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718b31d063
marlin-w4a16.{cuh,cu} + a gated hook in ggml_cuda_mul_mat (dense path), behind
GGML_CUDA_W4A16 + sm_120/121 + Q4_0/Q4_K + f32. Returns false -> MMQ, so the
default build is byte-identical. Verified on GB10: clean build, test-backend-ops
MUL_MAT 1103/1103, llama-bench pp512 unchanged (717.77 default / 718.26 flagged),
and GGML_CUDA_W4A16=1 reaches the seam ([w4a16] P1 warning) before falling back.
Source + apply steps under kernel/w4a16/ (DGX checkout is volatile). The frame the
P2 correctness kernel + P3 Marlin pipeline fill.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
1.4 KiB
1.4 KiB
W4A16 seam — how to apply to a llama.cpp / ggml-cuda checkout
Two source files + two one-line edits to ggml/src/ggml-cuda/ggml-cuda.cu. The build picks up the
new .cu via the existing file(GLOB) after a cmake -S . -B build reconfigure (no CMakeLists edit).
Files (copy into ggml/src/ggml-cuda/)
marlin-w4a16.cuhmarlin-w4a16.cu
Edit ggml/src/ggml-cuda/ggml-cuda.cu
-
Include — after the existing
#include "ggml-cuda/fp4-grouped-moe.cuh"(sibling-header style):#include "ggml-cuda/marlin-w4a16.cuh" -
Dispatch hook — immediately before the dense dispatch chain, i.e. before
if (!split && use_mul_mat_vec_f) {inggml_cuda_mul_mat(...)(afterconst int cc = ...):if (!split && ggml_cuda_w4a16_mul_mat(ctx, src0, src1, dst)) { return; }
Verify (P1 acceptance — met)
cmake --build build --target test-backend-ops llama-bench→ builds clean.test-backend-ops test -o MUL_MAT -b CUDA0→ 1103/1103 (byte-identical default).llama-benchdense Q4 pp512 → unchanged (~718, MMQ).GGML_CUDA_W4A16=1 llama-bench→ unchanged + stderr[w4a16] ... P1 seam - using MMQ(seam reached, gating passes on sm_121, falls back).
The kernel body (P2 correctness → P3 Marlin pipeline) replaces the TODO(P2/P3) block in marlin-w4a16.cu
and returns true once parity holds.