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qwen3_5 cuda: 2, 3, 5 and 6-bit tiles of their own width and a prompt GEMM for them (27B oQ2 on 16 GB) - #859
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- zig/src/platform: `sys`, imported by every module (zig/build/sys.zig wires it). On POSIX it is std.c, std.posix and std.DynLib unchanged; on Windows win_c.zig gives libc's surface over the UCRT and Win32 (integer descriptors, directory descriptors, readdir, pread/pwrite, high-resolution sleep, monotonic clock, /tmp and /proc/self/exe mapped), win_posix.zig the server's sockets over Winsock, console events as SIGINT/SIGTERM, and LoadLibraryW for DynLib. - std.c and std.DynLib calls go through `platform` (mechanical). - build.zig routes Windows targets to the CUDA build. - Server: socket closes and writes are explicit, the key file's mode check is skipped on NTFS (ACLs), descriptor limits are a no-op. - shard_edit: the shard's map is released before the rename, since Windows refuses to replace a mapped file. - Tests that need symlink privilege or mode bits skip on Windows. zig build test-cuda-host passes on x86_64-windows.
- Kernel fatbins build with nvcc and cl.exe: MSVC's conforming preprocessor is passed on Windows hosts (CUDA 13's headers need it), and explicit kernel instantiations carry the __restrict__ qualifiers their templates have (MSVC counts them in the function type; the generated code is unchanged). - Nemotron's checkpoint source keeps io_uring to Linux; elsewhere its existing thread reads run. - pull_exlr8 raises no descriptor limit on Windows. - modelopt test: the lane's slice partials are allocated. GPUs without clusters (before sm_90) reduce split K through them; the test passed none, so it wrote through a null pointer on Ampere and Ada. zig build native and install build with -Dnvcc=... -Dsm=89, and tf-cuda-test's synthetic suites pass on an RTX 4090.
- pull: where Windows refuses the snapshot's symlink, the snapshot path
becomes a hard link to its blob (CreateHardLinkW through `sys.c.link`):
no extra space, and learning already refuses linked shards. Link
failures are logged with their reason.
- HOME falls back to USERPROFILE (Windows sets no HOME) for the hub cache
and every libc getenv("HOME").
- Tests read optional fixture variables through `platform.getenv`;
std.process.Environ.getPosix does not build on Windows.
- The learned-state symlink tests skip on Windows (symlinks need
privilege); `sys.c.symlink` asks for an unprivileged one.
zig build test passes on x86_64-windows.
- docs/WINDOWS.md: requirements, build, run, how the port works and how it differs from Linux; the README points to it. - -Dstrip reaches tensorfold-native before its install step is made, so the step no longer expects a .pdb the stripped build does not write. - zig fmt on the platform files.
8080 and 8000 are taken by too many other servers; serve listens on 8888 unless --port says otherwise, and the docs and bench scripts follow.
The MLX affine 4-bit checkpoint on the native CUDA server, beside Nemotron: qwen35.cu holds the Metal engine's glue at its bf16 rounding points (gated delta rule, causal convolution, gated attention), cuda.qlinear's affine-4 kernels do the projections, sample.cu draws on the device. Windows of up to 16 rows record each row's recurrence and convolution tail, so the lane core shares rounds across streams and keeps partial copies; a window's rows equal one-row steps bit for bit. draw.zig is the host draw both backends now share. On an RTX 4090: 210 tok/s for one stream, 1250 tok/s across eight; logits agree with an fp32 reference at every position of a 36-token check.
…mory The 2B's CUDA engine now reads its widths from config.json (cuda_geometry.zig): linear value heads over fewer key heads, more query heads a key/value head, an untied head, an A_log stored as bf16. The 27B's logits agree with an fp32 reference at every position of a 36-token check, and its windows equal one-row steps bit for bit; the 2B's output is unchanged. Two Windows driver costs shaped the rest. Each kernel launch grew with the process's allocation count (1.2 ms a launch over 1,900 weight buffers), so a model's weights and scratch now live in one arena (cuda_weights.zig packs each projection through a reused staging buffer: the 27B loads in 25 s, not 200). And a process's first forwards through a buffer stall for seconds, so the engine warms every request path at load and the backend keeps a pool of stream caches that `reserve` allocates and runs a row through once the server knows its stream count. On an RTX 4090: the 27B decodes at 37 tok/s in the runner, 31 to 35 tok/s served, 210 tok/s across eight streams; the 2B stays at 210 and 1,250.
