On Friday 09 July 2010, Andreas Schäfer wrote: > Thanks, those were good suggestions. > > On 11:53 Fri 09 Jul , Peter Kjellstrom wrote: > > On an E5520 (nehalem) node I get ~5 GB/s ping-pong for >64K sizes. > > I just tried a Core i7 system which maxes at 6550 MB/s for the > ping-pong test.
It makes quite some difference if the ranks end up on the same socket or different sockets (on an i7 you only have one). > > On QDR IB on similar nodes I get ~3 GB/s ping-pong for >256K. > > I'll try to find a Intel system to repeat the tests. Maybe it's AMD's > different memory subsystem/cache architecture which is slowing Open > MPI? Or are my systems just badly configured? 8x pci-express gen2 5GT/s should show figures like mine. If it's pci-express gen1 or gen2 2.5GT/s or 4x or if the IB only came up with two lanes then 1500 is expected. /Peter
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