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Subject: Re: [OMPI users] EXTERNAL: Re: Need advice on performance problem
From: Blosch, Edwin L (edwin.l.blosch_at_[hidden])
Date: 2013-06-09 19:31:40


Correct. 20 nodes, 8 cores per dual-socket on each node = 360.

From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On Behalf Of Ralph Castain
Sent: Sunday, June 09, 2013 6:18 PM
To: Open MPI Users
Subject: Re: [OMPI users] EXTERNAL: Re: Need advice on performance problem

So, just to be sure - when you run 320 "cores", you are running across 20 nodes?

Just want to ensure we are using "core" the same way - some people confuse cores with hyperthreads.

On Jun 9, 2013, at 3:50 PM, "Blosch, Edwin L" <edwin.l.blosch_at_[hidden]<mailto:edwin.l.blosch_at_[hidden]>> wrote:

16. dual-socket Xeon, E5-2670.

I am trying a larger model to see if the performance drop-off happens at a different number of cores.
Also I'm running some intermediate core-count sizes to refine the curve a bit.
I also added mpi_show_mca_params all, and at the same time, btl_openib_use_eager_rdma 1, just to see if that does anything.

From: users-bounces_at_[hidden]<mailto:users-bounces_at_[hidden]> [mailto:users-bounces_at_[hidden]<mailto:bounces_at_[hidden]>] On Behalf Of Ralph Castain
Sent: Sunday, June 09, 2013 5:04 PM
To: Open MPI Users
Subject: EXTERNAL: Re: [OMPI users] Need advice on performance problem

Looks to me like things are okay thru 160, and then things fall apart after that point. How many cores are on a node?

On Jun 9, 2013, at 1:59 PM, "Blosch, Edwin L" <edwin.l.blosch_at_[hidden]<mailto:edwin.l.blosch_at_[hidden]>> wrote:

I'm having some trouble getting good scaling with OpenMPI 1.6.4 and I don't know where to start looking. This is an Infiniband FDR network with Sandy Bridge nodes. I am using affinity (--bind-to-core) but no other options. As the number of cores goes up, the message sizes are typically going down. There seem to be lots of options in the FAQ, and I would welcome any advice on where to start. All these timings are on a completely empty system except for me.

Thanks

    MPI # cores Ave. Rate Std. Dev. % # timings Speedup Efficiency
================================================================================================
MVAPICH | 16 | 8.6783 | 0.995 % | 2 | 16.000 | 1.0000
MVAPICH | 48 | 8.7665 | 1.937 % | 3 | 47.517 | 0.9899
MVAPICH | 80 | 8.8900 | 2.291 % | 3 | 78.095 | 0.9762
MVAPICH | 160 | 8.9897 | 2.409 % | 3 | 154.457 | 0.9654
MVAPICH | 320 | 8.9780 | 2.801 % | 3 | 309.317 | 0.9666
MVAPICH | 480 | 8.9704 | 2.316 % | 3 | 464.366 | 0.9674
MVAPICH | 640 | 9.0792 | 1.138 % | 3 | 611.739 | 0.9558
MVAPICH | 720 | 9.1328 | 1.052 % | 3 | 684.162 | 0.9502
MVAPICH | 800 | 9.1945 | 0.773 % | 3 | 755.079 | 0.9438
OpenMPI | 16 | 8.6743 | 2.335 % | 2 | 16.000 | 1.0000
OpenMPI | 48 | 8.7826 | 1.605 % | 2 | 47.408 | 0.9877
OpenMPI | 80 | 8.8861 | 0.120 % | 2 | 78.093 | 0.9762
OpenMPI | 160 | 8.9774 | 0.785 % | 2 | 154.598 | 0.9662
OpenMPI | 320 | 12.0585 | 16.950 % | 2 | 230.191 | 0.7193
OpenMPI | 480 | 14.8330 | 1.300 % | 2 | 280.701 | 0.5848
OpenMPI | 640 | 17.1723 | 2.577 % | 3 | 323.283 | 0.5051
OpenMPI | 720 | 18.2153 | 2.798 % | 3 | 342.868 | 0.4762
OpenMPI | 800 | 19.3603 | 2.254 % | 3 | 358.434 | 0.4480
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