[FSDPv2] Shard on the maximal dim of weights #7134
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JackCaoG reviewed May 29, 2024
| continue | ||
| spmd.mark_sharding(param, mesh, _prepare_spmd_partition_spec(param)) | ||
| spmd.mark_sharding( | ||
| param, mesh, _prepare_spmd_partition_spec(param, shard_maximal=True)) |
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should we make it configureable?
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No, not necessary... It shouldn't matter to the user...
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ok I think I get it.. We need to do a all-gather anyway before entering the layer and only one dimension is being sharded.
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Yea, that's right. If the 0th dim is like size of 8 (MoE) and we are sharding it on v5p-2048, it will be a disaster.
alanwaketan force-pushed the alanwaketan/fsdp_maximal branch from 701277f to 9dd39cc Compare JackCaoG approved these changes May 29, 2024
| Thanks Jack for approving the change. |
| Skip GPU to move fast. |
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Summary:
This pull request makes FSDPv2 to shard on the maximal dim of weights instead of the 0th dim.
Test Plan:
XLA_USE_SPMD=1 PJRT_DEVICE=TPU python test/spmd/test_fsdp_v2.py