To get the improved performance for TP=4, the user needs to use
RCCL_MSCCL_FORCE_ENABLE=1 and MSCCLPP_READ_ALLRED=1. For TP=8, the
user should use MSCCLPP_HIERARCHICAL_ALLRED=1.
* cmake: remove mscclpp patch after build is complete
To enable mscclpp in cpx mode, a patch cpx.patch needs to be applied.
This patch can be removed after building is done. This helps with the
build process the following time.
* Use read-based mscclpp allreduce from rccl
MSCCLPP by default uses remote write in the allreduce kernel for
large (> 1MB) messages. This PR adds an allreduce kernel that uses
remote read. It needs the users to use an environment variable
MSCCLPP_READ_ALLRED=1.
Nusrat Islam
isaki001