Files
foxhunt/crates
jgrusewski adcbd6f0df fix: two-phase vaccine dot+norm reduction (3rd atomicAdd hang on H100)
gradient_dot_and_norm kernel used atomicAdd with 1264 blocks to compute
dot(g_train, g_val) and |g_val|² — same H100 L2 contention pattern as
the grad_norm hang. Replaced with two-phase: per-block partials + single-
block finalize (gradient_dot_norm_finalize). Zero atomicAdd.

Also added step-0-only per-phase GPU syncs to catch any remaining hangs
immediately (forward, aux, conditional, Adam, PER — only on step 0).

TODO: Causal intervention runs 14 full cuBLAS forward passes per step.
Should be optimized (batched or reduced frequency).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-06 21:47:25 +02:00
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