[mpiwg-rma] [EXTERNAL] Re: MPI_WIN_CREATE for intercommunicators

Jeff Hammond jeff.science at gmail.com
Wed Jan 22 12:09:46 CST 2014

On Wed, Jan 22, 2014 at 11:53 AM, Barrett, Brian W <bwbarre at sandia.gov> wrote:
> On 1/22/14 3:41 AM, "Thomas Jahns" <jahns at dkrz.de> wrote:
>>Hello Maik,
>>On 01/22/14 10:14, maik peterson wrote:
>>> thomas, today you should start thinking about other possibilities
>>> to solve your problem. this mpi rma stuff is crappy.
>>I guess that very much depends on your kind of machine. We've found it to
>>very nice with MVAPICH, not so great with PE and OpenMPI.
> Another way to put it; it really depends on how much work your MPI
> implementor has put into one-sided for your hardware.  MVAPICH has put in
> a good deal of effort to use IB-natvie RDMA semantics when implementing
> MPI one-sided.  Open MPI has not put that effort into IB (it has for
> another network, but that's a different story), so the performance is much
> lower.  Open MPI's largely driven by squeaky wheels, and that wheel's been
> pretty quiet :)..

Are you saying that if I make a big deal about OpenMPI's RMA warts on
your list that you all will make it MPI-3-feature-complete and perform
really well?

Or maybe you are using squeaky as a synonym for remunerating :-)


Jeff Hammond
jeff.science at gmail.com

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