Add AllReduce distributed strategy design #373
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QiJune
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@@ Coverage Diff @@
## develop #373 +/- ##
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- Coverage 87.75% 87.69% -0.07%
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Files 33 33
Lines 1503 1503
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- Hits 1319 1318 -1
- Misses 121 122 +1
Partials 63 63
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QiJune
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shendiaomo,
typhoonzero,
wangkuiyi and
Yancey1989
Yancey1989
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Oct 28, 2020
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| Single-process multi-GPU is not the recommended mode, | ||
| becase of its overhead of scatter/gather and GIL contention in every forward pass. | ||
| So, let's focus on DistributedDataParallel. |
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GoTorch does not have GIL, does single-process multi-GPU mode fits GoTorch?
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The answer is no. There are two reasons:
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The overhead of scatter/gather is also nonnegligible. We once use scatter/parallel do/gather to support multi-GPU AllReduce in Paddle with C++. From the experience, the speedup ratio is not very good.
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We could only use scatter/gather in multi-GPU of one node. It could not be scaled to multi-node multi-GPU.
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Here is for beter review