Extends dqn_nan_check_fused_f32_kernel to handle 24 slots (12 NaN-only +
12 ISV-threshold). Per-slot thresholds computed inline in the kernel
from a single q_abs_ref_eff arg (no HtoD per step; no separate
thresholds buffer needed). Slot index → threshold mapping:
- 12-15 (slots 36-39): Adam m ≥ 100 × q_abs_ref_eff
- 16-19 (slots 40-43): Adam v ≥ 1e6 × q_abs_ref_eff²
- 20-21 (slots 44-45): Weight max ≥ 1e3 × q_abs_ref_eff
- 22 (slot 46): target_q ≥ 95 × q_abs_ref_eff (= 9.5 × max_abs_target_q)
- 23 (slot 47): atom span ≥ 190 × q_abs_ref_eff (= 9.5 × max_atom_abs × 2)
nan_check_buf_ptrs/lens resized 12→24 entries (mapped-pinned host
write at construction). populate_nan_check_meta extended with 4 new
args for IQN Adam m/v ptr+len (Option<u64>/Option<usize> — null when
IQN inactive).
Grid: 12 → 24 blocks. Single launch covers all 24 backward-path
diagnostic slots. Slot 31 (deferred) + slots 33-35 (inline elsewhere)
+ slots with null IQN entries no-op via the kernel's null-pointer
guard.
q_abs_ref_eff = max(isv[Q_ABS_REF=16], 1.0) — ε on multiplier per SP1
pearl; cold-start ISV (~0) gives q_abs_ref_eff = 1, so all thresholds
floor at their ε-floor multiplier × 1.
SP3 Mech 5 closes the diagnostic instrumentation loop — slots 36-47
fire when their threshold is exceeded, providing observability for
SP3's other 4 mechanisms' effectiveness. Fail-safe: if SP3 fix doesn't
fully resolve F1 NaN, slot 36-47 firing pattern guides the next
iteration.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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