A forward's launches (the embedding to the kept rows' logits) are captured the first time a shape (rows, windows, recording) is seen and replayed after; the attention chunk count moves into the per-forward table so a graph stays valid as caches grow. Prompt chunks stay uncaptured: their GEMMs dwarf the launches, and each length would be a graph of its own. A new graph's first run pays the Windows driver's stall (about a second on a wide model), so `reserve` also captures the shared rounds' shapes, a row of each of 1 to n streams, at load. Bit for bit the same logits; on an RTX 4090 the 2B steps in 2.8 ms instead of 5.3 (served: 324 tok/s, 1,560 across eight streams) and the 27B in 23.8 ms instead of 26.9 (served: 40 tok/s, 243 across eight).
--drafter loads z-lab's DFlash2 draft model behind the lane core's Drafted wrapper: the target writes each row's residual after the drafter's five tapped layers into a ring a stream, the drafter folds those rows into a context of keys and values, and after every verify it drafts a block of seven tokens past the pending one (the target's own embedding and head at its ends, a codebook selector tracing one path through each row's best sixteen). Its projections are quantized to affine-4 on the host at load and run through the target's kernels; its glue is qwen35_draft.cu. The Windows driver stalls a buffer's first kernel and a new graph's first run for seconds, so the drafter pools its contexts and a captured forward now serves every verify shape: its launches cover a bucket of rows and every window, and the kernels read the true counts from the device. On an RTX 4090 the 27B serves 52 to 58 tok/s greedy with drafts against 40 plain, about 100 tok/s on long replies, the same tokens either way; plain decoding keeps its 24 ms step. The 2B is unchanged.
A verify window's rows may form a tree (each row's parent given): the convolution taps, the delta rule and attention follow each row's own branch, and the DFlash2 drafter fills the lane core's planned lanes (each lane its parent's rank-r choice by the codebook selector), so a lone stream verifies up to 12 lanes a round and the planner learns which shapes land. A verify no longer snapshots every row's state (1.3 GB shared, which capped the 27B at 8 rows): each stream logs its rows' decay, write and key, and keep replays the kept path onto the recurrence in one pass (and moves a tree's kept keys down), so any window width fits. One-row steps and prompts update in place as before. The lane host times the target's windows at load, which the depth rule had lacked (it had been capping chains at 3 drafts). The runner's new tree mode verifies tree windows with junk branches against step logits (bit-exact on both models).
What the port serves beyond Nemotron: Qwen3.5-2B and Qwen3.8-27B with its DFlash2 drafter, the speeds measured on an RTX 4090, the load time and why, the timing and chain-only switches, and what is not there.
The lean rule (tools/zig/lean_check.py) counts a comment that runs on to a second line; the Windows port's new files had a hundred such runs. Each is one line of at most 120 columns now, and the checker reports the same 539 problems as main.
direct_io opened files with O_DIRECT on Linux alone. On Windows the same open now asks for FILE_FLAG_NO_BUFFERING (which win_c maps O_DIRECT to), and the 4 KiB-aligned spans it already reads satisfy the sector alignment that needs; a file system that refuses it still falls back to buffered reads. The direct-read test runs on Windows too, checking the executable's bytes against buffered reads of it.
SIG.IGN is a function pointer made from 1, as std.posix has it. aarch64 requires function pointers to be aligned unless the type says align(1), so the cross-build for aarch64-windows refused it. With align(1), as std's own handler type has, tensorfold-native cross-compiles for aarch64-windows with the GB10 (sm_121) fatbins; no hardware has run it.
The Windows page opens with what the build is, what it is tested on and that it cross-compiles for aarch64-windows; the README's model table and the CUDA paragraph say Windows where they said unofficial port.
The no-GPU workflow runs zig build test on windows-latest beside ubuntu-latest, so the platform layer is built and tested on every pull request.
Every other module calls libc through `sys`; the drafter's four getenv calls were the last direct std.c calls in a file the Windows build compiles.
