The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Rick,

On 07 Sep 2007, at 21:49, Rick Muller wrote:

I'm trying to run a 48 atom job in parallel with abinit. There is

only one k-point, and no spin polarization. I've been through the

abinip tutorial, and have found very little effect using the band

parallelization, despite having 70 bands (I only got something like a

1.4 speedup on 4 processors). I've heard rumors of the FFT

parallelization: is this ready for production use, or should I just

learn to love serial jobs?

These are not rumours, have a look at the release_notes of both v5.3 (B.2) 

and v5.4 (B.4)

http://www.abinit.org/Infos_v5.3/release_notes/release_notes.html

http://www.abinit.org/Infos_v5.4/release_notes/release_notes.html

I think it is worth to try combined band/FFT parallelization

with ABINITv5.4 . There have been several exchanges of mails

on the Forum mailing list about it, you should search in the archives

for the names Francois Bottin and Gilles Zerah, who have 

actually submitted a paper, also available on 

http://www.arxiv.org/abs/0707.3405 . Abstract attached.

You might perhaps encounter difficulties in the make or link

steps of the installation, and it has not yet been as extensively

tested as the k point parallelization, but it is worth to give it a try now.

Xavier

Large scale ab initio calculations based on three levels of parallelization

Authors: François Bottin, Stéphane Leroux, Andrew Knyazev, Gilles Zérah

We suggest and implement a parallelization scheme based on an efficient multiband eigenvalue solver, called the locally optimal block preconditioned conjugate gradient LOBPCG method, and using an optimized three-dimensional (3D) fast Fourier transform (FFT) in the ab initio}plane-wave code ABINIT. In addition to the standard data partitioning over processors corresponding to different k-points, we introduce data partitioning with respect to blocks of bands as well as spatial partitioning in the Fourier space of coefficients over the plane waves basis set used in ABINIT. This k-points-multiband-FFT parallelization avoids any collective communications on the whole set of processors relying instead on one-dimensional communications only. For a single k-point, super-linear scaling is achieved for up to 100 processors due to an extensive use of hardware optimized BLAS, LAPACK, and SCALAPACK routines, mainly in the LOBPCG routine. We observe good performance up to 200 processors. With 10 k-points our three-way data partitioning results in linear scaling up to 1000 processors for a practical system used for testing.