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# Record: 11L XSA-all + Full GPTQ + Parallel Muon + Selective Pruning

**val_bpb: 1.1171** (3-seed mean, std 0.0006) | **15.92 MB** max artifact | 8xH100 SXM, 600s

## Results (3 seeds, 8xH100 SXM)

| Seed | Steps | ms/step | Sliding BPB (s64) | val_loss | Artifact |
|------|-------|---------|--------------------|----------|----------|
| 1337 | ~7,100 | 84.2 | **1.1164** | 1.8851 | 15,920,050 bytes |
| 42 | ~7,100 | 84.2 | 1.1171 | 1.8861 | 15,921,954 bytes |
| 7 | ~7,100 | 84.2 | 1.1177 | 1.8871 | 15,914,654 bytes |

**Mean: 1.1171 | Std: 0.0006**

## Key Techniques

### XSA on All 11 Layers
Standard practice applies Exclusive Self-Attention to only the last 4 layers. Applying to all 11 forces cross-position information mixing from layer 0, improving representation quality. Zero new parameters — just a config change. -0.0016 BPB vs XSA-last-4 in ablation.

### Full Hessian GPTQ with amax-aligned QAT
- 256-sample calibration from training data for per-layer Hessian approximation
- Column-wise int6 quantization with Cholesky error compensation, block size 128
- QAT STE aligned to export quantizer using row-maximum (amax) clipping with [-32, 31] range
- Late QAT at threshold 0.15

### Parallel Muon Optimizer with Parameter Banking
- Weight matrices stored in contiguous parameter banks (qo_bank, kv_bank, mlp_up_bank, mlp_down_bank)
- 3-phase overlapped optimizer step: async reduce-scatter → batched Newton-Schulz orthogonalization → async all-gather
- Eliminates DDP double-communication overhead, achieving 84.2ms/step (~7,100 steps in 600s)

### Selective ±1 Magnitude Pruning
Post-GPTQ, sort quantized values at ±1 by reconstruction error (scale²), zero least-impactful first until artifact fits target. Binary search for exact target size. Targets only values whose removal causes minimal reconstruction damage.

### LZMA Compression
LZMA preset 6 replacing zstd-22 for model serialization. Better compression ratio on int6 quantized weights.

## Architecture

- 11 transformer layers, dim=512, 8 heads, 4 KV heads (GQA)
- 3x MLP expansion (hidden=1536) with **LeakyReLU(0.5)²** activation
- **XSA on all 11 layers** (Exclusive Self-Attention)
- Partial RoPE (16/64 dims) + NTK-aware scaling
- LN Scale Factor 1/sqrt(layer_idx+1)
- U-Net skip connections (5 encoder, 6 decoder)
- SmearGate temporal gating
- BigramHash (2048 buckets, 128-dim)
- Shared Value Embedding (dim=128, layers 9-10)
- FlashAttention 3 (Hopper native kernels)
- Orthogonal init, logit softcap 30, tied embeddings

## Training

- Parallel Muon optimizer (matrices): lr=0.025, momentum=0.99, WD=0.04, 5 Newton-Schulz steps
- AdamW (embeddings): lr=0.035, (scalars): lr=0.025, WD=0.04
- Gradient clip: 0.3
- Batch: 786,432 tokens/step, seq_len=2048
- Warmdown: 3,500 iters (wallclock-based)
- EMA (decay=0.997) + Tight SWA (every 50 steps, scale<0.2)
- Late QAT: STE int6 fake-quantization when LR scale<0.15

## Quantization & Compression

- Full GPTQ with 256-sample Hessian calibration, block_size=128, percdamp=0.01
- Int6 per-row with amax clipping, range [-32, 31]
- Selective ±1 magnitude pruning (target 15.9MB)
- Small tensors + tok_emb.weight in fp16
- LZMA preset 6 compression

## Requirements

```bash
pip install flash_attn_3 --find-links https://windreamer.github.io/flash-attention3-wheels/cu128_torch291
pip install zstandard sentencepiece
```