After a prompt the lane core hands the drafter every prompt row's features; the CUDA backend refused any request wider than its tap ring (2,176 rows), so a 27B request with --drafter and a prompt past that ended with RowsNotHeld, where the same prompt without the drafter ran. The ring keeps the newest tap_rows rows, which hold the drafter's whole context window, and absorb already reads only that window of what it is handed; the backend now refuses only rows not yet written or all gone. On an RTX 4090 the 27B with its drafter takes a 6,041-token prompt in 7.4 s, and its reply equals the one with "draft": false.
… attention cuts chunks at logical positions - rowanc held a window's rows as bits of a u32, but prompt chunks run up to 128 rows: rows from 32 on rotated at the wrong positions and attended the wrong keys. A chain row (no parents) now carries its index in its window under the top bit; tree windows (at most 16 rows) keep their bits. - tf_q35_attn_partial cut its 128-key chunks at a key's cache row, so a kept tree path whose window crossed a chunk boundary summed in other chunks than one-row steps and changed bits. Chunks are now cut at the key's logical position (the stream's length plus the ancestors before it). Checked on an RTX 5090 (Linux, sm_120), tf-qwen35-cuda over 300 ids on Qwen3.5-2B and Qwen3.8-27B: step bits unchanged, window and tree equal step byte for byte (tree differed from row 126 on the 2B and 254 on the 27B before). Prompt mode's last row against step's at 16 to 300 ids: KL at most 0.003 and the same argmax in 20 of 20 (before: 27B at 40 ids KL 2.3 with a different argmax, at 128 ids KL 1.35).
zig build test-golden and zig build fuzz-cortheon exist on every non-macOS host since the golden step moved into zig/build/golden.zig, so the golden check compiles against the platform layer on Windows: - the platform's posix gains sockaddr.in, timeval, connect and kill for a child's handle (TerminateProcess; HUP has no equivalent), setsockopt turns a timeval for SO_RCVTIMEO or SO_SNDTIMEO into Winsock's milliseconds, and a socket read that times out is WouldBlock, as std.posix reports it. - the check carries SystemRoot into the spawned server's environment, which Winsock needs to start, and drains the server's stdout after the port line on every host: the fake server logs each request there, and a full pipe (4 KiB on Windows) blocked it after sixteen cases. - on Windows the check cannot send SIGTERM or SIGHUP, so the sigterm-exit-0 outcome and the cases after a key rewrite are skipped and printed as such. On Windows the goldens give 306 of 315 equal with the same nine known differences as Linux, and the fuzz step passes its eight tests; the no-GPU workflow's Windows job runs both.
The loader tried only libcublasLt.so.13 and libcublasLt.so, so the cublaslt suite of tf-cuda-test reported LibraryUnavailable on Windows; there it opens cublasLt64_13.dll from the toolkit's bin folder.
The platform handed O_APPEND to the C runtime as _O_APPEND, whose write seeks to the end and then writes, so two threads appending at once could overwrite each other's bytes: the request log lost lines under concurrent requests, which the server goldens' request-log case caught on a slow runner. A descriptor opened with O_APPEND now writes through WriteFile at the end-of-file offset, which the kernel places whole, as POSIX does; the file keeps its write access, so ftruncate on such a descriptor still works (prompt_imprint repairs a torn index that way). A request_log test appends 200 lines from each of 8 threads and expects every line whole; it lost lines on Windows before this change.
The lifecycle/request-log outcome said only that the lines differ; it now gives both logs' line counts and the first line that differs, cut to 100 bytes each, so a mismatch seen on a CI runner can be read from its log.
A checkout with core.autocrlf, as GitHub's Windows runners make, gives the frozen request log CRLF line endings while the server writes LF, so the lifecycle/request-log case differed at its first line's end on windows-latest and nowhere else. Both logs compare with CRLF read as LF; the other goldens are parsed as JSON and never saw the endings.
