Regarding FFTW routines usage in NAMD

From: Puneet Singh (
Date: Tue Oct 20 2015 - 07:39:50 CDT

Dear Sir,
I am trying to build namd with fftw , i have multiple version of fftw at
different locations . So to check which version of fftw my namd2 binary
refers i did *ldd namd2* : => (0x00007fff7f2ff000) => /lib64/ (0x0000003a1cc00000) => /home/puneet/NAMD_BUILD/common_dependencies/lib/ (0x00002b1785241000) => /lib64/ (0x0000003a1c800000) => /opt/intel//impi/ (0x00002b17855c4000) => /opt/intel//impi/ (0x00002b17857e4000) => /opt/intel//impi/
(0x00002b1785a70000) => /lib64/ (0x0000003a1d400000) => /lib64/ (0x0000003a1c400000) => /usr/lib64/ (0x0000003a28400000) => /lib64/ (0x0000003a27000000) => /lib64/ (0x0000003a1c000000)
    /lib64/ (0x0000003a1bc00000) =>
(0x00002b17861a3000) =>
(0x00002b178665e000) =>
(0x00002b17872ad000) =>

fftw is not there in the dependency list & running this namd2 binary
against apoa1 example with 500 steps (23 processes on 24 cores) finishes in
36 seconds without fftw routines!

So i wish to know weather the namd2 binary needs fftw library ? I have
doubts that i may not have configured properly ,The following command i am
using to configure namd2:

./*config* mpi-linux-x86_64-MPI --charm-arch mpi-linux-x86_64-ifort-mpicxx
--with-fftw --fftw-prefix $ROOT_DIR/common_dependencies --cxx icpc --cc
icc --cc-opts --with-tcl --tcl-prefix $ROOT_DIR/common_dependencies

I will be benchmarking against apoa1 example ,so, does solving against this
input file needs fftw routines or can fftw routines improve namd
performance (36 seconds) ?

Eagerly Awaiting your reply,

Thanks & Regards,
Puneet Singh

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