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Long-context sliding window: val_bpb=1.1764#61

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Long-context sliding window: val_bpb=1.1764#61
saml212 wants to merge 1 commit intoopenai:mainfrom
saml212:sam/warmdown-quantization

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@saml212 saml212 commented Mar 19, 2026

val_bpb = 1.1764

Baseline: 1.2244. Improvement: -0.048 BPB / -0.087 nats.

15.88MB artifact. 600s training + 80s sliding window eval on 8xH100 SXM.

Approach

Train at 2048 tokens with low LR (0.02), high Muon momentum (0.99), and tight gradient clipping (0.3). Evaluate with overlapping sliding windows (stride=512) — every scored token sees 1536+ tokens of context, matching training length exactly.

Novel Findings

Train length is irrelevant with sliding window. Training at 2048 vs 4096 gives identical BPB (1.1764 vs 1.1765) when using sliding window eval. The window provides long context at eval — the model only needs to learn local patterns. Training at 2048 gets more steps and is strictly better.

Gradient clipping has a narrow sweet spot for long sequences. clip=0.3 beats both 0.0 (no clip) and 0.1 (too tight). Full sweep in README.

Batch=786K is optimal (vs default 524K). Swept from 393K to 1M.

Configuration

TRAIN_SEQ_LEN=2048 TRAIN_BATCH_TOKENS=786432 MATRIX_LR=0.02 SCALAR_LR=0.02
TIED_EMBED_LR=0.03 MUON_MOMENTUM=0.99 WARMDOWN_ITERS=3000 GRAD_CLIP_NORM=0.3
EVAL_SEQ_LEN=2048 EVAL_STRIDE=512

Full details, sweep data, and reproduction in README.md.

Novel finding: aggressive LR decay (WARMDOWN_ITERS=20000) reduces int8 quantization
penalty from 0.014 to 0.005 BPB. Combined with FP16 tied embeddings and moderate
NTK-RoPE extrapolation (eval@1408).

Full warmdown sweep across 10 values and detailed analysis in README.
@saml212 saml212 changed the title Warmdown-Quantization: val_bpb=1.2154 Long-context sliding window: val_bpb=1.1793 Mar 19, 2026
@saml212 saml212 changed the title Long-context sliding window: val_bpb=1.1793 Long-context sliding window: val_bpb=1.1780 Mar 19, 2026
@saml212 saml212 changed the title Long-context sliding window: val_bpb=1.1780 Long-context sliding window: val_bpb=1.1769 Mar 19, 2026
@saml212 saml212 changed the title Long-context sliding window: val_bpb=1.1769 Long-context sliding window: val_bpb=1.1764 Mar 19, 2026
South-33 added a commit to South-33/parameter-golf that referenced this pull request Mar 19, 2026
- add a PR-audit research log entry covering the clean takeaways from pull requests openai#36 through openai#70
- promote long-context training plus matching long-context eval as a first-class clean branch based on PR openai#61 and PR openai#63
- refine mixed-precision export notes to emphasize using int6/int8 byte savings to fund wider MLP capacity, based on PR openai#65
- update the current snapshot and research thesis so future agents do not over-focus on exporter-only ideas after the broader PR sweep
South-33 added a commit to South-33/parameter-golf that referenced this pull request Mar 19, 2026
- fix the PR-audit notes to attribute the long-context branch to PR openai#65 rather than PR openai#61
- record PR openai#61 as schedule-side evidence about long warmdown reducing quantization damage
- keep the ideas backlog aligned with the actual GitHub PR content before using it for next-step decisions
@saml212 saml212 force-pushed the sam/warmdown-quantization branch from 50225c5 to 4a65f69 Compare March 19, 2026 15:51
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