[Pw_forum] phonon parallel calculations

[Carlo Nervi]

Thank you.
Meanwhile I'm continue to get strange errors. RAM seems ok. Apparently I'm
getting error only if I use the "-ni 8" option in ph.x. But it's random.
Here is the last error:

Program received signal SIGSEGV: Segmentation fault - invalid memory
reference.

Backtrace for this error:

Program received signal SIGSEGV: Segmentation fault - invalid memory
reference.

Backtrace for this error:
#0  0x2AF4EE34C78F
#1  0x2AF4EE34CD84
#2  0x2AF4EEFEBE6F
#3  0x2AF4EF032058
#4  0x51C509 in cgsolve_all_
#5  0x4E0486 in solve_linter_
#6  0x4BD7F6 in phqscf_
#7  0x45B666 in do_phonon_
#8  0x45758F in MAIN__ at phonon.f90:0



2015-02-20 10:06 GMT+01:00 Andrea Dal Corso <dalcorso at sissa.it>:

> On Fri, 2015-02-20 at 09:19 +0100, Carlo Nervi wrote:
> > Dear QE developers,
> > I would like to have your opinion on the procedure I followed in doing
> > phonon calculations.
> > I found that the use of nimages on my machine (8 numa zones) greatly
> > improves the speed of some calculations, but the first (initialization?)
> > part of the calculation (epsil=.true., i.e. the Electric Fields
> > Calculation) is much faster when performed without the use of "-ni 8"
> > switch in ph.x
> >
> > So, I tested the following procedure and apparently worked for a small
> test
> > crystal:
> >
> > 1) pw.x (vc-relax optimization) without using "-ni"
> > 2) scf on the optimized structure containing "wf_collect=.true." and
> using
> > "-ni 8"
>
> pw.x has no image parallelization, so step 2 should be done without
> images. The rest should be ok.
>
> HTH,
>
> Andrea
>
>
> > 3) ph.x containing "only_init = .true." and without using "-ni"
> >  This calculate the electric fields
> > 4) duplicate the directory _ph0 and copied to _ph1 ... _ph7 (in output
> > directory)
> > 5) ph.x containing "recover = .true." and using "-ni 8"
> >   This is the part where I get most of the speedup
> > 6) ph.x of the input used in 5), but now without using "-ni"
> >   This is to collect the partial data and produce the final .out
> >
> > I would greatly appreciate any comments in understanding if this
> procedure
> > is correct.
> > On a small crystal was working, but on a bigger crystal gave error.
> > Either the procedure is not completely correct or I have to start to look
> > for a problem in the RAM...
> >
> > Thank you,
> >
> >  Carlo
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://pwscf.org/mailman/listinfo/pw_forum
>
> --
> Andrea Dal Corso                    Tel. 0039-040-3787428
> SISSA, Via Bonomea 265              Fax. 0039-040-3787249
> I-34136 Trieste (Italy)             e-mail: dalcorso at sissa.it
>
>
> _______________________________________________
> Pw_forum mailing list
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> http://pwscf.org/mailman/listinfo/pw_forum
>



-- 

------------------------------------------------------------
Prof. Carlo Nervi carlo.nervi at unito.it  Tel:+39 0116707507/8
Fax: +39 0116707855      -      Dipartimento di Chimica, via
P. Giuria 7, 10125 Torino, Italy.    http://lem.ch.unito.it/
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