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[BOTTIN Francois <francois.bottin@cea.fr>]

Hi Zeila,

Zeila Zanolli a écrit :
> the mpw values in the serial and parallel output files are different:
> serial: mpw = 30332
> 7cpu:  mpw =   4333 
> where mpw is the maximum number of plane waves.
> Hence it seems that the parallelization is done on the plane waves 
> (and indeed is  30332./7 ~ 4333 )
> However, in the input file it is   npfft = 1, that is no 
> parallelization on the plane waves.
> So... on what is actually performed the parallelization?
- mpw is the maximum number of PW you have on the processor 0.
As you have seen, this number is not connected to npfft (=1) but to 
npfft*npband (=7).
Indeed, in Abinit with paral_kgb=1, there are two distributions,
the "plane-wave" and the "band/FFT" ones, which are used in turn.
In the first one, the PW are distributed over the two "band and FFT 
levels" (npfft*npband).
In the second one, the bands are distributed over the "band level" (npband)
and their PW coefficients over the "FFT level" (npfft).
The code go from the first one to the second one by performing a 
communication
along the band level (see the article and/or the Abinit workshop pdf for 
more details).
So don't panic, mpw is well defined.

- Concerning the proposition of Emmanuel Arras, you can also put npkpt=2
using paral_kgb=1, in order to parallelize over spin components.

- As you already said, I haven't see any significant difference between 
your input and output files.

- This point has no relation with your problem but with abinit6.0 you can
use wfoptalg 14 and remove nloalg 4 from your input. It should improve 
the performance.

Let me know if you obtain some good (or bad) results from your timing 
analysis.
Good continuation,
Francois

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Francois Bottin                    tel: 01 69 26 41 73
CEA/DIF                            fax: 01 69 26 70 77
BP 12 Bruyeres-le-Chatel         email: Francois.Bottin@cea.fr
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