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Subject: Re: [OMPI users] 50% performance reduction due to OpenMPI v 1.3.2 forcing all MPI traffic over Ethernet instead of using Infiniband
From: Jim Kress (jimkress_58_at_[hidden])
Date: 2009-06-23 14:35:35


I assume you a referring to the openmpi-mca-params.conf file

As I indicated previously, my first run was with the line

btl=self,openib

As the only entry in the openmpi-mca-params.conf file. This my default
setting and was what I used, and it worked well, for v 1.2.8

Then I tried

btl=self,openib
mpi_yield_when_idle=0

As the only entries in the openmpi-mca-params.conf file. No difference in
the results.

Then I tried

btl=self,openib
mpi_yield_when_idle=0

As the only entries in the openmpi-mca-params.conf file and also set the
environment variable OMPI_MCA_mpi_leave_pinned=0
No difference in the results.

What else can I provide?

By the way, did you read the message where I retracted my assumption about
MPI traffic being forced over Ethernet?

Jim

> -----Original Message-----
> From: users-bounces_at_[hidden]
> [mailto:users-bounces_at_[hidden]] On Behalf Of Pavel Shamis (Pasha)
> Sent: Tuesday, June 23, 2009 7:24 AM
> To: Open MPI Users
> Subject: Re: [OMPI users] 50% performance reduction due to
> OpenMPI v 1.3.2 forcing all MPI traffic over Ethernet instead
> of using Infiniband
>
> Jim,
> Can you please share with us you mca conf file.
>
> Pasha.
> Jim Kress ORG wrote:
> > For the app I am using, ORCA (a Quantum Chemistry program), when it
> > was compiled using openMPI 1.2.8 and run under 1.2.8 with the
> > following in the openmpi-mca-params.conf file:
> >
> > btl=self,openib
> >
> > the app ran fine with no traffic over my Ethernet network and all
> > traffic over my Infiniband network.
> >
> > However, now that ORCA has been recompiled with openMPI
> v1.3.2 and run
> > under 1.3.2 (using the same openmpi-mca-params.conf file), the
> > performance has been reduced by 50% and all the MPI traffic
> is going
> > over the Ethernet network.
> >
> > As a matter of fact, the openMPI v1.3.2 performance now
> looks exactly
> > like the performance I get if I use MPICH 1.2.7.
> >
> > Anyone have any ideas:
> >
> > 1) How could this have happened?
> >
> > 2) How can I fix it?
> >
> > a 50% reduction in performance is just not acceptable. Ideas/
> > suggestions would be appreciated.
> >
> > Jim
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
>
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