The ABINIT Users Mailing List ( CLOSED )

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

Hi Zeila,

This is a very strange behaviour. Never seen until now.
No luck! after a memory problem you have a scaling problem ;)
Is it possible that a relation exists between them (a swap problem due 
to a too large memory use)?

I don't see anything in your input file which can lead to this very poor 
scaling!
However, the input file is truncated. Please, would you send your whole 
input file,
and also the two output files, in order to see the diff between them.
Indeed, there are a lot of variables which can differ between the two 
calculations
(istwfk, nstep during one Broyden, printing,...)

You can also compare the various part of the timing between the 
sequential and parallel calculations.
If the part scales linearly, the timing is identical.
This could be useful to detect the one(s) which doesn't scale.
Note that you have to set timopt -3 to have a full description of the 
timing in parallel.
To have these results more quickly, you can also launch your sequential 
and parallel calculations
for 1 hour (or 2 Broyden steps).

Regards,
Francois

NB: What is the version of Abinit?

Zeila Zanolli a écrit :
> Dear all,
>
> I'm trying my luck with the relaxation of a ~60 atoms molecule with 
> abinit with PAW.
> I've set-up a calculation in serial mode and one in parallel mode, 
> using the band/fft parallelization.
> However, the parallel calculation is taking the same time as the 
> serial one, as you can see here:
>
> serial:    63 broyden steps in 41 hours
> 7 cpus:  64 broyden steps in 40 hours
>
> I've set the parallel flags using the paral_kgp = -n 
>
> I have also have a spin-polarized system and in this case the parallel 
> calculation was not proceeding at all:
> the calculation stopped at the broyden step 0, after the 3^rd iteration.
> The serial calculation for the same spin-pol system is, instead, 
> proceeding without problems (ok - it is just extremely slow: 19 
> broyden steps in ~ 40 hours).
>
>
> Here are my input files:
>
>
> #--------------- for the parallel calculation ---------------------
> paral_kgb 1
> npkpt  1
> npband 7       
> npfft  1  
> bandpp 4
> nband 112
> wfoptalg 4  nloalg 4  fftalg 401  intxc 0  fft_opt_lob 2
>
> #-------------- the following is the same in the parallel and serial 
> calculation ------
>
> kptopt 1
> ngkpt 1 1 1
> nshiftk 1
> shiftk 0 0 0
>
> ntime 1000
> tolmxf 1.e-5
> ionmov 2
>
> tolrff 1.e-2
> ixc 1
>
> ecut 20
> pawecutdg 40
> nstep 100
> diemac 1
>
>
>
> Same input for the spin-polarized case, just with the 'spin' variables 
> in addition:
> nsppol 2
> and initialization of the spin.
>
>
>
> Any help is appreciated!
> Thanks,
>     Zeila
>
>
>
>
> ---------------------------------------------------------------------------------------------
> Dr. Zeila Zanolli
>
> Université Catholique de Louvain (UCL)
> Unité Physico-Chimie et de Physique des Matériaux (PCPM) 
> Place Croix du Sud, 1 (Boltzmann)
> B-1348 Louvain-la-Neuve, Belgium
> Phone: +32 (0)10 47 3501 
> Mobile: +32 (0)487 556699
> Fax: +32 (0)10 47 3452
> e-mail: zeila.zanolli@uclouvain.be <mailto:zeila.zanolli@uclouvain.be>
> web: http://www.nano2hybrids.net/
> ---------------------------------------------------------------------------------------------


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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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