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Subject: Re: [OMPI users] Open MPI vs IBM MPI performance help
From: Eugene Loh (eugene.loh_at_[hidden])
Date: 2010-12-22 13:16:45


I'm curious if that resolved the issue.

David Singleton wrote:

> http://www.open-mpi.org/faq/?category=running#oversubscribing
>
> On 12/03/2010 06:25 AM, Price, Brian M (N-KCI) wrote:
>
>> Additional testing seems to show that the problem is related to
>> barriers and how often they poll to determine whether or not it's
>> time to leave. Is there some MCA parameter or environment variable
>> that allows me to control the frequency of polling while in barriers?
>>
>> From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]]
>> On Behalf Of Price, Brian M (N-KCI)
>> Sent: Wednesday, December 01, 2010 11:29 AM
>> To: Open MPI Users
>> Cc: Stern, Craig J
>> Subject: EXTERNAL: [OMPI users] Open MPI vs IBM MPI performance help
>>
>> OpenMPI version: 1.4.3
>> Platform: IBM P5, 32 processors, 256 GB memory, Symmetric
>> Multi-Threading (SMT) enabled
>> Application: starts up 48 processes and does MPI using MPI_Barrier,
>> MPI_Get, MPI_Put (lots of transfers, large amounts of data)
>> Issue: When implemented using Open MPI vs. IBM's MPI ('poe' from HPC
>> Toolkit), the application runs 3-5 times slower.
>> I suspect that IBM's MPI implementation must take advantage of some
>> knowledge that it has about data transfers that Open MPI is not
>> taking advantage of.
>> Any suggestions?
>