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Subject: Re: [OMPI users] Very slow MPI_GATHER
From: Jingcha Joba (pukkimonkey_at_[hidden])
Date: 2012-02-29 13:44:40


two things:
1. Too many mpi processes on one node leading to processes pre-empting each
other
2. Contention in your network.

On Wed, Feb 29, 2012 at 8:01 AM, Pinero, Pedro_jose <
Pedro_jose.Pinero_at_[hidden]> wrote:

> Hi,****
>
> ** **
>
> I am using OMPI v.1.5.5 to communicate 200 Processes in a 2-Computers
> cluster connected though Ethernet, obtaining a very poor performance. I
> have measured each operation time and I haver realised that the MPI_Gather
> operation takes about 1 second in each synchronization (only an integer is
> send in each case). Is this time range normal or I have a synchronization
> problem? Is there any way to improve this performance?****
>
> ** **
>
> Thank you for your help in advance****
>
> ** **
>
> Pedro****
>
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