KernelBench hard · RTX PRO 6000

W4A16 GEMM Kimi K3 (256k)

manually audited: clean

Genuine fused W4A16 (int4-weight, bf16-activation) GEMM with four real paths dispatched from one C++ extension: an M==1 split-K GEMV using the lop3-magic bf16 dequant trick with fp32 FFMA accumulate and arrival-counter reduction; a cp.async + ldmatrix + mma.sync.m16n8k16 tensor-core kernel for M in [2,32] over lane-packed repacked int4 tiles; a 16-warp k6 tensor-core kernel for M in (32,256]; and a Triton fused-dequant tl.dot fallback for any other shape. Dequant folds live scales/zeros as s/256 and 32768+256*z magic constants, recomputed in the repack kernel whenever weights change. The only cache (PackCache) is keyed on w_q.data_ptr() plus a hash of the w_q/scales/zeros tensor _version counters and a per-Model-instance eid — a legitimate weight-repack cache, not output caching. Output y is freshly allocated (torch::empty) and recomputed from the live activation on every call. 0.2427 geomean peak fraction is a real regrade timing.

20260715_204409_kinetic-claude_kinetic-0715_07_w4a16_gemm