The AGENTS.md lesson "`--ubatch-size` has an OPTIMUM on this stack" was load- bearing and over-general: it was measured on the 2x R9700 layer split, and the same knob on the CUDA 3090 behaves the opposite way (curve climbs monotonically to 2048). That difference is now the reason frank-small ships ubatch 2048, so the lesson names the backend it was measured on and points at the counterpoint. Adds the 2026-10-05 boot-pair A/B to the runbook (+4.6 % prefill at 8,928 tokens for 616 MiB, decode flat, the sub-ubatch prompt as the control), marks the superseded 21,276/2,849 VRAM row, and logs the day. The old "ubatch 2048 failed the scratch boot" line stays visible as what it was: a predecessor-shape observation, not a law.
9.8 KiB
type, title, description, tags, timestamp
| type | title | description | tags | timestamp | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| reference | frank-small on Dankclaw — llama.cpp, MiMo-V2.6 Q6_K, 2 x 200704, f16 KV | The active frank-small runbook — llama.cpp master (CUDA sm_86) serving bartowski's MiMo-V2.6-Distill-Qwen-9B Q6_K GGUF on the RTX 3090: two conversations of 200,704 tokens with fully unquantized f16 KV, vision through the bundled projector, and the boot-pair arithmetic that prices every pool change. |
|
2026-10-03 |
frank-small — llama.cpp MiMo Q6_K, 2 × 200,704, f16 KV
ACTIVE since 2026-10-03. The third shape Frank bought in two days on this card: the freed third slot paid for exact KV values (frank-small-llama-mimo-q5km documents that step and remains the rollback), and the ~3.5 GiB still free then paid for the Q6_K quant rung — the same file this endpoint served on 2026-10-01, come back as an upgrade rather than a compromise. The pool held at 401,408 (2 × 200,704); only the weights moved up.
Identity
| Host / device | Dankclaw (192.168.0.143), RTX 3090, 24,576 MiB |
| Endpoint | http://192.168.0.143:7771 — alias frank-small, /v1 OpenAI surface |
| Runtime | llama.cpp master, CUDA sm_86 build …/llama-master/build-cuda/bin/llama-server (GGML_CUDA_FA_ALL_QUANTS=ON) |
| Unit | root systemd frank-small.service (scripts/frank-small.service), User=dank, Restart=on-failure, LimitMEMLOCK=infinity |
| Serve script | scripts/serve-frank-small.sh, tunables scripts/frank-small.env |
| Weights | /home/dank/models/MiMo-Q6K/MiMo-V2.6-Distill-Qwen-9B-Q6_K.gguf — bartowski/MiMo-V2.6-Distill-Qwen-9B-GGUF Q6_K, 7,793,710,624 B, sha256 ef96d05a… (qwen3_5 hybrid: 32 layers, 8 full-attention + 24 Gated DeltaNet, native 262,144, no MTP tensors) |
| Projector | …/MiMo-Q6K/mmproj-MiMo-V2.6-Distill-Qwen-9B-f16.gguf — 918,166,048 B, sha256 ff348f… (hardlink of the Q5KM dir's copy, link-count-2 verified; the dir is self-contained) |
| Fetch | scripts/download-frank-small.sh — -f, byte count + LFS sha256 verified, --verify-only; both files verified against the pinned sha on the host before this deploy |
| Seam | tests/frank_small_unit.bats (argv assertions against a stub engine: payload path, slot geometry, KV pair, batch pair, projector opt-out) |
Shape and KV contract
--ctx-size 401408 --parallel 2 — llama.cpp divides the pool across slots,
so each conversation gets n_ctx_slot = 200704. CTX_SIZE MUST stay
divisible by PARALLEL; the seam enforces it. Both K and V are unquantized
(f16) — the flags stay explicit because --flash-attn must not be lost if V
ever goes back to q8_0 (the serve script pins it, the seam pins the pin).
The Q6_K rung is a weights-side spend only. File delta +917,585,920 B
(+875 MiB) against Q5_K_M, same KV, same slot geometry, same batch pair.
Priced from the measured Q5 boot at this shape (non-KV 7,986 MiB): the boot
landed 21,276 MiB used / 2,849 MiB true free — non-KV measured 8,732 MiB,
inside the 2–3 GiB floor, so the pool stayed at 401,408 and the
12,288-token step-down ladder was never climbed. Quote nvidia-smi's free
field, never total − used: the driver holds ~450 MiB of reserve the
subtraction hides (that error once overstated this card's slack by a
half-GiB).
Quant ceiling, evaluated and closed 2026-10-03 (Frank: stay here).
Q8_0 is the only rung above this one on the Hub (9,545,979,424 B = 9,104
MiB, +1,671 over Q6_K): at the live pool it would leave 1,178 MiB free —
under the floor — and the calibrated bandwidth law (it predicted this file's
94.4 t/s from Q5_K_M's 104.84 within 1 %) puts decode at ~72 t/s, a further
−24 % for the near-lossless rung. Fitting it was priced two ways (trim the
pool to 2 × 182,272 — which also breaks frank-large's 183,501-token
compaction-prompt fit by 1,236 tokens — or revert V to q8_0), and both
were declined. Re-open only on evidence the Q6_K residual matters.
Pool prices on this card come from boots, never formulas — the measured boot-pair table lives in frank-small-llama-mimo-q5km (Shape and KV contract) and still prices every rollback shape.
Compute-buffer geometry (2026-10-05)
BATCH_SIZE=4096 UBATCH_SIZE=2048 — both doubled from 2048/1024, and the trade
measured rather than assumed, because the predecessor shape recorded "ubatch
2048 failed the scratch boot" and this card has less free space than it did.
