CUDA: optimize MMQ int8 tensor core performance #8062
Merged
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This PR adds the following optimizations for the CUDA MMQ kernels using int8 tensor cores:
ldmatrix
PTX instruction to load data in blocks of 16 bytes instead of 4.Performance vs. master MMQ
Performance vs. master FP16 cuBLAS
I now consider the performance good enough that I think MMQ should be made the default again; the performance for small quants is still suboptimal but for those I think the memory savings outweigh the hit to speed. I would prefer to do the default change in a separate PR.