Gahow Wang d422c68704 docs: KI-5 — correct cross-rank divergence attribution (pre-existing flaky) ...

The ~1-ULP cross-rank param divergence is NOT caused by coalescing: the
original ungrouped all-reduce is itself run-to-run nondeterministic on
this box (6 reruns: cross-rank diff {0, 0, 5.96e-8, 5.96e-8, 1.19e-7,
1.19e-7}), so the T8 test's `max|p0-p1| == 0.0` assertion is flaky here
(passes ~1/3 of runs) independent of T11. Diffs are ≤1.19e-7 (a few ULP,
numerically benign; loss-match stays ~6e-7). Noted as a follow-up to
loosen the assertion to a tight tolerance; coalescing was reverted purely
because it gives ~0 scaling benefit.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2026-06-16 09:42:13 +08:00

..

runs

docs: run v3 — TinyStories, dim512, val 1.30

2026-06-16 03:37:45 +08:00

00-build-chain.md

docs: backfill T1 build-chain

2026-06-15 15:12:55 +08:00

01-tensor.md

docs: Phase T2 — tensor abstraction

2026-06-15 15:12:55 +08:00

02-gemm-autodiff.md

docs: Phase T3 — GEMM fwd/bwd + finite-diff

2026-06-15 15:27:03 +08:00

03-autograd-engine.md

docs: Phase T4 — autograd engine

2026-06-15 15:53:55 +08:00

04-tiny-transformer.md

docs: Phase T5 — tiny transformer

2026-06-15 16:09:30 +08:00

05-training-loop.md

docs: Phase T6 — training loop

2026-06-15 16:30:14 +08:00

06-performance.md

docs: Phase T7 — performance

2026-06-15 17:00:29 +08:00

07-distributed.md

docs: Phase T8 — distributed data parallel

2026-06-15 17:15:49 +08:00

08-export-xserv.md

docs: T9 verification results (xserv == xtrain, dash5)

2026-06-15 17:37:46 +08:00

09-batched-forward.md

docs: Phase T10 — batched forward

2026-06-16 00:44:50 +08:00

known-issues.md

docs: KI-5 — correct cross-rank divergence attribution (pre-existing flaky)

2026-06-16 09:42:13 +08:00