That failure was a different shape, and it did not reproduce here. The
service itself is the bench (one card holds one server, so no scratch port):
the old rung was re-booted through a transient FRANK_SMALL_ENV_FILE drop-in
and reproduced the 2026-10-03 boot byte-identically — 21,276 MiB used /
2,849 MiB free — which makes the ubatch the only variable in the comparison.
| Probe | ubatch 1024 | ubatch 2048 | Δ |
|---|---|---|---|
| Prefill, 8,928 tokens | 3,972 / 4,077 t/s | 4,207 / 4,212 t/s | +4.6 % |
| Decode, 128 tokens at that depth | 91.87 / 93.01 t/s | 93.81 / 94.27 t/s | noise |
| Prefill, 279 tokens | 2,675.7 t/s | 2,658–2,811 t/s | noise |
| VRAM used / free | 21,276 / 2,849 MiB | 21,846 / 2,279 MiB | −616 MiB |
Three readings:
- The gain only exists above the old ubatch. A 279-token prompt is shorter than either micro-batch, so it cannot see the knob — and it did not move. That is the control proving the 8.9k delta is geometry, not drift.
- Decode is flat, as every prior sweep on this card found. Ubatch is a prefill knob.
- The price is 616 MiB out of a 2.8 GiB margin. 2,279 MiB free is still
inside the 2–3 GiB band, at its bottom edge.
4096/1536is the middle rung, and the pool's 12,288-token (384 MiB) ladder in frank-small-llama-mimo-q5km is the other way to buy room back.
Why 2048 is right HERE while 512 was right on the R9700 sibling: the curve is backend-specific. The 2× R9700 layer split peaks at ubatch 512 and is 10 % off that peak by 2048 (frank-medium-batch-ubatch); on this CUDA card the curve climbs monotonically to 2048 (710 → 1,188 t/s on the 35B MoE sweep, 1,944 → 2,423 t/s on the Ornith 8k sweep, both with decode flat). Never carry a ubatch verdict across backends.
The logical --batch-size is VRAM- and throughput-neutral — two sweeps and this
A/B agree — so 4096 costs nothing and buys nothing by itself; it is here because
that is the pair the curve was measured at.
Measured on this shape (2026-10-03, Q6_K, 2 × 200,704, f16 KV)
| Check | Result |
|---|---|
| Boot to healthy | model + projector resident in ~2.3 s (load log 0.02.27), n_slots = 2, n_ctx_slot = 200704, loaded multimodal model, health 200; deploy e2e gate 33/33 |
| VRAM | 21,276 MiB used / 2,849 MiB free of 24,576 (nvidia-smi free, steady state) — inside the 2–3 GiB floor with exact V AND the higher rung. Superseded 2026-10-05 by the batch doubling: 21,846 / 2,279 — see Compute-buffer geometry |
| Decode, temp 0, no thinking | 94.44 tok/s on the identical 506-token probe that measured 104.84 on Q5_K_M — −10 %. Decode on this card is weight-bandwidth-bound, and Q6_K streams ~10 % more bytes per token; the quant rung buys quality with decode rate, measurably |
| Prefill | 2,229.9 t/s (same shallow probe; rates are depth-dependent, not comparable across probes) |
| Vision | 512×512 solid-red PNG → Red (277 prompt tokens — the image really reached the tower). See the probe-size trap in Client contract |
| Tools / thinking | native tool_calls, thinking in reasoning_content, thinking OFF unless enable_thinking: true (MiMo template default; models.yml ships it in extraBody) |
Client contract
llama.cpp surface, live-verified on this model family: model id frank-small,
native tools via --jinja (tool_calls in the response), thinking in
reasoning_content, vision via image_url content parts. Two vision
traps, both measured here:
- A top-level
imagesfield on/v1/chat/completionsis silently ignored and the model invents a color. - The probe image must be big enough to supply real image tokens. A
10×10 px solid-red PNG came back "The image is a video, so I can't see its
content" — the engine itself warns at boot that Qwen-VL wants ≥ 1024 image
tokens, and a postage-stamp image lands one patch below usable signal.
512×512 answers
Redin 19 tokens. Always probe vision with a ≥ 256 px image; a wrong-color answer from a tiny image is the probe's fault, not the endpoint's.
~/.omp/agent/models.yml sets contextWindow: 200704 — the PER-SLOT window,
so the harness compacts before llama.cpp answers a longer prompt with a 400.
Rollback
| Target | How |
|---|---|
| Q5_K_M at the same shape | scripts/frank-small.env MODEL_FILE=/home/dank/models/MiMo-Q5KM/MiMo-V2.6-Distill-Qwen-9B-Q5_K_M.gguf (+ MMPROJ_FILE in that dir) and the deployer default — buys back 875 MiB (3,571 free measured) and the 10 % decode rate (104.84 tok/s measured). Payload sha-verified on disk |
| 3 × 180,224 + q8_0 V | CTX_SIZE=540672 PARALLEL=3 CACHE_TYPE_V=q8_0 (measured 21,684 used / 2,441 free with Q5_K_M — Q6_K does NOT fit that shape inside the floor; pair them explicitly) |
| SGLang + INT8 | frank-small-sglang-mimo-v26 — payload staged to /home/dank/.AGENTTRASH/20261002-retired-llm-payloads/ |
When it misbehaves
Same decision tree as frank-small-llama-mimo-q5km (When it misbehaves):
No CUDA GPUs are available ⇒ nvidia-modprobe -u -c=0; a 400 naming
200,704 ⇒ the conversation outgrew one slot, not the pool; slow decode after
a shape change ⇒ check nvidia-smi for KV pushed into unified memory; queue
behind two long generations ⇒ the slot ceiling is two, by contract.