[Nek5000-users] question about efficient running nek5000

[nek5000-users at lists.mcs.anl.gov]

Hi,

I ran nek5000 on 1024 CPUs which is divided to 128 nodes and 8 cores per
node, and the same problem on 1200 CPUs with 100 nodes and 12 cores per
node, however in second case I got lower efficiency, simulation goes slower
about 5~8 percent!! I ran both cases on the same cluster!! Does anyone have
any idea why I do not get higher efficiency with the higher number of CPUs
but less nodes involved!? Could memory be a limitation here or since
numbers in first case are power of 2, it is more efficient!?

Thanks,
Ami
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