Do you have CPU affinity enabled? Is this omp + MPI? Which compilers and flags. Give more details about the software stack
Original Message From: Jon Tegner Sent: Sunday, February 28, 2016 22:28 To: [email protected] Subject: [Beowulf] Scaling issues on Xeon E5-2680 Hi, have issues with performance on E5-2680. Each of the nodes have 2 of these 12 core CPUs on SuperMicro SuperServer 1028R-WMR (i.e., 24 cores on each node). For one of our applications (CFD/OpenFOAM) we have noticed that the calculation runs faster using 12 cores on 4 nodes compared to when using 24 cores on 4 nodes. In our environment we also have older AMD hardware (nodes with 4 CPUs with 12 cores each), and here we don't see these strange scaling issues. System is CentOS-7, and communication is over FDR Infiniband. BIOS is recently updated, and hyperthreading is disabled. Feel a bit lost here, and any hints on how to proceed with this are greatly appreciated! Thanks, /jon _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
