On Tue, 6 May 2008, Eduardo Ariel Menendez Proupin wrote: EAMP> Dear Axel, EAMP> EAMP> > you should also compare against the parallel executable EAMP> > run with -np 1 against the serial executable. EAMP> EAMP> It is a bit slower.
eduardo, ok. thanks, here are some timing results on my desktop. the machine was not entirely idle and freshly booted, so take the numbers with a bit of caution. i have a one year old two-socket intel dual core 2.66GHz machine (i.e. more or less equivalent to a single socket intel quad-core, with two dual-core dies in one case). this is using the latest cvs code: with serial MKL, serial FFTW-2.1.5 and OpenMPI with 4 mpi tasks. i get a wall time of 12m12s and cpu time of 10m40s. changing MKL to threaded MKL using 4 threads and 1 mpi task i get a wall time of 18m8s and cpu time of 28m30s (which means that roughly 40% of the time the code was running multi-threaded BLAS/LAPACK). with serial FFT, threaded MKL using 2 threads and 2 mpi tasks i get a wall time of 12m45s and cpu time of 14.42s now when i swap the serial FFTW2 against the intel MKL FFTW2 wrapper i get with 2 threads and 2 MPI tasks a wall time of 15m2s and a cpu time of 24m11s. and with 4 threads and 1 MPI task i get a wall time of 0h19m and a cpu time of 1h 2m and finally when disabling threading and with 4 MPI tasks i get 12m38 wall time and 11m14s cpu time. obviously, switching to the intel fft didn't help. your system with many states and only gamma point is definitely a case that benefits the most from multi-threaded BLAS/LAPACK. i'm curious to learn how these number match up with your performance measurements. cheers, axel. EAMP> EAMP> Attached is my input. EAMP> EAMP> EAMP> EAMP> -- ======================================================================= Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu http://www.cmm.upenn.edu Center for Molecular Modeling -- University of Pennsylvania Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323 tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425 ======================================================================= If you make something idiot-proof, the universe creates a better idiot.
