[FLASH-USERS] Timing problem in LaserSlab example

Reem Alraddadi raba500 at york.ac.uk
Tue Aug 20 11:32:50 EDT 2013


I have forgotten to mention  that I am using FLASH4.0.1

Thanks,
Reem

Message: 1
> Date: Tue, 20 Aug 2013 16:29:08 +0100
> From: Reem Alraddadi <raba500 at york.ac.uk>
> Subject: [FLASH-USERS] Timing problem in LaserSlab example
> To: flash-users at flash.uchicago.edu
> Message-ID:
>         <CANKsntF54R6Yc6DEhLAB_H4TahadE=
> 1cG9T_LiPNJY-uE2HgJw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Klaus,
>
>
> When I increased the number of process to 32 and decreased nend to 3000, it
> works without any problem and the run successfully completed, reaching to
> 109ps. However, when I only changed Cu temperature from 25 eV to 50 eV, the
> problem occurs again. Any ideas?
>
> Thanks,
> Reem
>
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Fri, 16 Aug 2013 15:47:51 -0500 (CDT)
> > From: Klaus Weide <klaus at flash.uchicago.edu>
> > Subject: Re: [FLASH-USERS] Timing problem in LaserSlab example
> > To: Reem Alraddadi <raba500 at york.ac.uk>
> > Cc: flash-users at flash.uchicago.edu
> > Message-ID: <Pine.LNX.4.64.1308161521420.24703 at flash.uchicago.edu>
> > Content-Type: TEXT/PLAIN; charset=US-ASCII
> >
> > On Fri, 16 Aug 2013, Reem Alraddadi wrote:
> >
> > > Hi all,
> > >
> > > I am running a Modified LaserSlab example for three materials with the
> > > following setup line:
> > >
> > > Slab3 -2d +pm4dev -nxb=16 -nyb=16 +mtmmmt +mgd species=cham,targ,foil
> > > mgd_meshgroups=6 -parfile=example.par +3t -maxblocks=1000
> > >
> > > the run goes OK at the first time with lrefine_max=6 but when I goes
> > > with lrefine_max=9
> > > I got the following warning message :
> > >
> > > Warning: The initial timestep is too large.
> > >
> > > initial timestep = 1.000000000000000E-014
> > >
> > > CFL timestep = 5.139420973957487E-014
> > >
> > > Resetting dtinit to TIMESTEP_SLOW_START_FACTOR*dtcfl.
> >
> > [...]
> >
> > > So I reduced the initial time step and made dtinit=dtmin=0.1e-14  and I
> > > increased nend to 8000 as I am really interested in time when it
> reaches
> > to
> > > 50ps until 200ps. However, by doing that , the warning message does not
> > > exist any more but ...
> >
> > Reem,
> >
> > You did not necessarily have to modify dtinit, since (as the Warning
> > message tries to say) the initial dt was reset to 0.5139420973957487e-14
> > automatically. (I believe TIMESTEP_SLOW_START_FACTOR is hardwired to
> 0.1.)
> > It is good that you decreased dtmin. It may also be good that you
> > decreased dtinit to below that automatic value.
> >
> > However, those things are probably unrelated to the ultimate failure of
> > your runs.
> >
> > >   I found the run didn't complete and just reach when
> > > t=5e-11 and n step was only 1809 . Also, I found an output file regard
> to
> > > Hypre library which I didn't understand what does mean. I have attached
> > > with this e-mail my flash.par file, out.log, lasslab.log and the output
> > > messages regard to Hpyre file. I need my run reach to time from 50ps
> > until
> > > 200 ps. Could you help me with this, please?
> >
> > It seems you got to ~ 53 ps. Then the run(s) failed.
> >
> > You did not provide the contents of the err.err file, even though
> > your output.log says (twice):
> >
> >    PS:
> >
> >    Read file <err.err> for stderr output of this job.
> >
> > Maybe there are some messages in that file explaining while the run(s)
> > failed.
> >
> > You may have exceeded the allowed CPU time in your batch system, or may
> > have run out of memory, or some similar reason.
> >
> > > PS:  the flash,par is as same as example.par. Also,I wonder if the
> > problem
> > > because I run the same problem twice. I found that by mistake I run the
> > > same file twice. Is this the reason that the run didn't complete ?
> >
> > I don't know. But it seems you had two instances of the same simulation
> > running in the same directory, overwriting each other's output files
> > and both writing interspersed lines to the log file. It is unnecessarily
> > difficult to analyze from this output what has actually happened.
> >
> > I would suggest you
> >  * restart, making sure this time that only one instance of the code is
> >    running.
> >  * You may restart from a checkpoint instead of starting from step 1,
> >    to save time (you seem to have dumped checkpoints frequently).
> >  * If the run fails again, make sure you look at all available output
> >    including any err.err file.
> >
> > > and what
> > > does hypre message mean?
> >
> > Apparently the run (or at least one of them? - it is unclear whether
> > the hypre stack traces were generated by one or by both runs) died while
> > at least some processors where in a hypre function.  It is unclear
> > to me whether those processors actually caused signals that resulted in
> > aborting the runs.
> >
> > Btw. it isn't clear what version of FLASH you were using. I hope you are
> > using 4.0.1, because it includes a hypre-related fix to 4.0.
> >
> > Klaus
> >
> >
> > ------------------------------
> >
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> >
> >
> > End of flash-users Digest, Vol 70, Issue 8
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