* If (legal) non-uniform data type signatures are used in ibcast
then the chosen algorithm may fail on the request, and worst case
it could produce wrong answers.
* Add an MCA parameter that, by default, protects the user from this
scenario. If the user really wants to use it then they have to
'opt-in' by setting the following parameter to false:
- `-mca coll_libnbc_ibcast_skip_dt_decision f`
* Once the following Issues are resolved then this parameter can
be removed.
- https://github.com/open-mpi/ompi/issues/2256
- https://github.com/open-mpi/ompi/issues/1763
Signed-off-by: Joshua Hursey <jhursey@us.ibm.com>
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