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snap-stanford / ogb

Benchmark datasets, data loaders, and evaluators for graph machine learning
https://ogb.stanford.edu
MIT License
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Some question about ogbn-mag NeighborSampling (R-GCN aggr) #413

Closed QiuJingkai closed 10 months ago

QiuJingkai commented 1 year ago

https://github.com/snap-stanford/ogb/blob/master/examples/nodeproppred/mag/sampler.py When I proflied this program with Nsight, I found that many Memcpy DtoH operations appeared dispersedly in the forward and backward stages of training. There is a small gap behind Memcpy DtoH. I want to know the reason why Memcpy DtoH appears, because the data copy from D to H in the compute process is very strange. In addition, these Memcpy DtoH appear behind DeviceReduceKernel and DeviceReduceSingleTileKernel. These operations also appear in a Linear. I also want to know what is the connection between Memcpy DtoH and DeviceReduceSingleTileKernel, and why these two operations always appear together？

weihua916 commented 10 months ago

This is best asked in torch geometric repo.