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Ran this on Linux with an RTX 5090 (sm_120). That covers the "Linux" and "DFlash2 drafter with this target" items in Not run. First, a CI fix. Setup:
Served,
Without a drafter, the 27B oQ2, one stream,
Long context:
So the oQ2 runs with its drafter at 256K on a 32 GB card. Its prompt pass is slow there: 22 minutes, about 194 tok/s. That fits the Limits note that widths other than 4 have no prompt GEMM. The oQ2 answered with a sentence at 64K and 256K rather than "the code only", but it named the right code each time. Decode speed over 64-token replies at these lengths was too noisy to report. Not run: reply quality or perplexity on this card, an MLX or PyTorch oracle for the 27B, GB10. These speeds come from one card and aren't a comparison against the 4080 SUPER's. |
Test run on a GB10 (sm_121, aarch64 Linux)Head Setup. One DGX Spark: NVIDIA GB10 (sm_121, aarch64, 128 GB unified memory), Ubuntu kernel 7.0.0-1019-nvidia, driver 580.178.04,
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…'s widest stream The chunk width came from the longest stream or window in the forward, so a 201-key row cut its keys into 128-key chunks alone and 256-key chunks beside a stream past 8192, and a window crossing 8192 recut its earlier rows; either changed the fp32 sums. Each row now takes chunk_keys(its logical keys), the width its one-row step uses, in both the partial and the merge kernels, and the partials sit at a fixed max_chunks stride. tf-qwen35-cuda takes TF_Q35_PREFILL=N (start after N cycled ids) and TF_Q35_BESIDE=N (step an N-token stream in each forward), which cover both cases: before this change, windows from 8151 keys kept 36 of 120 rows and trees 35, and a 151-key stream beside one from 8189 kept 4 to 11 of 120; after it all of them equal one-row steps on the 2B and 27B.
…fits its selector rank The integer reader accepted zero, so a conv_group_size or num_key_value_heads of 0 reached a remainder at admission; sizes and divisors are now positive (mask_token_id alone may be 0). The host staging area held 16 rows at rank 256, so a larger selector_rank overran it; it is now sized for the admitted rank. Config.parse takes the bytes, so a host test covers both.
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Each module loads at the width the config's quantization table names it. Codes of 2 to 4 bits pack onto the affine-4 tiles and codes of 5 to 8 bits onto new 8-bit tiles, every code keeping its value, scale and bias, so nothing is rounded. affine8.cu's lane GEMV is lane_gemv's arithmetic a byte wide (each byte exact in bf16), with its split-K form; an odd-width embedding is widened at load and 8-bit rows have their own embed kernel. A uniform 4-bit checkpoint takes the same packs and kernels as before: the 2B's step, window, tree and prompt logits are byte-equal to the previous build's. The rope config's older "type" key is read as "rope_type" (mlx-community's OptiQ conversions write it). Checked on an RTX 4080 SUPER (sm_89): - tf-cuda-test affine8: 24 cases over 2, 3, 4, 5, 6 and 8 bits; tiles equal the host-widened codes' tiles, 8-bit products within 0.32 of the float64 bound, 1/3/9/16-row calls and split-K byte-equal. - A 2B requantized at 2, 3, 5, 6 and 8 bits (and a 6-bit embedding) gives the same logits as the same codes stored widened, in step, window, tree and prompt modes. - Qwen3.5-4B-OptiQ-4bit and Qwen3.5-9B-OptiQ-4bit: window and tree equal step over 300 ids; bench_concurrent --alone --serial at 1 and 4 streams all equal; about 130 and 78 tokens/s for one request. 8-bit modules have no prompt GEMM yet; prompt chunks run them on the decode tiles, 16 rows at a time.
