Float16 design doc #5313
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Float16 design doc #5313
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hedaoyuan
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Nov 6, 2017
doc/design/float16.md
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| float16 float_to_half_rn(float f); // convert to half precision in round-to-nearest-even mode | ||
| float half_to_float(float16 h); | ||
| ``` | ||
| which provides one-to-one conversion between float32 and float16. These twos functions will do different conversion routines based on the current hardware. CUDA/ARM instrinsics will be used when the corresonding hardware is available. When the hardware falls back to non-ARM cpu, software emulation will be performed to do the conversion. |
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When the hardware falls back to non-ARM cpu -> If the hardware or compiler level does not support float32 to float16 conversion.
doc/design/float16.md
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| A brief survey of float16 support on different hardwares can be found [here](https://github.com/PaddlePaddle/Paddle/issues/4853). A brief survey of existing float16 implementations can be found [here](https://github.com/Xreki/Xreki.github.io/blob/master/multi_data_types_in_dl_framework/ppt/float16_and_quantized_type.md). | ||
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| There are various natively supported float16 implementations on different hardwares/linear algebra libraries including half on cuda, float16_t on ARM processor, and Eigen::half on Eigen. |
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I think a more detailed description is needed here. Need to describe the support of float16 from the three levels of hardware, compiler, and library respectively.
- For nvcc compiler, after CUDA 7.5, the __half type is supported.
- For NVIDIA GPU, maybe after sm_6.0(or sm_5.3?)
- For gcc/clang? In the mobile, usually, clang compiler.
- For libraries. Currently, what libraries support float16 calculations?
This is important because of if we upgrade the environment, we need to know what the minimum environment to support is.
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Great point! A detailed description has been added. Thanks!
hedaoyuan
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Nov 7, 2017
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