deepseek-ai / deepseek-ai/DeepGEMM

question about tmem barrier

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Description

I have a question about the comment here:

https://github.com/deepseek-ai/DeepGEMM/blob/54e22612409371d6364144b69086735beb54e98b/deep_gemm/include/deep_gemm/impls/sm100_fp8_fp4_mega_moe.cuh#L269

Since TMEM is consumed by both CTAs, the next line uses 2 * kNumEpilogueThreads. Shouldn't this barrier therefore use arrive at all CTAs instead?

Conversely, for tmem_full_barrier above, it seems that only the leader CTA calls arrive. Is my understanding correct?

Contributor guide

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Research direction

Start in deep_gemm/include/deep_gemm/impls/sm100_fp8_fp4_mega_moe.cuh around the cited line and compare the barrier calls there with tmem_full_barrier above. Read the surrounding TMEM and CTA synchronization flow to determine which CTAs should call arrive. Done means resolving whether the current barrier participation is correct and documenting or correcting the synchronization behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
hpc
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
35/100

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