The mixed-width loader widened 2 and 3-bit codes onto the 4-bit tiles and 5 and 6-bit codes onto the 8-bit ones, so a mostly 2-bit checkpoint took the 4-bit checkpoint's memory. affine8.cu's lane GEMV is now templated on the width: a lane's 16 code pairs a group sit in `bits` words, first codes in the low halves and second in the high, and bf16 (0x4300 | c) - 128 rebuilds each code exactly. The MMAs see the operands the 8-bit tiles give them, so a code's products do not depend on the width it is stored at. - AffineN (was Affine8) carries its width; AffineNKernels resolves a gemv and a split-K kernel for 2, 3, 5, 6 and 8 bits, and tf_affinen_pack packs them. - 4-bit modules keep the affine-4 tiles and prompt GEMM; uniform 4-bit checkpoints are unchanged. Embeddings still widen to 4 or 8 bits (rowBits). - TensorFold/Qwen3.8-27B-oQ2 takes 10.3 GiB and fits a 16 GB card. Checks on an RTX 4080 SUPER: - tf-cuda-test affine8: 24 cases; 2, 3, 5 and 6-bit products byte-equal to the codes widened onto the 8-bit tiles at 1, 3, 9 and 16 rows, within 0.32 of the float64 bound, split-K equal to the slice loop. - Qwen3.5-2B 4-bit: step, window, tree and prompt logits byte-equal to the build before. - The 2B requantized at 2, 3, 5, 6 and 8 bits: byte-equal to the same codes widened to 8 bits in all four modes, and step/window/tree byte-equal to the previous build, where 2 and 3-bit codes ran on the 4-bit tiles. - Qwen3.8-27B-oQ2: window, tree and prompt equal step over 300 ids; bench_concurrent --alone --serial at 1 and 2 streams all equal; about 45 to 64 tokens/s for one request, about 750 tokens/s prompt.
Prompt chunks ran modules of every width but 4 on the decode tiles, 16 rows at a time. affine8.cu now has qmm_prefill's GEMM over AffineN's tiles for 2, 3, 5, 6 and 8 bits: a 128 by 128 block on 2 by 4 warps, three stages, each weight rounded once to bf16 (s * q + b) and one fp32 chain over K. Its operands are the affine-4 prompt GEMM's, so a code of up to 4 bits gives the same bits as there. Checks on an RTX 4080 SUPER: - tf-cuda-test affine8: the prompt GEMM over 144 rows within 0.07 of a bound that allows for the bf16 weights; 2 and 3-bit byte-equal to the affine-4 prompt GEMM of the same codes, 5 and 6-bit to the 8-bit tiles'. - Qwen3.5-2B 4-bit: all four modes byte-equal to the build before. - The 2B requantized at 2, 3, 5, 6 and 8 bits: byte-equal to the same codes at 8 bits in all four modes, prompt included; decode modes unchanged. - Qwen3.8-27B-oQ2: window and tree equal step, step unchanged; bench 0 unequal. Prompts about 770 tokens/s (from 750): already bound by the bf16 tensor rate with fp32 accumulation. - Qwen3.5-9B MLX 8-bit: prompts about 1,940 tokens/s, from 1,520; bench at 1 and 4 streams 0 unequal.
…ffine_codes.cuh, one-line comments affine8.cu passed 600 lines with the prompt GEMM. The GEMM moves to its own kernel module and the code readers both use to a header; lean_check reports 528 problems, as on the base.
The weight loader's staging buffer is now Engine.init's and freed once the weights are on the card, so the server's stream budget counts that memory; the drafter's loader stages its own for its load.
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Stacked on #849, which is stacked on #836. Until those merge, this PR shows their commits too. The change here is
39c293a6..7cddf336, five commits, rebased onto #849's9b843c10(on #836's5e1c3fea).--kv-cache fp8was split out of this PR into #886, which is stacked on it.What this changes
Native 2, 3, 5 and 6-bit tiles (
39c293a6,11c8057e). #849 widened 2 and 3-bit codes onto the 4-bit tiles and 5 and 6-bit codes onto the 8-bit tiles, so a mostly 2-bit checkpoint took as much memory as the 4-bit one. Here every width gets tiles of its own: 2, 3, 5 and 6-bit modules are stored at their width, 7 and 8-bit modules on the 8-bit tiles, and 4-bit modules on the affine-4 tiles as before.affine8.cu's lane GEMV is templated on the width. Within each 64-group, a lane's 16 code pairs sit inbitswords: the first codes in the low halves, the second codes in the high halves.(0x4300 | c) - 128rebuilds each code exactly.qlinear.zig'sAffine8becomesAffineNand carries its width.AffineNKernelsresolves a gemv and a split-K kernel for each width.With this,
