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42d958167a cuda : route sm70 to the Turing MMVQ nwarps table (#29753)
* cuda : route sm70 to the Turing MMVQ nwarps table

Volta (sm_70) has no MMVQ parameter table of its own and falls through
to GENERIC, which launches K-quant batch-1 decode (ncols_dst == 1) at
nwarps=4. sm_70 shares TURING's tuning: the K-quant vec_dot prefers
nwarps=2 there. Route sm_70 to the existing MMVQ_PARAMETERS_TURING
table in both the device and the host table selector.

Measured on one Tesla V100 32GB PCIe (PG500-216, driver 580.178.04,
CUDA 12.0.140) with Qwen3.8-27B Q4_K_M, tg128, interleaved A/B in 6
ABBA blocks with paired per-block deltas: +1.091 t/s = +3.17 %
(t = +49.0, all six per-block deltas positive); perplexity
bit-identical (6.3697 +/- 0.04066 both builds, wiki.test.raw). The
patched build's K-quant mul_mat_vec_q kernels launch at nwarps=2
(cubin EIATTR_MAX_THREADS) while Q4_0/Q8_0 stay at nwarps=4, and the
same measurement on the September master base gave +3.84 % (t = 85).

The tuning originates from the V100-focused fork anyei/llamacpp-v100
(MIT), commit b912d1b1e, which carries a dedicated
MMVQ_PARAMETERS_VOLTA table; a cubin-level comparison confirmed that
routing sm_70 to the existing TURING table is equivalent for the
K-quant batch-1 path this change affects, so this is the minimal
2-line form. https://github.com/anyei/llamacpp-v100/commit/b912d1b1e

Original-patch-by: anyei <angelyoelroblesmercedes@gmail.com>

* Update ggml/src/ggml-cuda/mmvq.cu

---------

Co-authored-by: tkittich <tkittich@gmail.com>
Co-authored-by: Johannes Gäßler <johannesg@5d6.de>
2026-10-01 15:21:26 +02:00
..
2024-07-13 18:12:39 +02:00