[{"data":1,"prerenderedAt":178},["ShallowReactive",2],{"run:m4-12500-on-r2":3,"run-findings:m4-12500-on-r2":150},{"run":4,"config":18,"metrics":95,"curve":101,"assets":149},{"id":5,"title":5,"subtitle":6,"eyebrow":7,"date":8,"workspace":9,"commit":10,"tags":11,"verdict":17},"m4-12500-on-r2","M4\u002FA5 gate arm B (radix_scatter = simd_ballot): Lego 12.5k full run repeat 2","Run summary · 2026-09 第 5 回ゼミ milestones — M4 (A5 radix scatter simd_ballot)","2026-08-30","splat","d132cce",[12,13,14,15,16],"p3-radix-ballot","m4","a5","gpu-gate","lego","partial",[19,22,25,28,31,34,37,40,43,46,49,52,55,58,61,64,67,70,73,76,79,81,84,87,89,92],{"key":20,"value":21},"dataset","\u002FUsers\u002Fotkrickey\u002Fdev\u002F3dgs-workspace\u002Fdatasets\u002Fnerf_synthetic\u002Flego",{"key":23,"value":24},"gt_convention","Premultiplied",{"key":26,"value":27},"iterations","12,500",{"key":29,"value":30},"seed","42",{"key":32,"value":33},"capacity","1,000,000 splats",{"key":35,"value":36},"sh_degree","3",{"key":38,"value":39},"loss","L1Ssim",{"key":41,"value":42},"lambda","0.200",{"key":44,"value":45},"ssim","window=7 sigma=1",{"key":47,"value":48},"backend.backward","Simd",{"key":50,"value":51},"backend.loss_path","Gpu",{"key":53,"value":54},"backend.emit_pairs","Original",{"key":56,"value":57},"backend.forward","F32",{"key":59,"value":60},"backend.dispatch","PerStage",{"key":62,"value":63},"backend.radix_scan","GpuHierarchical",{"key":65,"value":66},"backend.radix_scatter","SimdBallot",{"key":68,"value":69},"backend.binning","Resident",{"key":71,"value":72},"backend.tile_sort","GlobalRadix",{"key":74,"value":75},"backend.submission","Chained",{"key":77,"value":78},"backend.target_cache","true",{"key":80,"value":78},"backend.shader_fast_math",{"key":82,"value":83},"os_build","26.6.2 (25G83)",{"key":85,"value":86},"backend.ssim_clear","HostMemset",{"key":88,"value":86},"backend.raster_grad_clear",{"key":90,"value":91},"backend.backward_uniform","HostBuffer",{"key":93,"value":94},"backend.lazy_c3_scratch","false",{"psnr":96,"wallclock":97,"wallclock_regress":98,"splats":99,"final_loss":100},36.05730056762695,"2m 6s",false,409074,"5.630053e-3",{"loss":102,"splats":133},{"iters":103,"values":118},[104,105,106,107,108,109,110,111,112,113,114,115,116,117],1,1000,2000,3000,4000,5000,6000,7000,8000,9000,10000,11000,12000,12500,[119,120,121,122,123,124,125,126,127,128,129,130,131,132],0.5938453674316406,0.05479905754327774,0.014673616737127304,0.008706759661436081,0.007766976952552795,0.006950200069695711,0.006466304883360863,0.006190439220517874,0.006050926633179188,0.005918469280004501,0.0057711051777005196,0.005692138336598873,0.005644109100103378,0.005630052648484707,{"iters":134,"values":135},[104,105,106,107,108,109,110,111,112,113,114,115,116,117],[136,137,138,139,140,141,142,143,144,145,146,147,148,99],5207,8257,181580,297513,350702,377197,391426,398820,402807,405024,406041,406971,408258,{"has_renders":98,"has_splat":98},[151],{"id":12,"title":152,"date":8,"status":153,"polarity":154,"category":155,"axes":156,"tags":158,"task_code":165,"related_runs":166,"delta_psnr":172,"delta_wallclock":173,"rank":174,"verdict":175,"impact_summary":176,"detail_path":177},"M4\u002FA5 radix_scatter simd_ballot 