[OMPI devel] Cost for AllGatherV() Operation

[Tim Stitt]

Dear OpenMPI Developers,

I would be grateful if someone could briefly describe the cost 
(complexity) for the allgatherv() collective operation in the current 
release of OpenMPI.

For MPICH2 I believe the cost is ceiling(lg p). Can anyone comment on 
the algorithms and cost used in the OpenMPI implementation?

Thanks in advance,

Tim.