Update the cuda API and enable tensor core for GEMM #9622
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kexinzhao
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wangkuiyi
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Apr 6, 2018
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fix #9625
fix #9626
cublasHgemm does true FP16 computation which is slow for non-Volta GPUs. So we use cublasGemmEx instead which does pesudo FP16 computation: input/output in fp16, computation in fp32, which can also be accelerated using tensor cores in volta GPUs.
By testing, I found that using GemmEx instead of Hgemm provides significant speed up on both Titan XP and V100 GPU.
Vgg16 imagenet batch size = 1, 1000 iterations total time spent on float16 mul op:
V100 GPU:
Hgemm vs GemmEx
1501 ms vs 451 ms
Titan Xp GPU:
Hgemm vs GemmEx
3259 ms vs 703ms
Tensor core example:
https://devblogs.nvidia.com/programming-tensor-cores-cuda-9/