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From: Christopher D. Maestas (cdmaest_at_[hidden])
Date: 2007-06-06 13:09:10


George,

Apologies for not saying what latency is with Open MPI. I've noted it below.
I don't know why turning off the sm feature would help launching 1ppn. I just
tried turning it off and it didn't make a difference.

-cdm

On Wed, 6 Jun 2007, George Bosilca wrote:

> Which one is the latency with Open MPI ? Which version of Open MPI ?
>
> You might want to use OMPI_MCA_btl=mx,self to see if it makes any
> difference.
>
> Thanks,
> george.
>
> On Jun 6, 2007, at 12:26 PM, Maestas, Christopher Daniel wrote:
>
>> With 2 nodes using 1.1.7 with the patch we measured (using mpich-mx
>> 1.2.7..4):
>> 3.07us
>>

Open MPI 1.2.2
>> With mx 1.2.1-rc18 we measure:
>> 3.69 us

>> And with mpich-mx 1.2.7..4 we see:
>> 3.20us
>>
>> Our Open MPI settings:
>> ---
>> # env | grep OMPI
>> OMPI_MCA_pml=cm
>> OMPI_MCA_mpi_keep_hostnames=1
>> OMPI_MCA_oob_tcp_include=eth0
>> OMPI_MCA_btl=mx,sm,self
>>
>> Does anyone know why the latency would be slightly higher using
>> Open MPI
>> versus MPICH-MX?
>>
>> Thanks,
>> -cdm
>>
>>
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>
>