[Pw_forum] Parallel efficiency problem
Axel Kohlmeyer
akohlmey at cmm.chem.upenn.edu
Tue Jul 29 10:48:40 CEST 2008
On Tue, 29 Jul 2008, lihm wrote:
HL> Dear all,
dear haiming li,
HL> I am a fresh user of PWscf. I run the parallel calculations to have a test.
HL> A single process test is OK:
HL>
HL> PWSCF : 5m40.68s CPU time, 6m 0.14s wall time
HL>
HL> However, I found that the walltime is too long for parallel calculations:
HL>
HL> PWSCF : 1m 4.86s CPU time, 32m53.67s wall time
HL>
HL> I am sure that the CPU are not busy, or influenced by other jobs.
yes, but what kind of a network do you have?
please see the many discussions on efficient use
of paralellism in QE calculations in the QE documentation
(wiki!) and the mailing list archives.
HL> The running command is:
HL>
HL> /usr/local/mpich/bin/mpirun -np 4 -machinefile nodelist /bin/pw.x < ZnO.scf.inp > ZnO.scf.out
try adding -npools 4 after pw.x
your system is small but has many k-points. that flag should
enable parallelization over k-points which is less sensitive
to high communication latencies and slow networks.
the value of the 'disk_io' parameter can have an effect as well.
cheers,
axel.
HL> My input file is
HL>
HL> &CONTROL
HL> calculation = 'scf' ,
HL> restart_mode = 'from_scratch' ,
HL> outdir = './' ,
HL> wfcdir = '/tmp/' ,
HL> pseudo_dir = './' ,
HL> prefix = 'ZnO' ,
HL> disk_io = 'minimal' ,
HL> tstress = .true. ,
HL> tprnfor = .true. ,
HL> /
HL> &SYSTEM
HL> ibrav = 4,
HL> celldm(1) = 6.213,
HL> celldm(3) = 1.610,
HL> nat = 4,
HL> ntyp = 2,
HL> ecutwfc = 40 ,
HL> ecutrho = 400 ,
HL> /
HL> &ELECTRONS
HL> mixing_mode = 'plain' ,
HL> mixing_beta = 0.7 ,
HL> diagonalization = 'david' ,
HL> /
HL> ATOMIC_SPECIES
HL> Zn 65.39200 Zn.pbe-van.UPF
HL> O 16.00000 O.pbe-rrkjus.UPF
HL> ATOMIC_POSITIONS crystal
HL> Zn 0.666666667 0.333333333 0.000000000
HL> Zn 0.333333333 0.666666667 0.500000000
HL> O 0.666666667 0.333333333 0.380000000
HL> O 0.333333333 0.666666667 0.880000000
HL> K_POINTS automatic
HL> 16 16 8 0 0 0
HL>
HL> Can anyone help me to fix the problem? Thank you.
HL>
HL> Best wishes!
HL>
HL> Haiming Li
HL> 2008-07-29
HL>
HL> --------------
HL> Haiming Li
HL> Beijing Synchrotron Radiation Facility
HL> Institute of High Energy Physics
HL> Chinese Academy of Sciences
HL> 19 Yu Quan Lu, 100049 Beijing, P.R. China
HL> Tel: 0086+10 8823 6437 / 0086+135 8190 2824
HL> E-mail:lihm at ihep.ac.cn
HL>
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HL> Pw_forum at pwscf.org
HL> http://www.democritos.it/mailman/listinfo/pw_forum
HL>
--
=======================================================================
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.
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