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Subject: Re: [OMPI users] poor performance using the openib btl
From: Fischer, Greg A. (fischega_at_[hidden])
Date: 2014-06-25 10:52:36


I looked through my configure log, and that option is not enabled. Thanks for the suggestion.

From: users [mailto:users-bounces_at_[hidden]] On Behalf Of Maxime Boissonneault
Sent: Wednesday, June 25, 2014 10:51 AM
To: Open MPI Users
Subject: Re: [OMPI users] poor performance using the openib btl

Hi,
I recovered the name of the option that caused problems for us. It is --enable-mpi-thread-multiple

This option enables threading within OPAL, which was bugged (at least in 1.6.x series). I don't know if it has been fixed in 1.8 series.

I do not see your configure line in the attached file, to see if it was enabled or not.

Maxime

Le 2014-06-25 10:46, Fischer, Greg A. a écrit :
Attached are the results of "grep thread" on my configure output. There appears to be some amount of threading, but is there anything I should look for in particular?

I see Mike Dubman's questions on the mailing list website, but his message didn't appear to make it to my inbox. The answers to his questions are:

[binford:fischega] $ rpm -qa | grep ofed
ofed-doc-1.5.4.1-0.11.5
ofed-kmp-default-1.5.4.1_3.0.76_0.11-0.11.5
ofed-1.5.4.1-0.11.5

Distro: SLES11 SP3

HCA:
[binf102:fischega] $ /usr/sbin/ibstat
CA 'mlx4_0'
        CA type: MT26428

Command line (path and LD_LIBRARY_PATH are set correctly):
mpirun -x LD_LIBRARY_PATH -mca btl openib,sm,self -mca btl_openib_verbose 1 -np 31 $CTF_EXEC

From: users [mailto:users-bounces_at_[hidden]] On Behalf Of Maxime Boissonneault
Sent: Tuesday, June 24, 2014 6:41 PM
To: Open MPI Users
Subject: Re: [OMPI users] poor performance using the openib btl

What are your threading options for OpenMPI (when it was built) ?

I have seen OpenIB BTL completely lock when some level of threading is enabled before.

Maxime Boissonneault

Le 2014-06-24 18:18, Fischer, Greg A. a écrit :
Hello openmpi-users,

A few weeks ago, I posted to the list about difficulties I was having getting openib to work with Torque (see "openib segfaults with Torque", June 6, 2014). The issues were related to Torque imposing restrictive limits on locked memory, and have since been resolved.

However, now that I've had some time to test the applications, I'm seeing abysmal performance over the openib layer. Applications run with the tcp btl execute about 10x faster than with the openib btl. Clearly something still isn't quite right.

I tried running with "-mca btl_openib_verbose 1", but didn't see anything resembling a smoking gun. How should I go about determining the source of the problem? (This uses the same OpenMPI Version 1.8.1 / SLES11 SP3 / GCC 4.8.3 setup discussed previously.)

Thanks,
Greg

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---------------------------------
Maxime Boissonneault
Analyste de calcul - Calcul Québec, Université Laval
Ph. D. en physique
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Maxime Boissonneault
Analyste de calcul - Calcul Québec, Université Laval
Ph. D. en physique