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brokkr-smithy flagged that R49 F02's name-pool token splits were measured with the Qwen3.5-2B tokenizer, so the dense-Qwen3 carrier ruling invalidates them. Measured rather than left on their critical path; handed over as input to their re-check, since the dictionary and the adjudication are theirs. The multi-token property strengthens on the chosen carrier: pool multi-token 88.0% -> 90.3%, mean tokens 2.33 -> 2.46. A smaller vocabulary fragments more, so Qwen3's 151,936 splits names into more pieces than Qwen3.5's 248,320. The operator's requirement that names be multi-token, so the drafter reconstructs them from the prefix instead of recalling one embedding, is better served after the ruling. Positive control: the Qwen3.5 column reproduces F02's published figure on the same pool and tokenizer (F02 89% / mean 2.35; here 88.0% / 2.33), so the instrument recovers a known-true value before being asked about an unknown one. The pool is deduped across locales, which reconciles male_given and female_given exactly against the dictionary's own totals block.
Training throughput probes
Instruments for finding where a training step's time actually went. Written
2026-08-24 during the Gemma-4 26B-A4B ERP/RP tune investigation; the lessons
they produced live in
docs/pfi/training-throughput-playbook.md.
These are diagnostic instruments, not production code. They hard-code paths for that run. Adapt the constants at the top; keep the measurement design.
The probes
| script | settles | GPU | runtime |
|---|---|---|---|
step0_mask.py |
mask band structure; which layers keep the is_causal fast path |
no | ~30 s |
step2_padding.py |
padding waste, length distribution, CE chunk sizing | no | ~2 min |
step_bucket.py |
bucketing gain, bucket-size sweep, source diversity | no | ~3 min |
step1_profile.py |
scaling fit, padding penalty, CE wall clock, kernel table | yes | ~15 min |
Run in that order. Only the last needs the real checkpoint, and it wants an
idle card — it loads ~48 GiB and peaks near 77 GiB at 2 × 16,384.
Design rules worth preserving when you adapt these
step1_profile.py reuses the harness's own discover_target_modules and
replicates its compute_loss byte-for-byte rather than re-implementing the
step. A probe that reimplements the training step measures the probe. If you
port this, keep the import from the real harness.
step0_mask.py needs no weights and no GPU — SDPA backend selection and
mask construction depend on shapes, dtype and mask presence, not on weight
values. That is what makes the correctness assertion cheap enough to run before
every job.
The scaling test takes three points, not two. Two points over three plausible terms (quadratic, linear, fixed-per-batch) is underdetermined; see playbook §1.1 for the hour that cost.
step_bucket.py sweeps bucket size deliberately. The first version
re-sorted within each bucket, which silently collapsed every bucket size to a
full global sort and made the sweep a no-op. If you change the pairing logic,
check that the sweep still varies something.
Raw evidence
step1-profile-output-2026-08-24.txt is the unedited output of the run the
playbook's numbers come from — scaling points, padding penalty, CE timing, and
the full key_averages() kernel table. Kept so the claims can be re-derived
rather than taken on faith.
⚠ That table double-counts: key_averages() lists both the ATen op and the
CUDA kernel it launched, each carrying the same self device time. Sum device
kernel rows only. See playbook §3.4.