[Pw_forum] Effective parallel implementation?

[Bang C. Huynh]

Dear all, 

I am currently attempting to perform several structural relaxation
calculations on supercells that contain at least ~70 atoms (and even
more, say hundreds). My calculations are being done on a single node
with 40 cores, 2.4 GHz, Intel Xeon E5-2676v3 and 160 GiB memory
(m4.10xlarge Amazon EC2). I am just wondering if my implementation for
parallelism is 'reasonable' in the sense that the resources are fully
utilised, and not in some way underutilised or poorly distributed. I'm
pretty new to this so I'm not sure what to expect... Should I be happy
with the current performance, can it be better, or should I consider
deploying more resources and is it worth it? Currently one scf iteration
takes around 5-7 minutes. Scf-convergence is achieved after around 50
scf iterations, and I'm not sure how long it's going to take for the
vc-relax iterations to converge... 

The input file is shown below. I use this command to initiate the job: 

> mpirun -np 40 pw.x -npool 2 -ndiag 36 < skutU0.125_vc.vc2 > skutU0.125_vc.vc2.out

Thank you for your help. 

Regards, 
-- 

BANG C. HUYNH
Peterhouse
University of Cambridge
CB2 1RD
The United Kingdom

========input======= 

> &CONTROL
> title = skutterudite-U-doped ,
> calculation = 'vc-relax' ,
> outdir = './' ,
> wfcdir = './' ,
> pseudo_dir = '../pseudo/' ,
> prefix = 'skutU0.125_vc' ,
> etot_conv_thr = 1.0D-5 ,
> forc_conv_thr = 1.95D-6 ,
> nstep = 250 ,
> dt = 150 ,
> /
> &SYSTEM
> ibrav = 6,
> celldm(1) = 17.06
> celldm(3) = 2,
> nat = 66,
> ntyp = 3,
> ecutwfc = 93 ,
> ecutrho = 707 ,
> occupations = 'smearing' ,
> starting_spin_angle = .false. ,
> degauss = 0.02 ,
> smearing = 'methfessel-paxton' ,
> /
> &ELECTRONS
> conv_thr = 1D-10 ,
> /
> &IONS
> /
> &CELL
> cell_dynamics = 'damp-w' ,
> cell_dofree = 'all' ,
> /
> ATOMIC_SPECIES
> Co 58.93000 Co.pz-nd-rrkjus.UPF 
> Sb 121.76000 Sb.pz-bhs.UPF 
> U 238.02891 U.pz-spfn-rrkjus_psl.1.0.0.UPF 
> ATOMIC_POSITIONS crystal 
> Co 0.250000000 0.250000000 0.125000000 0 0 0 
> Co 0.250000000 0.250000000 0.625000000 0 0 0 
> Co 0.750000000 0.750000000 0.375000000 0 0 0 
> Co 0.750000000 0.750000000 0.875000000 0 0 0 
> Co 0.750000000 0.750000000 0.125000000 0 0 0 
> Co 0.750000000 0.750000000 0.625000000 0 0 0 
> Co 0.250000000 0.250000000 0.375000000 0 0 0 
> Co 0.250000000 0.250000000 0.875000000 0 0 0 
> Co 0.750000000 0.250000000 0.375000000 0 0 0 
> Co 0.750000000 0.250000000 0.875000000 0 0 0 
> Co 0.250000000 0.750000000 0.125000000 0 0 0 
> Co 0.250000000 0.750000000 0.625000000 0 0 0 
> Co 0.250000000 0.750000000 0.375000000 0 0 0 
> Co 0.250000000 0.750000000 0.875000000 0 0 0 
> Co 0.750000000 0.250000000 0.125000000 0 0 0 
> Co 0.750000000 0.250000000 0.625000000 0 0 0 
> Sb 0.000000000 0.337592989 0.078553498 
> Sb 0.000000000 0.337592989 0.578553498 
> Sb 0.000000000 0.662407041 0.421446502 
> Sb 0.000000000 0.662407041 0.921446502 
> Sb 0.000000000 0.662407041 0.078553498 
> Sb 0.000000000 0.662407041 0.578553498 
> Sb 0.000000000 0.337592989 0.421446502 
> Sb 0.000000000 0.337592989 0.921446502 
> Sb 0.157106996 0.000000000 0.168796495 
> Sb 0.157106996 0.000000000 0.668796480 
> Sb 0.842893004 0.000000000 0.331203520 
> Sb 0.842893004 0.000000000 0.831203520 
> Sb 0.157106996 0.000000000 0.331203520 
> Sb 0.157106996 0.000000000 0.831203520 
> Sb 0.842893004 0.000000000 0.168796495 
> Sb 0.842893004 0.000000000 0.668796480 
> Sb 0.337592989 0.157106996 0.000000000 
> Sb 0.337592989 0.157106996 0.500000000 
> Sb 0.662407041 0.842893004 0.000000000 
> Sb 0.662407041 0.842893004 0.500000000 
> Sb 0.662407041 0.157106996 0.000000000 
> Sb 0.662407041 0.157106996 0.500000000 
> Sb 0.337592989 0.842893004 0.000000000 
> Sb 0.337592989 0.842893004 0.500000000 
> Sb 0.500000000 0.837592959 0.328553498 
> Sb 0.500000000 0.837592959 0.828553498 
> Sb 0.500000000 0.162407011 0.171446502 
> Sb 0.500000000 0.162407011 0.671446502 
> Sb 0.500000000 0.162407011 0.328553498 
> Sb 0.500000000 0.162407011 0.828553498 
> Sb 0.500000000 0.837592959 0.171446502 
> Sb 0.500000000 0.837592959 0.671446502 
> Sb 0.657106996 0.500000000 0.418796480 
> Sb 0.657106996 0.500000000 0.918796480 
> Sb 0.342893004 0.500000000 0.081203505 
> Sb 0.342893004 0.500000000 0.581203520 
> Sb 0.657106996 0.500000000 0.081203505 
> Sb 0.657106996 0.500000000 0.581203520 
> Sb 0.342893004 0.500000000 0.418796480 
> Sb 0.342893004 0.500000000 0.918796480 
> Sb 0.837592959 0.657106996 0.250000000 
> Sb 0.837592959 0.657106996 0.750000000 
> Sb 0.162407011 0.342893004 0.250000000 
> Sb 0.162407011 0.342893004 0.750000000 
> Sb 0.162407011 0.657106996 0.250000000 
> Sb 0.162407011 0.657106996 0.750000000 
> Sb 0.837592959 0.342893004 0.250000000 
> Sb 0.837592959 0.342893004 0.750000000 
> U 0.000000000 0.000000000 0.000000000 
> U 0.000000000 0.000000000 0.500000000 
> K_POINTS automatic 
> 4 4 2 0 0 0
 
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