[gmx-users] Parallel FFTW performance

[Bing Kim]

Hi All!

I am sorry this question is not for Gromacs exactly but for FFTW.
But this question would raise on Gramacs too.
I recently installed FFTW-2.1.5 which can use MPI.
It was compiled with gcc-3.3.2 and mpich-1.2.5.2.
When I ran a benchmark test program, rfftw_mpi_test, which is located in 
fftw-2.1.5/mpi,
I found that its performace is worse in dual cpus than single cpu.
Basically, communication cost should be zero in SMP machine.. that I 
expected.
So.. I wonder if gromacs use rfftw_mpi, how it can get speed up in multiple 
processors.
Please help me understand this thing.

Bing Kim

_________________________________________________________________
Never get a busy signal because you are always connected  with high-speed 
Internet access. Click here to comparison-shop providers.  
https://broadband.msn.com