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Subject: [OMPI users] Sandy Bridge performance question
From: Blosch, Edwin L (edwin.l.blosch_at_[hidden])
Date: 2013-06-06 19:10:07


I am running single-node Sandy Bridge cases with OpenMPI and looking at scaling.

I'm using -bind-to-core without any other options (default is -bycore I believe).

These numbers indicate number of cores first, then the second digit is the run number (except for n=1, all runs repeated 3 times). Any thought why n15 should be so much slower than n16? I also measure the RSS of the running processes, and the rank 0 process for n=15 cases uses about 2x more memory than all the other ranks, whereas all the ranks use the same amount of memory for the n=16 cases.

Thanks for insights,

Ed

n1.1: 6.9530
n2.1: 7.0185
n2.2: 7.0313
n3.1: 8.2069
n3.2: 8.1628
n3.3: 8.1311
n4.1: 7.5307
n4.2: 7.5323
n4.3: 7.5858
n5.1: 9.5693
n5.2: 9.5104
n5.3: 9.4821
n6.1: 8.9821
n6.2: 8.9720
n6.3: 8.9541
n7.1: 10.640
n7.2: 10.650
n7.3: 10.638
n8.1: 8.6822
n8.2: 8.6630
n8.3: 8.6903
n9.1: 9.5058
n9.2: 9.5255
n9.3: 9.4809
n10.1: 10.484
n10.2: 10.452
n10.3: 10.516
n11.1: 11.327
n11.2: 11.316
n11.3: 11.318
n12.1: 12.285
n12.2: 12.303
n12.3: 12.272
n13.1: 13.127
n13.2: 13.113
n13.3: 13.113
n14.1: 14.035
n14.2: 13.989
n14.3: 14.021
n15.1: 14.533
n15.2: 14.529
n15.3: 14.586
n16.1: 8.6542
n16.2: 8.6731
n16.3: 8.6586
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