[NCCL] Patch bfloat16 support (#67843)
Summary:
Patch bfloat16 support in NCCL, PR https://github.com/pytorch/pytorch/issues/63260 adds bfloat16 support but is
still not complete to enable bfloat16 for allreduce in end-to-end training.
This patch does the followings:
* fix minimum NCCL version from 2.9.7 to 2.10, NCCL adds bf16 support in
v2.10.3-1 (commit 7e51592)
* update bfloat16 datatype flag in `csrc/cuda/nccl.cpp` so that NCCL
operations like all reduce can use it
* enable unit tests for bfloat16 datatype if possible
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67843
Reviewed By: H-Huang
Differential Revision: D32248132
Pulled By: mrshenli
fbshipit-source-id: 081e96e725af3b933dd65ec157c5ad11c6873525
