Skip to content

[dev] Fix GDN DTensor splitting for FSDP checkpointing #4799

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
wplf merged 1 commit into from
May 15, 2026
Merged

[dev] Fix GDN DTensor splitting for FSDP checkpointing #4799

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 9 additions & 1 deletion megatron/core/transformer/fsdp_dtensor_checkpoint.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
make_fsdp_dtensor,
)
from megatron.core.distributed.fsdp.src.megatron_fsdp.uneven_dtensor import (
split_dtensor,
uneven_dtensor_to_full_tensor,
)
from megatron.core.distributed.fsdp.src.megatron_fsdp.utils import (
Expand Down Expand Up @@ -463,12 +464,19 @@ def offset_slice(s, offset):

def split_gdn_fused(data, dist_param, split_sizes, split_dim):
"""Split a fused GDN projection DTensor into per-component DTensors."""
total_split = sum(split_sizes)
if isinstance(data, DTensor) and data.shape[split_dim] == total_split:
return list(
split_dtensor(
data, split_sizes, dim=split_dim, update_uneven_dtensor_chunk_meta=True
)
)

fsdp_slice = dist_param.megatron_fsdp_slice
dist_index = dist_param.megatron_fsdp_dist_index
tp_mesh = dist_index.get_submesh([dist_index.tp_dim], is_expert_parallel=False)

data_size = data.numel() // tp_mesh.mesh.numel()
total_split = sum(split_sizes)
elems_per_unit = data_size // total_split

local_tensor = data.to_local()
Expand Down
Loading