[gmx-users] Re: gmx-users Digest, Vol 2, Issue 41

Pim Schravendijk schraven at mpip-mainz.mpg.de
Thu Jun 17 12:20:02 CEST 2004

Dear Damodaran,

When I run a process without MPI it just runs on one processor, I don't 
find it to be shared, although I didn't manage to get top showing me the 
per processor load anyway (I am not that happy with macosx's top). 
If I start a second instance of mdrun, it will reside on the other 
processor, I get good performance with my non-MPI install.

If you find too slow results you might have not enable the altivec loops.
Use the:

setenv CFLAGS "-O3 -faltivec"

setting to get full profit from your mac! 

Greetings, Pim

Pim Schravendijk - PhD Student
Max Planck Institute for Polymer Research

> ------------------------------
> Message: 2
> Date: Wed, 16 Jun 2004 23:16:13 -0400 (EDT)
> From: "Damodaran Krishnan" <damodak at muohio.edu>
> Dear gmx users,
>    Do I need LAM/MPI for a dual processor G5, to use both the processors?
> The operating system's scheduling software will give the job to the
> processor doing less work at any given time. So any job is shared by
> both the processors right ?
>    I compiled GROMACS without LAM/MPI and when I run it, I find both the
> processors of G5 are being used. But in the end I find the calculation
> is really slow.

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