Frank
49e8dfff66
halogen-flash-server is ACTIVE again with its 2026-09-16 measured ledger (budget 33.5 GiB against a need of 27.2 — no clamp — and 14.7 GiB left for everything else), ik_llama.cpp is retired with its measurements kept as the record of why, and the new frank-small runbook covers the -mtp file, the 64 KiB/token KV arithmetic, the MTP contract, and the reasoning_effort trap that cost me every subagent on the endpoint. AGENTS.md: topology, Active Services, runbook index, and three new llama.cpp lessons (MTP is a property of the file; --jinja is what `tools` needs; a model's template can reject the harness's thinking level). Three pre-existing defects found while editing it: a truncated sentence mid-file, a harness path that does not exist on either server, and the benchmarking stop/mask recipe still calling frank-large a root unit. Truthfulness notes worth keeping: the co-tenant stall NOTE prints again, so the claim that it "no longer prints" is gone and the three observed block counts are recorded instead of a guessed threshold; and the Observability page says out loud why frank-large has no scrape job rather than leaving a silent absence.
126 lines
7.2 KiB
Markdown
126 lines
7.2 KiB
Markdown
---
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type: reference
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description: frank-large on Dankclaw serving the mradermacher Qwen3.8-Flash-Next-Uncensored i1-Q4_K_M GGUF via ik_llama.cpp on the RTX 3090 + Strix Halo hybrid — measured performance envelope, root-cause analysis, tuning levers, and traps
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tags: [llm, frank-large, ik_llama, dankclaw, rtx3090, strix-halo, performance]
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timestamp: 2026-09-16T03:30:00-07:00
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---
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# frank-large — ik_llama.cpp, Qwen3.8-Flash-Next-Uncensored i1-Q4_K_M
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**RETIRED 2026-09-16, after one day.** Replaced by [[halogen-flash-server]],
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which was the runtime before it as well — the fleet went ik → halogen → back.
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Its unit, env, serve script and the Qwen-Sharp template are archived in the repo
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under `scripts/.AGENTTRASH/*.ik-llama.cpp` and `*.ik-llama-qwen-sharp`, and the
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payload, build and chat template stay on disk. The measurements below are not a
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stale plan: they are the complete account of what this model costs on this
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hardware, and they are why the fleet went back. It served
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`mradermacher/Qwen3.8-Flash-Next-Uncensored` (111 GiB GGUF + mmproj-f16) at
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`192.168.0.143:7770` while it ran.
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## Shape
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- Runtime: ik_llama.cpp master `d85a1d7`, built at
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`/home/dank/GitPackages/ik_llama.cpp/build` with `-DGGML_CUDA=ON
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-DCMAKE_CUDA_ARCHITECTURES=86 -DGGML_AVX512=ON -DGGML_AVX512_VBMI=ON
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-DGGML_AVX512_VNNI=ON -DGGML_AVX512_BF16=ON -DLLAMA_CURL=OFF`.
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- Unit: **root systemd unit** `/etc/systemd/system/frank-large.service`
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symlinked to `scripts/frank-large.service` in the repo; enabled at boot;
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`Restart=always`. Serve script `scripts/serve-frank-large.sh` + env
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`scripts/frank-large.env`.
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- Topology: 3090 (PCIe x4 in the M.2 dock, link downgraded from x16) carries
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dense/attention/KV (~11.5 GiB); ALL MoE expert tensors (~84 GiB) and the
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~33 GiB PLE n-gram table stay in LPDDR via CPU buffers.
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- Client contract: greedy default (`--temp 0.0`), reasoning on (deepseek
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format, unlimited budget), vision via mmproj, slot-state persistence under
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`scripts/slot-state`, 262144 ctx, 1 slot.
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## Measured performance envelope (2026-09-15/16 campaign, all single-instance verified)
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| config | decode tok/s | prefill tok/s | verdict |
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|---|---|---|---|
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| shipped (T16, `-ot exps=CPU`, NO_PINNED_WEIGHTS) | **3.8-4.0** | ~193 at 1.8k / 191 at 32k | shipped |
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| T8 / T4 / T2 / T1 | 4.18 / 4.20 / 4.26 / 3.97 | small-prompt only | decode flat across threads |
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| `-ncmoe 42` (6 layers' experts on GPU) | 4.54 | 32 (small prompt) | VRAM 22.0/24.6 GiB — fragile |
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| `-ncmoe 48 -thp` | 4.60 | 18 | **110 GiB anon host buffer — co-tenant killer, never ship** |
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| `--prefetch-experts` | 4.03 | — | no effect (page cache already resident) |
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| `--defer-experts --defer-ple -thp` | crashes | — | experts under `-ngl 999` still target CUDA0 → cudaMalloc OOM |
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| mainline llama.cpp `37b53fd` (`--n-cpu-moe 48`) | **1.01** | 34 | ruled out — CPU MoE kernels 4x slower than ik's iqk |
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- Large-prompt prefill ≈ 192 tok/s is the **CPU AVX512-VNNI compute ceiling**
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for CPU-resident experts (expert weight reads amortize across the batch;
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compute-bound). Halogen's "4x llama.cpp family" prefill claim is therefore
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unreachable with experts on CPU — the physics caps hybrid MoE prefill here.
