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[Megatron-FSDP] Add fsdp_all_gather_in_start_param_sync option in DDP Config#2627

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yanring merged 2 commits into
NVIDIA:devfrom
shjwudp:mfsdp_optional_ag_before_fwd
Jan 29, 2026
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[Megatron-FSDP] Add fsdp_all_gather_in_start_param_sync option in DDP Config#2627
yanring merged 2 commits into
NVIDIA:devfrom
shjwudp:mfsdp_optional_ag_before_fwd

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@shjwudp

@shjwudp shjwudp commented Dec 11, 2025

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What does this PR do ?

main PR: #3095

Add a switch to control whether to prefetch the first parameter group of M-FSDP before the forward loop.

  • Prefetching the first parameter group before the forward loop can help launch kernels earlier, help improving throughput.
  • Skipping this step ensures compatibility with CUDA Graph capture.

⚠️ For major changes (either in lines of code or in its impact), please make sure to first share discuss a design-doc with the team.

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@rapatel

rapatel commented Jan 26, 2026

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@shjwudp Can this be merged soon? Thanks.

@shjwudp shjwudp marked this pull request as ready for review January 27, 2026 06:18
@shjwudp shjwudp requested review from a team as code owners January 27, 2026 06:18
@shjwudp shjwudp self-assigned this Jan 27, 2026
@shjwudp shjwudp added Expert Review [deprecated] Apply this label to indicate that your PR is ready for expert review. module: megatron-fsdp labels Jan 27, 2026
@shjwudp

shjwudp commented Jan 27, 2026

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/ok to test 1804c8d

@yanring yanring enabled auto-merge January 29, 2026 16:07
@yanring

yanring commented Jan 29, 2026

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/ok to test 722c5cd

@yanring yanring added this pull request to the merge queue Jan 29, 2026
Merged via the queue into NVIDIA:dev with commit 8f8f735 Jan 29, 2026
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4 participants