## Run Command

```bash
SEED=1337 TARGET_MB=15.9 torchrun --standalone --nproc_per_node=8 train_gpt.py
```

## Test Plan

- [x] 3 seeds run on 8xH100 SXM
- [x] All 3 seeds train in ≤600s
- [x] All 3 seeds artifact ≤16,000,000 bytes (max: 15,921,954)
- [x] Sliding window eval stride=64, consistent (std=0.0006)
- [x] No test-time training on validation data
- [x] No network calls during evaluation
Original file line number Diff line number Diff line change
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{
"author": "Raahil Shah",
"github_id": "raahilshah",
"name": "11L XSA-all + Full GPTQ + Parallel Muon + LZMA + Selective Pruning",
"blurb": "XSA on all 11 layers, Hessian-aware GPTQ with amax-aligned QAT, Parallel Muon optimizer with parameter banking, LZMA compression, selective ±1 magnitude pruning. LeakyReLU(0.5)² activation, EMA(0.997), Tight SWA, VE128, Partial RoPE 16/64, LN Scale, BigramHash(2048), U-Net skips.",
"date": "2026-03-24T00:00:00Z",
"val_loss": 1.88609770,
"val_bpb": 1.11705625,
"pre_quant_val_loss": 1.9210,
"pre_quant_val_bpb": 1.1386,
"bytes_total": 15921954,
"seeds": {
"1337": {"val_bpb": 1.11643730, "val_loss": 1.88505263, "bytes_total": 15920050},
"42": {"val_bpb": 1.11708034, "val_loss": 1.88613838, "bytes_total": 15921954},
"7": {"val_bpb": 1.11765111, "val_loss": 1.88710208, "bytes_total": 15914654}
},
"mean_val_bpb": 1.11705625,
"std_val_bpb": 0.00060726
}
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logs/autorun_1774351988_exp93.txt
val_bpb:enabled tokenizer_kind=sentencepiece tokenizer_path=./data/tokenizers/fineweb_1024_bpe.model
train_loader:dataset:fineweb10B_sp1024 train_shards:80
val_loader:shards pattern=./data/datasets/fineweb10B_sp1024/fineweb_val_*.bin tokens:62021632
model_params:26993756
mtp_num_heads:0 mtp_loss_weight:0.2 mtp_params:0
XSA:last_11 active_layers:[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
world_size:8 grad_accum_steps:1
sdp_backends:cudnn=False flash=True mem_efficient=False math=False
attention_mode:gqa num_heads:8 num_kv_heads:4
tie_embeddings:True embed_lr:0.035 head_lr:0.0 matrix_lr:0.025 scalar_lr:0.025
train_batch_tokens:786432 train_seq_len:2048 iterations:20000 warmup_steps:20 max_wallclock_seconds:600.000
seed:1337
warmup_step:1/20
warmup_step:2/20
warmup_step:3/20
warmup_step:4/20
warmup_step:5/20
warmup_step:6/20
warmup_step:7/20
warmup_step:8/20
warmup_step:9/20
warmup_step:10/20
warmup_step:11/20
warmup_step:12/20
warmup_step:13/20
warmup_step:14/20
warmup_step:15/20
warmup_step:16/20
warmup_step:17/20
warmup_step:18/20
warmup_step:19/20
warmup_step:20/20
step:0/20000 val_loss:6.9309 val_bpb:4.1049 train_time:0ms step_avg:0.02ms
step:1/20000 train_loss:6.9317 train_time:508ms step_avg:507.92ms
step:2/20000 train_loss:8.6935 train_time:551ms step_avg:275.26ms
step:3/20000 train_loss:7.5958 train_time:634ms step_avg:211.21ms
step:4/20000 train_loss:7.3349 train_time:719ms step_avg:179.72ms
step:5/20000 train_loss:7.2640 train_time:802ms step_avg:160.47ms
step:6/20000 train_loss:7.1177 train_time:888ms step_avg:148.02ms
step:7/20000 train_loss:6.9213 train_time:973ms step_avg:138.95ms
step:8/20000 train_loss:6.8020 train_time:1055ms step_avg:131.88ms
step:9/20000 train_loss:6.4159 train_time:1140ms step_avg:126.64ms
step:10/20000 train_loss:6.0442 train_time:1225ms step_avg:122.47ms
step:500/20000 train_loss:2.3884 train_time:43397ms step_avg:86.79ms
step:1000/20000 train_loss:2.2588 train_time:86679ms step_avg:86.68ms
step:1500/20000 train_loss:2.2048 train_time:130091ms step_avg:86.73ms
step:2000/20000 train_loss:2.0491 train_time:173631ms step_avg:86.82ms
step:2500/20000 train_loss:2.1520 train_time:217233ms step_avg:86.89ms
step:3000/20000 train_loss:2.1463 train_time:260825ms step_avg:86.94ms
step:3500/20000 train_loss:2.1626 train_time:304413ms step_avg:86.98ms
step:4000/20000 train_loss:1.9592 train_time:348016ms step_avg:87.00ms
step:4000/20000 val_loss:2.0459 val_bpb:1.2117 train_time:348059ms step_avg:87.01ms
step:4500/20000 train_loss:2.1078 train_time:391582ms step_avg:87.02ms
step:5000/20000 train_loss:2.0857 train_time:435127ms step_avg:87.03ms
step:5500/20000 train_loss:1.9993 train_time:478709ms step_avg:87.04ms
step:6000/20000 train_loss:1.9235 train_time:522228ms step_avg:87.04ms
swa:start step:6200
late_qat:enabled step:6365 scale:0.1498
step:6500/20000 train_loss:2.0609 train_time:566145ms step_avg:87.10ms
step:6884/20000 val_loss:1.9207 val_bpb:1.1375 train_time:600081ms step_avg:87.17ms
stopping_early: wallclock_cap train_time:600081ms step:6884/20000
peak memory allocated: 22851 MiB reserved: 23004 MiB
ema:applying EMA weights
DIAGNOSTIC post_ema val_loss:1.9190 val_bpb:1.1365 eval_time:2083ms
Serialized model: 106158518 bytes
Code size: 87330 bytes
gptq:building calibration model...
gptq:calibrating with 256 full training batches...
gptq:calibrated 68 layers in 46.5s
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
gptq_quantize: 66 GPTQ layers, 0 naive layers
selective_prune: 4098820 ±1 candidates, unpruned=15.18MB target=15.9MB
Serialized model int6+lzma: 15832720 bytes
Total submission size int6+lzma: 15920050 bytes
Total submission size int8+zlib: 15920050 bytes
final_int6_roundtrip val_loss:1.9247 val_bpb:1.1399 eval_time:14661ms
final_int6_roundtrip_exact val_loss:1.92469650 val_bpb:1.13991368
final_int6_sliding_window val_loss:1.8851 val_bpb:1.1164 stride:64 eval_time:85035ms
final_int6_sliding_window_exact val_loss:1.88505263 val_bpb:1.11643730
final_int8_zlib_roundtrip_exact val_loss:1.88505263 val_bpb:1.11643730
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