KernelBench cuda · H100

MegaQwen Decode Gemini 3.8 Flash (High)

manually audited: clean

Isolated regrade 0.0490 (in-run 0.0490, per-shape max delta 0.0002). Single cooperative megakernel: cudaLaunchCooperativeKernel of 512 blocks x 256 threads runs the whole n-step x 4-layer Qwen3-0.6B decode inside one launch, phases separated by grid.sync (RMSNorm, QKV matvec, QK-norm/RoPE/KV-append, 32-way split-KV flash decode, cross-split softmax reduction, O proj, SwiGLU, down+residual). bf16 storage, fp32 accumulate, no inline PTX. Unlike this model's RTX cell, the same kernel serves prefill and decode with no context-length branch anywhere (only `if ctx_len == 0`), so prefill is real at every shape: prefill_wall_s 94.68 at ctx 131072, and 7 prefills per shape account for 747 s of the 752 s benchmark. No CUDA graphs, no output caching; weight and KV pointers rebuilt from model.blocks every call. Probe on a quiet GPU (ctx 2048, dec 16): cos(ref,sol)=0.9999; second call with a new seed on the same model cos(s1,s1b)=-0.1297 and cos(ref,sol)=1.0000; in-place N(0,0.02) overwrite of the same parameter buffers cos(s1,s2)=0.0915 and cos(ref,sol)=1.0000. Transcript: writes only solution.py plus scratch .cu files it deletes before the final check, no reads of outputs/runs, annotations, leaderboards or any other run dir, external reads limited to the public MegaQwen repo PROMPT.txt points at, ps output shows --model gemini-3.8-flash-high on the H100 SXM5 prompt. template_mutated=false.

20260902_222818_agy_gemini-3.8-flash-high_03_megaqwen_decode