[Mpi3-rma] nonblocking MPI_Win_create etc.?

Rajeev Thakur thakur at mcs.anl.gov
Thu Sep 22 16:58:54 CDT 2011

In the new RMA, he could just call MPI_Win_create_dynamic once on comm_world and then locally attach memory to it using MPI_Win_attach. (And avoid using fence synchronization.)


On Sep 22, 2011, at 4:25 PM, Jeff Hammond wrote:

> I work with someone who has a use case for nonblocking window creation
> because can get into a deadlock situation unless he does a lot of
> bookkeeping.  He's creating windows on subgroups of world that can
> (will) overlap.  In order to prevent deadlock, he will have to do a
> global collective and figure out how to order all of the window
> creation calls so that they do not deadlock, or in the case where that
> requires solving an NP-hard problem (it smells like the scheduling
> problem to me) or requires too much storage to be practical (he works
> at Juelich and regularly runs on 72 racks in VN mode), he will have to
> serialize window creation globally.
> Nonblocking window creation and a waitall solves this problem.
> Thoughts?  I wonder if the semantics of nonblocking collectives -
> which do not have tags - are even sufficient in the general case.
> Jeff
> -- 
> Jeff Hammond
> Argonne Leadership Computing Facility
> University of Chicago Computation Institute
> jhammond at alcf.anl.gov / (630) 252-5381
> http://www.linkedin.com/in/jeffhammond
> https://wiki.alcf.anl.gov/index.php/User:Jhammond
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