Refactor foreach allgather #1416
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Motivation
In the case of
len(params)==1,foreach_all_gatheris in low performance due to copyin operation.Besides, in the case of
_get_fused_paramsusage, local tensor of params are padded to the same size on each rank, this behaviour can avoid one all gather communication of num elements.Key Changes
params_shapes_across_groupparameter inforeach_all_gather, it aims to provide static shape information for theforeach_all_gatherrather than all gather num elements metadata.len(params)==1offoreach_all_gather, avoiding copyin operation and copyout metadata all gather. It's compatible whether we provide theparams_shapes_across_groupor not.