[gmx-users] Performance in ia64 and x86_64

Ignacio Fernández Galván jellby at yahoo.com
Fri Feb 11 14:44:09 CET 2011

---- Original Message ----
From: Mark Abraham <Mark.Abraham at anu.edu.au>

> We can't say with the information given. For best performance, the number of
> threads cannot exceed the number of physical cores available to one processor.
> To go higher, you need to compile and use GROMACS with MPI, not threading. If
> the IA64 is "dual core" then you are not measuring anything useful. You also 
> to be sure you're measuring for a decent length of time - a few minutes at 

It seems the x86_64 processor has 4 cores and 8 threads support 
(<http://ark.intel.com/Product.aspx?id=37104>), so the machine has probably two 
physical processors. I thought MPI was only needed if there was network 
communication involved, as in a cluster, but not in SMP, which is what both 
machines are (single memory, single OS), I guess I was wrong. I'll try compiling 
with MPI.



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