[QST] why the implementation of f16xs8 mixed gemm is different between TRT-LLM and native cutlass mixed gemm example?
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Description
What is your question?
Dear cutlass team,
lets consider sm80 and f16s8, the example of f16s8 TN mixed gemm shown here is different from TRT-LLM implementation, specifically, to my knowledge, the TRT-LLM one added the dequantization scale, but the cutlass one did not. Then my questions are:
- Is the performance or accuracy of TRT-LLM adding dequantization scale better than cutlass native one in LLM linear cases?
- from here, I see the TRT-LLM one seems load operand B(s8) using LDS not LDSM, but I can't find the f16s8 LDS specialization in MmaTensorOpMultiplicandTileIterator, only find LDS specialization for TF32, which make me confused with the “LDS". Am I missing something?
Thanks your time!
cc @manishucsd @alexsamardzic @hwu36
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Research direction
Compare the native CUTLASS f16s8 TN mixed GEMM example linked from PR 1084 with TensorRT-LLM's fpA_intB_gemm_template.h and dq_mma_pipelined_finegrained.h. Trace the referenced MmaTensorOpMultiplicandTileIterator implementation for the sm80 path. Done means documenting the dequantization-scale and LDS/LDSM differences and answering their performance, accuracy, and specialization questions.
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- Tech stack
- cpp
- Domain
- hpc, machine-learning
- Issue type
- Documentation
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
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- Needs clarification
- Newbie friendliness
- 25/100