[{"data":1,"prerenderedAt":153},["ShallowReactive",2],{"run:lego-p2lc-12500":3,"run-findings:lego-p2lc-12500":126},{"run":4,"config":17,"metrics":71,"curve":77,"assets":125},{"id":5,"title":5,"subtitle":6,"eyebrow":7,"date":8,"workspace":9,"commit":10,"tags":11,"verdict":16},"lego-p2lc-12500","2026-08 gap sweep Phase 2 2-BWD gate — raster_backward_range = last_contributor 単独 (vs 395.59s baseline)","Run summary · 2026-08 msplat gap sweep Phase 2","2026-08-16","splat","1feed29",[12,13,14,15],"p2-gap-sweep","2-bwd-last-contributor","gate-run","lego-12500","partial",[18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,68],{"key":19,"value":20},"dataset","\u002FUsers\u002Fotkrickey\u002Fdev\u002F3dgs-workspace\u002Fdatasets\u002Fnerf_synthetic\u002Flego",{"key":22,"value":23},"gt_convention","Premultiplied",{"key":25,"value":26},"iterations","12,500",{"key":28,"value":29},"seed","42",{"key":31,"value":32},"capacity","1,000,000 splats",{"key":34,"value":35},"sh_degree","3",{"key":37,"value":38},"loss","L1Ssim",{"key":40,"value":41},"lambda","0.200",{"key":43,"value":44},"ssim","window=7 sigma=1",{"key":46,"value":47},"backend.backward","Simd",{"key":49,"value":50},"backend.loss_path","Gpu",{"key":52,"value":53},"backend.emit_pairs","Original",{"key":55,"value":56},"backend.forward","F32",{"key":58,"value":59},"backend.dispatch","PerStage",{"key":61,"value":62},"backend.radix_scan","Cpu",{"key":64,"value":65},"backend.target_cache","true",{"key":67,"value":65},"backend.shader_fast_math",{"key":69,"value":70},"os_build","26.5.2 (25F84)",{"psnr":72,"wallclock":73,"wallclock_regress":74,"splats":75,"final_loss":76},36.1908073425293,"5m 36s",false,408752,"5.517549e-3",{"loss":78,"splats":109},{"iters":79,"values":94},[80,81,82,83,84,85,86,87,88,89,90,91,92,93],1,1000,2000,3000,4000,5000,6000,7000,8000,9000,10000,11000,12000,12500,[95,96,97,98,99,100,101,102,103,104,105,106,107,108],0.5938450694084167,0.054076775908470154,0.014158269390463829,0.008471006527543068,0.007367284037172794,0.006614454556256533,0.006230855360627174,0.005994874052703381,0.005838850978761911,0.005738001316785812,0.005617116577923298,0.005531651433557272,0.005498033948242664,0.005517548881471157,{"iters":110,"values":111},[80,81,82,83,84,85,86,87,88,89,90,91,92,93],[112,113,114,115,116,117,118,119,120,121,122,123,124,75],5207,8218,180529,296375,348860,375026,389981,398267,402779,404919,405809,406651,407978,{"has_renders":74,"has_splat":74},[127],{"id":128,"title":129,"date":8,"status":130,"polarity":131,"category":132,"axes":133,"tags":134,"task_code":142,"related_runs":143,"delta_psnr":147,"delta_wallclock":148,"rank":149,"verdict":150,"impact_summary":151,"detail_path":152},"p2-last-contributor","P2 gap sweep Phase 2 — 2-BWD last_contributor で -15.0% (数学的同値)、STP 再判定は棄却","stable","positive","experiment",[80],[135,136,13,137,138,139,140,141],"gap-sweep","phase-2","backward","stop-the-pop","re-eval","function-constant","lego","2026-08 msplat gap sweep Phase 2 2-BWD \u002F STP 再判定",[144,5,145,146],"lego-lc-smoke-1k","lego-stp-c0-12500","lego-stack-lc-stp-12500","LC 12.5k gate: 36.183 → 36.191 dB = +0.008 dB (数学的同値実装、atomic 非決定性 guard ±0.1 内)","LC 12.5k gate: 395.59 → 336.33s = **-14.98%** (backward_raster -40.3%)。STP: -2.51% (gate 未達)、LC+STP スタック: 343.63s (LC 単独より +2.2%)","high","lc-adopted-minus-15-percent-stp-rejected-final","C0 (-48.4%) に続く Phase 2 第 2 弾で、backward 31.4% の新 bottleneck を kernel 側から -40.3% 削減。\u003Cstrong>Lego 12.5k = 336.33s で msplat 30K (220s) 比 1.53× まで縮小\u003C\u002Fstrong>し、gap sweep の目標 (≤2.0×) を達成した。実装は「forward が既に知っている打ち切り位置を backward に伝えるだけ」で数学的同値 — 品質を 1 bit も動かさずに backward の replay 計算量を ~40% 削った。STP 再判定は負の結果だが価値が高い: Phase 1a の -7.45% の正体が C0 と同じ page fault 削減だったことを分離実証し、「効果の重複を疑って再 bench する」protocol の正しさを裏付けた。次の bottleneck は forward rasterize 9.8% \u002F radix 13.5% \u002F SSIM 7.5% でいずれも trigger 25% 未達 — Phase 2 はここで完了、Phase 3 (再計測 + Pareto v3) へ。","\u002Ffindings\u002Fp2-last-contributor\u002F",1790227324507]