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- Decode is gated by a **serial per-token critical path**: ~100 CPU↔GPU
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backend splits per token (`graph splits = 100` in the log); the 3090 sits at
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**5% SM utilization** during decode; thread count does not matter (T1 ≈
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T16 ≈ 4 tok/s). The GPU sections are launch/sync-bound, not compute-bound.
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## Root cause chain (perf evidence)
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1. `perf` at T16: ~53% cycles in `ggml_graph_compute_thread` + ~37% in
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`ggml_compute_forward_mul_mat_id`, of which **~98% is the `pause`
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instruction** (thread-pool barrier spin). Actual vec_dot math: ~4%.
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2. T1 = T16 decode (3.97 vs 3.8-4.0) ⇒ the barrier spin is threads waiting on
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a serial critical path, not parallel overhead.
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3. GPU 95% idle during decode ⇒ the critical path is the GPU-section
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launch/sync overhead per split (x4 dock link, eager kernel launches).
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4. ik's CUDA-graph capture would collapse those launches but **aborts** on
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qwen4exp: the per-layer hyper-connection broadcasts (`ggml_repeat_4d`,
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4 sites in `src/graphs/build_qwen4exp.cpp`) resolve to a REPEAT node whose
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CUDA path does a capture-illegal operation
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(`CUDA error: operation not permitted when stream is capturing` → abort).
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5. Memory placement is NOT the lever: mmap-off/anon/THP/deferred variants all
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land at 3.8-4.6 tok/s.
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## Why the 30 tok/s halogen bar is out of reach (honest record)
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Halogen's engine held the whole 115.55 GiB w4b checkpoint resident in LPDDR
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(`HALOGEN_FLASH_PIN_TRUNK=1`) and served from one engine. This deployment must
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split 84 GiB of expert tensors across a 24 GB GPU + CPU, and every public
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runtime pays the split penalty above. Paths to >30 tok/s, in order of
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realism: (a) a runtime with capture-safe CUDA graphs + dedicated hc ops —
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mainline is building exactly this (ggml-org PR #28901 "qwen4exp: add hc ops");
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re-evaluate mainline when its hc-ops + graph handling mature; (b) experts on
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GPU — impossible, 84 GiB > 24 GiB; (c) a smaller model.
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## Upstream issues tracking the slow TG path
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ik_llama.cpp: #2374 (QSA opt POC), #2406 (single-threaded sigmoid), #2433
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(cache-miss full reprocess), #2460 (PLE history correctness). MTP/speculative
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decoding is unavailable for this GGUF — mradermacher stripped the NextN head
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(verified: no `blk.48.*`/nextn tensors in the file).
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## Traps (learned the hard way 2026-09-15/16)
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- **Pinned host buffers strand the host**: a default-policy start
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page-locks ~108 GiB (`CUDA_Host buffer`), evicting co-tenants into swap and
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starving sshd until a power cycle. `GGML_CUDA_NO_PINNED_WEIGHTS=1` + the
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serve-script guard exist for this. `-ncmoe N` with default NO_PINNED
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settings produces the same 108 GiB pinned buffer — never run it without the
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guard.
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- **Any `-ot`/`-ncmoe` override disables mmap** for the whole model load
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(`create_tensors` returns false → `ml.use_mmap = false`): the "mmap-backed
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CPU buffer" comment in the serve script is wrong on the mmap word; the
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buffer is anonymous. All placement variants perform alike anyway.
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- **`--defer-experts` does not keep experts off the GPU** under
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`-ngl 999` — only PLE defers (32.78 GiB). With ngl 999 the load dies with
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`cudaMalloc failed: out of memory` at ~79.7 GiB on device 0.
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- **The systemd unit self-heals through manual tests**: `pkill` the server and
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the unit respawns it ~4 s later (Restart=always) — two instances, port
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races, phantom measurements. For manual experiments:
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`sudo systemctl stop frank-large.service` first (it is a root unit; plain
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`systemctl --user` lines in older docs are stale), and restore with
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`sudo systemctl start frank-large.service`.
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- Verify "HTTP server listening" in the CURRENT log and
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`pgrep -xc llama-server` == 1 before trusting any measurement.
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- FA must stay ON — FA-off crashes the loader on this arch.
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- Do not run builds concurrently with decode measurements (`-j16` starves the
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service and corrupts both results).
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## Rollback
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Stop and disable the root unit, trash it, restore the halogen quadlet from
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`~/.AGENTTRASH/20260915-ik-swap/halogen-quadlet` to
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`~/.config/containers/systemd/`, `systemctl --user daemon-reload`, start;
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the .hgn checkpoint and the kingjones STRIX llama.cpp payload remain on disk.
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