TensorFold/Qwen3.8-27B-oQ2takes 9.9 GiB on the device instead of about 16, so the 27B fits a 16 GB card.A prompt GEMM for those tiles (
b8ffd990,d3da9a18).affine_prefill.curuns qmm_prefill's prompt GEMM over AffineN's tiles, for 2, 3, 5, 6 and 8-bit modules. Before this, they ran prompts on the decode tiles, 16 rows at a time. The code readers move intoaffine_codes.cuh, which the GEMV and the GEMM share.The load staging buffer freed after load (
7cddf336). The buffer each projection is staged through on its way to the tiles now belongs toEngine.initand is freed once the weights are on the card, so the server's stream budget counts that memory. The drafter's loader stages its own. On the 27B oQ2, the startup line shows the model at 9.92 GiB instead of 10.29, leaving 3.8 GiB for streams instead of 3.4.Which sums change:
Receipt
Environment:
5e1c3fea, qwen3_5 cuda: mixed-width MLX checkpoints, 2 to 8 bits in groups of 64 #849 at9b843c10(before) and this PR at7cddf336(after), each built from its head.-Dsm=89.lmstudio-community/Qwen3.5-9B-MLX-4bit@b455506blmstudio-community/Qwen3.5-9B-MLX-8bit@950e0459TensorFold/Qwen3.8-27B-oQ2@086dcb02mlx-community/Qwen3.5-2B-MLX-4bit@93760be4--context 40960.Exactness:
bench_concurrent --alone --serial(levels 1 and 4, 4 cells each):"draft": falsetf-qwen35-cudaover 300 ids: window and tree equal step on the 2B and the 27B.With the DFlash2 drafter (
z-lab/Qwen3.8-27B-DFlash2@50307d4c). It is quantized to 4 bits at load through the drafter's own staging buffer, which7cddf336gives it. Served with--drafter --parallel 2 --context 8192:bench_concurrent --levels 1,2 --tokens 128 --reps 2 --alone --serial): 24/24 equal alone, and 12/12 drafted replies equal to"draft": false.bench_openai --tokens 128 --reps 3): 175 tok/s on code and 95 on chat, greedy. At T=1, 112 and 60. Undrafted, it is about 46.Decode speed (
bench_openai, one stream, medians over 5 reps; fibonacci-raw and gpu-chat-no-think at T=0 and T=1):Four streams together: 322–343 tok/s (9B 4-bit), 112–116 (9B 8-bit) against 111–113 on qwen3_5 cuda: mixed-width MLX checkpoints, 2 to 8 bits in groups of 64 #849.
Prompt speed: the cold first request's
ttft_sfrombench_cache --require-cold, on a 16,000-token prompt of the repo's docs (all rows report 0 cached tokens):Tests:
zig build test: 48/48 steps; 745 of 759 tests pass, 14 skipped, 0 fail.tf-cuda-test affine8: 24 cases over 2, 3, 4, 5, 6 and 8 bits pass.tf-qwen35-cuda, 300 ids, step / window / tree / prompt:5e1c3fea.bitsa weight over Affine4's padding, and a uniform 4-bit checkpoint keeps its sizes while other modules take their own width.Not run, and why:
fe9f07c2, before the prompt GEMM and staging commits and before the rebase onto5e1c3fea. I ran this head on sm_89 only.Quality and long context
The quality suite covers tools, JSON, IFEval, GSM8K, MGSM, MMLU, HumanEval (in Docker) and long-context needles and facts, at a 40,960-token window. Builds: #836 at
153d6b43, and this PR's code at its prompt-GEMM commit, both before the rebase onto5e1c3fea. That rebase changes attention only when streams of different lengths share a forward. One stream's logits are byte-equal before and after it in all four modes (2B, mixed-width 2B and 27B), so these single-stream results carry over.The 9B 4-bit scores are identical on both builds, down to the GSM8K misses.
The 27B oQ2's weak scores are the checkpoint's own: its recipe stores the LM head and the MLP and linear-attention input projections at 2 bits. I checked the engine against an independent fp32 numpy forward of Qwen3.5, written from the HF reference.
Long context with bf16 caches, one stream (
--parallel 1), before the rebase as above:#886 has the same runs with fp8 caches, at 256k.
Checklist
"draft": false, a resumed prompt equals a fresh one, and concurrent equals solo. This engine keeps no prompt cache on CUDA, so a resumed prompt is a fresh one.fe9f07c2(in the comments). Metal was not run.Limits
affine_prefill.fatbintoo.