[QE-users] npool
Ye Luo
xw111luoye at gmail.com
Wed Jan 6 00:40:07 CET 2021
I think that the statement "npools must be a divisor of the total number of
k-points" in the slides is inaccurate.
npools needs to be less than or equal to the total number of k-points
because every pool must have at least 1 k-point to work on.
npool not being a divisor doesn't cause a correctness issue.
A non-divisor causes more imbalance and reduces efficiency because some
pools work on less number of k-points and become idle at pool
synchronization points once their assigned k-points are completed.
In practice, the workload of each k-point differs, even if npool is a
divisor, there is additional imbalance in the calculation.
So select npool as a divisor is a recommendation for getting better
performance instead of a requirement.
Ye
===================
Ye Luo, Ph.D.
Computational Science Division & Leadership Computing Facility
Argonne National Laboratory
On Tue, Jan 5, 2021 at 5:16 PM Andrew Xu <andrewaccount at gmail.com> wrote:
> Hi users,
>
> Does npool need to divide the number of k-points after symmetry operations
> are performed? In a tutorial I saw online (
> https://materials.prace-ri.eu/497/7/QE__main_strategies_of_parallelization_and_levels_of_parallelisms.pdf):
> "By definition, npools must be a divisor of the total number of k-points."
>
> In a calculation I ran (relevant output below), I accidentally sent npool
> = 16, which does not divide the total number of k points after symmetry
> operations (35), but I got no errors. Am I misunderstanding something here?
>
> Best,
> Andrew
>
> ------------------------------
>
> Parallel version (MPI & OpenMP), running on 80 processor cores
> Number of MPI processes: 80
> Threads/MPI process: 1
> K-points division: npool = 16
> R & G space division: proc/nbgrp/npool/nimage = 5
> Reading input from pw_oncv_pbe0.in
>
> Current dimensions of program PWSCF are:
> Max number of different atomic species (ntypx) = 10
> Max number of k-points (npk) = 40000
> Max angular momentum in pseudopotentials (lmaxx) = 3
>
> IMPORTANT: XC functional enforced from input :
> Exchange-correlation = PBE0 ( 6 4 8 4 0 0)
> EXX-fraction = 0.25
> Any further DFT definition will be discarded
> Please, verify this is what you really want
>
>
> Subspace diagonalization in iterative solution of the eigenvalue
> problem:
> a serial algorithm will be used
>
> EXX: setup a grid of 512 q-points centered on each k-point
> (set verbosity='high' to see the list)
>
> Parallelization info
> --------------------
> sticks: dense smooth PW G-vecs: dense smooth PW
> Min 194 194 58 4548 4548 756
> Max 196 196 59 4550 4550 759
> Sum 973 973 293 22743 22743 3791
>
>
>
> bravais-lattice index = 1
> lattice parameter (alat) = 7.1240 a.u.
> unit-cell volume = 361.5528 (a.u.)^3
> number of atoms/cell = 4
> number of atomic types = 2
> number of electrons = 46.00
> number of Kohn-Sham states= 26
> kinetic-energy cutoff = 60.0000 Ry
> charge density cutoff = 240.0000 Ry
> cutoff for Fock operator = 240.0000 Ry
> convergence threshold = 1.0E-08
> mixing beta = 0.7000
> number of iterations used = 8 plain mixing
> Exchange-correlation = PBE0 ( 6 4 8 4 0 0)
> EXX-fraction = 0.25
> ...
