Fix HSDP with ShardDegree < 8 #3313
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j316chuck
approved these changes
May 23, 2024
bigning
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May 23, 2024
mvpatel2000
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May 23, 2024
mvpatel2000
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May 23, 2024
mvpatel2000
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May 23, 2024
eracah
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May 23, 2024
I guess at least unit test needs it ? lol |
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what
@j316chuck found HSDP with 1 node 2X4 device mesh run can't resume. rank 0 failed this checkpoint files broadcast . It's because rank 4 (which is in the same replica pg group as rank 0) doesn't join this collective call because of this if condition.
So the fix is to let all the first rank of shard pg group joins the broadcast , but only local rank 0 writes to file
test
1 node device mesh: 2 X 4
before:
[nccl timeout] mpt-125m-hybrid-resumption-1-node-tYv2bB
after:
mpt-125m-hybrid-resumption-1-node-pzWqX1
mpt-125m-hybrid-resumption-1-node-RV4ovO
2 node device mesh: 2 X 8 still works
mpt-125m-hybrid-resumption-1-node-NlOtP5
2 node device mesh: 4 x 4 works:
mpt-125m-hybrid-resumption-1-node-ajvSHb
checked the logging, rank 8 is not downloading any checkpoint files, but it got all files broadcast from rank 0