ggml-org/llama.cpp b12287

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cuda : use MMVF for BF16 matrices of few rows at small batch sizes (#31959)

MMF tiles 32 rows per block, so a BF16 matrix with few rows (e.g. the
qwen4exp hyper-connection projections, 320 rows with K = 10240) runs only
a handful of blocks and leaves most SMs idle at batch sizes 2..8. MMVF
runs a block per row and wins there when K is long enough.

MMVF's cost grows with rows x batch while MMF's stays roughly flat in that
range, so use MMVF only while rows * ne11 * 256 <= nsm * min(K, max_k) and
K >= 1024. The budget scales with the SM count, which keeps GPUs with few
SMs (e.g. the A16) on MMF. Blackwell allows up to 8 columns and
max_k = 6144; older GPUs stop at 5 columns and max_k = 4096.

Add eval cases at 128x2560, 512x2560 and 320x10240 for n = 2, 3, 4, 5 and 8.