Update flash attention section in memory_optimizations.rst #9188
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Signed-off-by: cyanguwa <[email protected]>
jgerh
reviewed
May 22, 2024
jgerh
reviewed
May 22, 2024
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| Turn Flash Attention On and Off | ||
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| In the NeMo Framework, Flash Attention is supported through the Transformer Engine with the inclusion of Flash Attention 2. By default, Flash Attention is enabled, but the Transformer Engine may switch to a different kernel if the tensor dimensions are not optimal for Flash Attention. Users can completely disable Flash Attention by setting the environment variable ``NVTE_FLASH_ATTN=0``. | ||
| In the NeMo Framework, flash attention is supported through `Transformer Engine <https://github.com/NVIDIA/TransformerEngine/tree/main>`_ with both of the above implementations. Transformer Engine selects the appropriate implementation based on the input information (sequence length, number of heads, head dimension, etc), but when both implementations are applicable, Transformer Engine prefers cuDNN flash attention on Hopper+ architectures, and Tri Dao flash attention on Ampere-based architectures. To disable Tri Dao flash attention, users can set the environment variable ``NVTE_FLASH_ATTN=0``, and to disable cuDNN flash attention, users can set ``NVTE_FUSED_ATTN=0``. |
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Change to:
“In the NeMo Framework, Flash Attention is supported through the Transformer Engine, including both of the implementations mentioned above. The Transformer Engine selects the appropriate implementation based on input information such as sequence length, number of heads, and head dimension. When both implementations are applicable, the Transformer Engine prefers cuDNN flash attention on Hopper+ architectures and Tri Dao flash attention on Ampere-based architectures.
To disable Tri Dao flash attention, set the environment variable NVTE_FLASH_ATTN=0. To disable cuDNN flash attention, set NVTE_FUSED_ATTN=0.”
jgerh
reviewed
May 22, 2024
jgerh
reviewed
May 22, 2024
jgerh
reviewed
May 22, 2024
Signed-off-by: Charlene Yang <[email protected]>
Signed-off-by: Charlene Yang <[email protected]>
jgerh
approved these changes
May 24, 2024
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What does this PR do ?
Update the flash attention section in memory_optimizations.rst
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