[Pw_forum] Calculation Precision on QE5.0.2-GPU

[Filippo Spiga]

Dear Tobin,

you problem is not new, other people (in China) pointed to me about it. So the issue you see it is 99% due to a possible bug in ADDUSDENS. I have been able to reproduce it locally on my cluster.  Please ad the flag "-D__DISABLE_CUDA_ADDUSDENS" to make.sys, it will make the issue disappear. I am investigating during these days to find a fix and I will commit it as fast as I can.

The ML list for QE-GPU is q-e-gpgpu at qe-forge.org Please send there any queries concerning the package, I rarely follow what is posted on the main PWscf mailing-list.

Good luck for the competition
F


On Feb 21, 2014, at 3:56 AM, Tobin Chen <chenzhao.me at gmail.com> wrote:
> hi everyone:
>     It's my first time to use QE, and I meet some problems that I don't know how to handle it.
>     DESCRIPTION
>     At first, I compile the QE5.0.2 without GPU. And I use pw.x to run my relax.in(attach at the end), using the command:
>         [PATH_TO_QE]/bin/pw.x -in relax.in
>     By this version, I can run relax.in to the end.
>     However, when I recompile QE with Nvidia GPU (QE-GPU-r216.tar.gz with the QE-5.0.2_GPU-r216.patch, and I use CUDA5.5), I meet the one of the Frequent errors during execution, which is 
>         %%%%%%%
>             Error in routine electrons (1):
>             charge is wrong
>         %%%%%%%
>     So I change the input file by comment some settings on SYSTEM modules.
>         !  occupations='smearing',smearing='gaussian',degauss=0.002,
>         !  nspin=2
>     And then I can run it on my gpu host, using my gpu card. For this situation, I guess the "gaussian smearing" may lost some precision on GPU calculation. But I'm not sure that.
> 
>     QUESTION
>     I feel confused of this situation. My question is
>     1, Is the GPU's precision not support for  some of the QE workload? or just some algorithms?
>     2, If it's just for the algorithms problem, which algorithm would be affect during calculating on GPU version? How should I do when I want to use GPU to accelera the QE-CPU version?
>     3, The last question is, what changes would happen to the final result when I modify the parameter "occupations" and "smearing"? Just like the PW/tests/check-pw.x.j, if I don't have the reference, How can I check whether my result is true when I calculate for the new workload?
> 
>     Thanks for everyone ! Maybe my chinglish would confuse you, but please report it to me. Because I really want you help !
>     Thank you very much !
> 
> -- 
> Tobin Chen
> Sun Yat-Sen University, Guangdong, China.
> 
> file relax.in
> &control
>    calculation = 'vc-relax'
>    prefix='Na2Fe2As2O',
>    pseudo_dir ='/home/jin/projects/asc14/suanli/test2/workload1/workload2-upf'
>    outdir='./tmp'
>         etot_conv_thr = 1.0E-5 ,
>         forc_conv_thr = 1.0D-4
>    tprnfor=.TRUE.
>    disk_io='none'
> /
> &system
>    ibrav=7,
>    celldm(1) =7.691188393, celldm(3)=3.756265356,
>    nat=7, ntyp=5,
>    ecutwfc=40, ecutrho=480,
>    occupations='smearing',smearing='gaussian',degauss=0.002,
>    nspin=2
>    starting_magnetization(2)=0.125
>    starting_magnetization(3)=-0.125
> !  nbnd=35
> !  lda_plus_u=.TRUE.
> !  Hubbard_U(2)=6.0
> /
> &electrons
>    electron_maxstep=300
>    mixing_beta = 0.3
>    conv_thr =  1.0d-10
> /
> &ions
>   bfgs_ndim= 3,
>   ion_dynamics='bfgs'
>   pot_extrapolation = 'second_order' ,
>   wfc_extrapolation = 'second_order' 
> /
> &CELL
>   cell_dynamics = 'bfgs' 
> /
> ATOMIC_SPECIES
> Na   22.99  Na.pw91-sp-van_ak.UPF 
> Fe1  55.845 Fe.pw91-sp-van_ak.UPF 
> Fe2  55.845 Fe.pw91-sp-van_ak.UPF 
> As   74.92  As.pw91-n-van.UPF
> O     16.00  O.pw91-van_ak.UPF 
> ATOMIC_POSITIONS {angstrom}      
> Na      0.0000000000     0.0000000000     4.7989032000
> Na      0.0000000000     0.0000000000    10.4890968000
> Fe1     0.0000000000    -2.0350000000     7.6440000000
> Fe2     2.0350000000     0.0000000000     7.6440000000
> As      0.0000000000     0.0000000000     1.8529056000
> As      0.0000000000     0.0000000000    13.4350944000
> O       0.0000000000     0.0000000000     7.6440000000
> K_POINTS {automatic}
> 4 4 4 1 1 1
> npool=2
> 
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--
Mr. Filippo SPIGA, M.Sc.
http://www.linkedin.com/in/filippospiga ~ skype: filippo.spiga

«Nobody will drive us out of Cantor's paradise.» ~ David Hilbert

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