>
> atomic species valence mass pseudopotential
> O 6.00 15.99940 O ( 1.00)
> W 28.00 183.85000 W ( 1.00)
>
> 48 Sym. Ops., with inversion, found
>
>
>
> Cartesian axes
>
> site n. atom positions (alat units)
> 1 W tau( 1) = ( 0.0000000 0.0000000 0.0000000
> )
> 2 O tau( 2) = ( 0.0000000 0.5000000 0.0000000
> )
> 3 O tau( 3) = ( 0.5000000 0.0000000 0.0000000
> )
> 4 O tau( 4) = ( 0.0000000 0.0000000 0.5000000
> )
>
> number of k points= 35
> cart. coord. in units 2pi/alat
> k( 1) = ( 0.0000000 0.0000000 0.0000000), wk = 0.0039062
> k( 2) = ( 0.0000000 0.0000000 0.1250000), wk = 0.0234375
> k( 3) = ( 0.0000000 0.0000000 0.2500000), wk = 0.0234375
> k( 4) = ( 0.0000000 0.0000000 0.3750000), wk = 0.0234375
> k( 5) = ( 0.0000000 0.0000000 -0.5000000), wk = 0.0117188
> k( 6) = ( 0.0000000 0.1250000 0.1250000), wk = 0.0468750
> k( 7) = ( 0.0000000 0.1250000 0.2500000), wk = 0.0937500
> k( 8) = ( 0.0000000 0.1250000 0.3750000), wk = 0.0937500
> k( 9) = ( 0.0000000 0.1250000 -0.5000000), wk = 0.0468750
> k( 10) = ( 0.0000000 0.2500000 0.2500000), wk = 0.0468750
> k( 11) = ( 0.0000000 0.2500000 0.3750000), wk = 0.0937500
> k( 12) = ( 0.0000000 0.2500000 -0.5000000), wk = 0.0468750
> k( 13) = ( 0.0000000 0.3750000 0.3750000), wk = 0.0468750
> k( 14) = ( 0.0000000 0.3750000 -0.5000000), wk = 0.0468750
> k( 15) = ( 0.0000000 -0.5000000 -0.5000000), wk = 0.0117188
> k( 16) = ( 0.1250000 0.1250000 0.1250000), wk = 0.0312500
> k( 17) = ( 0.1250000 0.1250000 0.2500000), wk = 0.0937500
> k( 18) = ( 0.1250000 0.1250000 0.3750000), wk = 0.0937500
> k( 19) = ( 0.1250000 0.1250000 -0.5000000), wk = 0.0468750
> k( 20) = ( 0.1250000 0.2500000 0.2500000), wk = 0.0937500
> k( 21) = ( 0.1250000 0.2500000 0.3750000), wk = 0.1875000
> k( 22) = ( 0.1250000 0.2500000 -0.5000000), wk = 0.0937500
> k( 23) = ( 0.1250000 0.3750000 0.3750000), wk = 0.0937500
> k( 24) = ( 0.1250000 0.3750000 -0.5000000), wk = 0.0937500
> k( 25) = ( 0.1250000 -0.5000000 -0.5000000), wk = 0.0234375
> k( 26) = ( 0.2500000 0.2500000 0.2500000), wk = 0.0312500
> k( 27) = ( 0.2500000 0.2500000 0.3750000), wk = 0.0937500
> k( 28) = ( 0.2500000 0.2500000 -0.5000000), wk = 0.0468750
> k( 29) = ( 0.2500000 0.3750000 0.3750000), wk = 0.0937500
> k( 30) = ( 0.2500000 0.3750000 -0.5000000), wk = 0.0937500
> k( 31) = ( 0.2500000 -0.5000000 -0.5000000), wk = 0.0234375
> k( 32) = ( 0.3750000 0.3750000 0.3750000), wk = 0.0312500
> k( 33) = ( 0.3750000 0.3750000 -0.5000000), wk = 0.0468750
> k( 34) = ( 0.3750000 -0.5000000 -0.5000000), wk = 0.0234375
> k( 35) = ( -0.5000000 -0.5000000 -0.5000000), wk = 0.0039062
>
> Dense grid: 22743 G-vectors FFT dimensions: ( 36, 36, 36)
>
> Estimated max dynamical RAM per process > 14760.85MB
>
> Estimated total allocated dynamical RAM > 1180867.90MB
> ....
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20210105/ad9d6e44/attachment.html>
More information about the users
mailing list