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

Thomas Jahns jahns at dkrz.de
Wed Jan 22 15:17:42 CST 2014


On Jan 22, 2014, at 19:56 , Jeff Hammond wrote:

> On Wed, Jan 22, 2014 at 12:16 PM, Barrett, Brian W  
> <bwbarre at sandia.gov> wrote:
>> On 1/22/14 11:09 AM, "Jeff Hammond" <jeff.science at gmail.com> wrote:
>>> 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
>>>>> work
>>>>> very nice with MVAPICH, not so great with PE and OpenMPI.

perhaps I should qualify my very brief original statement before it  
becomes more flammable: MVAPICH gave the best out-of-the-box  
performance on that particular system (IBM xSeries with FDR IB) and  
while OpenMPI (on the same machine) did give the desired performance  
improvements with RMA, base-line performance was lower for some yet  
undiscovered reason, but system adminstration will look into it. I  
have no doubt this could have been different. For PE we asked IBM what  
to do differently but have no final answer so far.

Regards, Thomas
Thomas Jahns
DKRZ GmbH, Department: Application software

Deutsches Klimarechenzentrum
Bundesstraße 45a
D-20146 Hamburg

Phone: +49-40-460094-151
Fax: +49-40-460094-270
Email: Thomas Jahns <jahns at dkrz.de>

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