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cuda: avoid short-query MMA FA crash with quantized V #189

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Merged
bri-prism merged 1 commit into from
Oct 8, 2026
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cuda: avoid short-query MMA FA crash with quantized V #189

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6 changes: 6 additions & 0 deletions ggml/src/ggml-cuda/fattn.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,12 @@ template <int DKQ, int DV, int ncols2>
static void ggml_cuda_flash_attn_ext_mma_f16_switch_ncols1(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const int cc = ggml_cuda_info().devices[ggml_cuda_get_device()].cc;
const ggml_tensor * Q = dst->src[0];
const ggml_tensor * V = dst->src[2];

if (turing_mma_available(cc) && ggml_is_quantized(V->type) && Q->ne[1] > 2 && Q->ne[1] <= 4) {
ggml_cuda_flash_attn_ext_mma_f16_case<DKQ, DV, 64/ncols2, ncols2>(ctx, dst);
return;
}

if constexpr (ncols2 <= 8) {
if (turing_mma_available(cc) && Q->ne[1] <= 8/ncols2) {
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