2段化 — 12.5k gate 採用、-14.9%、default flip","stable","positive","experiment",[104,157],3,[13,14,159,160,161,162,16,15,163,164],"radix-scatter","simd-ballot","tile-bin","sort-parity","adopted","default-flip","2026-09-seminar05-milestones — M4 (A5 radix scatter simd_ballot)",[167,168,169,5,170,171],"m4-12500-off-r1","m4-12500-on-r1","m4-12500-off-r2","m4-12500-off-r3","m4-12500-on-r3","12.5k 同一 session 交互 A\u002FB n=3: on **36.143 dB** (36.15227 \u002F 36.05730 \u002F 36.21933) vs off **36.121 dB** (36.19775 \u002F 36.01755 \u002F 36.14695) = **+0.022 dB**。task 指定 guard (on mean ≥ off mean − 0.05 dB) に **pass** (+0.022 > -0.05)。config header の絶対 guard (36.202 ± 0.1 dB、帯 [36.102, 36.302]) にも on\u002Foff とも **pass**。final splats は on 408,084 (408,408 \u002F 409,074 \u002F 406,770) \u002F off 409,363 (408,928 \u002F 411,049 \u002F 408,113) で on が -0.31% 少ない (既存 atomic 非決定性 chaos の範囲内、方向は一貫していない)。sort parity は `tile_offsets` で byte-exact だが、同じ parity report は `sorted_idx` の 0.217% (2105\u002F969838) に既知の tie-order 非決定性を記録しており、これが rasterize 順序ひいては atomic 加算順序に伝播するため end-to-end の PSNR は parity だけでは pin されない — したがって観測された小さい非方向性の PSNR 散らばりは想定内であり、M2 Tier1 gate (p3-tier1-bit-exact) が観測したような系統的分離は見られない","12.5k full run 同一 session 交互 A\u002FB n=3: **off 149.883s (σ 0.591%) → on 127.530s (σ 0.794%) = -14.914%**。3 pair 個別 Δ は -14.72% (r1) \u002F -15.15% (r2) \u002F -14.87% (r3) とレンジ 0.43 pt の高い一貫性。有意閾値 max(2σ_off,1%) = 1.182%、実測 Δ は**その 12.6 倍**。σ 非対称比 1.34× (off\u003Con) は汚染の典型署名とされる 3× を大きく下回り、on 側が GPU 律速でむしろ host jitter に鈍いという機構と整合する。replay bench (p3-radix-ballot 旧版、production default stack、n=3、GPU 専有未確認) の -12.9%〜-13.3% という directional 参考値とも整合し (12.5k full run のほうがやや大きい -14.9%、407k 固定 checkpoint 断面と 12.5k 平均 pair 数分布の違いで説明可能)、forward_submission=per_stage での radix 単独 gpu_ms -63.7% とも方向・大きさの両方で整合する","high","adopted-default-flip-radix-scatter-simd-ballot","tasklist A5 (radix は帯域 36% の latency 律速と算術証明済み) の実装検証。既存 O(lid) 逐次 threadgroup memory scan を simdgroup ballot 2 段化に置換し、BackendConfig `radix_scatter` の enum variant `simd_ballot` として追加、**2026-08-30 M4 GPU gate で default に採用**。sort parity は unit test 3 本 (境界サイズ 0\u002F1\u002F255\u002F256\u002F257\u002F1234\u002F100000、ties 多発 n=5000、3 種の radix_scan 実装すべて) と本番規模 (407,267 splats) `splat bench --parity` の両方で bit exact PASS。**12.5k Lego 同一 session 交互 A\u002FB n=3 (off-r1→on-r1→off-r2→on-r2→off-r3→on-r3、独立 10s load sampler で汚染監視、binary sha256 は series 前後で不変) で train elapsed 149.883 → 127.530s = -14.9%**、3 pair 個別 (-14.72% \u002F -15.15% \u002F -14.87%) が高い一貫性を示し、有意閾値 max(2σ_off,1%)=1.18% の **12.6 倍**という大差で通過。σ は off 0.59% \u002F on 0.79% (非対称比 1.34×、汚染の署名である 3× を大きく下回る)。**PSNR guard も pass** (on mean 36.143 dB ≥ off mean 36.121 dB − 0.05 dB、Δ +0.022 dB、両 arm とも config header の絶対 guard 36.202±0.1 dB にも収まる)。final splats は on 408,084 \u002F off 409,363 で -0.31% (既存 atomic 非決定性 chaos の範囲内)。session 開始時の ambient load 18.86〜22.8 (Spotlight `mediaanalysisd`\u002F`mds_stores` 再インデックス、reboot 後) という p2-s3 が破棄基準にした汚染クラスの中で実施したが、同一 session 交互設計と 3 pair の高い一貫性 (レンジ 0.43 pt) がこれを吸収したことを §0 で示す。**結論: 採用。`RadixScatterKind::default()` を `SimdBallot` に flip、`cargo test --workspace --release` 全 pass**。","\u002Ffindings\u002Fp3-radix-ballot\u002F",1790227325055]