTable keeps submit_speech
  beside recall, imprint and drain.
- zig/src/native/cuda.zig: families lists lfm2_vl then fish_omni; pool() and
  weightBytes() leave for cuda_memory's readPool() and weightBytes(); openDrama
  refuses main's new --vision, --precision, --record and --learn-conversations.
- zig/src/server/{chat,root,routes}.zig, zig/tests/cuda/main.zig: both sides'
  error arms, imports and test files.
- zig/src/server/speech.zig: imports the named json module (ashhart#860).
…treaming

CHANGELOG.md: the streaming line stays under ## Unreleased, above main's ## 1.0.12.
…ts image holds no cluster kernel

drama_attention_decode's __cluster_dims__ and cluster group exist from sm_90 on, so nvcc refused
drama_tower.cu for sm_80, sm_86 and sm_89, and the backbone admits sm_89. The kernel now compiles
for sm_90+ images only, and the tower resolves and launches it only when the device has clusters;
other devices run the one-CTA drama_attention the multi-row calls use. The sm_120 and sm_121
images are byte-identical.
…n types in their own files, Drama's refusals in cuda_refusal

Upstream main's engine_api.zig is at 600 lines and native/cuda.zig at 583, so the merge took them to
632 and 602. The speech request, result, offer and submit error move to core/speech_api.zig, and
the image and video input types to core/vision_api.zig, re-exported under their names as
rows_ask.zig's are. Drama 3's flag refusals join LFM2's in cuda_refusal.zig, with a test. No
declaration, behavior or test is removed.
…ion types in their own files

zig/src/core/engine_api.zig: the speech types leave as on 920; the streamed request's comment and stream field move with them into core/speech_api.zig.
ashhart#921 adds Event.audio; main's newer lane host tests switch over every event, so zig build test stopped compiling them.
@ashhart

ashhart commented Oct 18, 2026

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Thank you, @plotarmordev, for the speech protocol and infrastructure, and @drowzeys for the family, backends and codec. The selected work from #925 is included through #927 (5dcf77d7c), the consolidated Drama 3 landing in 1.1.0. One CUDA/Metal family uses bounded shared frame rounds, request-owned state, native checkpoint/codec loading and streamed PCM speech. HTTP retains its checked default-voice subset. Full scope and audio, interleaving and completion results are on #927: Apple M5 Ultra norm checks passed 1/1 and CUDA resources passed; checkpoint audio fidelity, seeded concurrency and cancellation remain unrun.

Posted by Ash's AI Assistant Synthena

@ashhart

ashhart commented Oct 18, 2026

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The consolidated Drama contribution shipped in 1.1.0 as 5dcf77d7c; thanks @plotarmordev and @drowzeys. Experimental attention variants remain separate. We're closing it as landed.

Posted by Ash's AI Assistant Synthena

@ashhart ashhart closed this Oct 18, 2026
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