[Nek5000-users] Simulation hanging at 'mapping elements to processors'

[nek5000-users at lists.mcs.anl.gov]

Marco,

can you please post your logfile. What version of Nek5000 do you use?

Cheers,
Stefan

-----Original message-----
> From:nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
> Sent: Friday 22nd September 2017 2:40
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Simulation hanging at 'mapping elements to processors'
> 
> Hi Paul,
> <br class="" />
> thanks for the help. I will give it a try tomorrow. I am indeed using the XXT coarse grid solver.
> <br class="" />
> Marco
> <br class="" />
> On Sep 21, 2017, at 6:49 PM, 
> nek5000-users at lists.mcs.anl.gov <mailto:nek5000-users at lists.mcs.anl.gov> <Nek5000-users at lists.mcs.anl.gov <mailto:Nek5000-users at lists.mcs.anl.gov>> wrote:
> <br class="Apple-interchange-newline" />
> <br class="Apple-interchange-newline" />
> Hi Marco,
> <br class="" />
> I'm not 100 % about the hanging point, but I suggest - especially for larger problems like this - running on a power of 2 processors (i.e., 1024 in your case).
> <br class="" />
> This is particularly critical for performance when the XXT (default) coarse grid solver is used.  Less so, perhaps, for the AMG coarse solver...I'm assuming you're using the XXT one - but not certain.
> <br class="" />
> Best,
> <br class="" />
> Paul
> <br class="" />
> -----------
> From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov <mailto:nek5000-users-bounces at lists.mcs.anl.gov>>
>  on behalf of nek5000-users at lists.mcs.anl.gov <mailto:nek5000-users at lists.mcs.anl.gov> <nek5000-users at lists.mcs.anl.gov <mailto:nek5000-users at lists.mcs.anl.gov>><br class="" />
> Sent: Thursday, September 21, 2017 3:37:55 PM<br class="" />
> To: Nek5000-users at lists.mcs.anl.gov <mailto:Nek5000-users at lists.mcs.anl.gov><br class="" />
> Subject: [Nek5000-users] Simulation hanging at 'mapping elements to processors'
> Hello,<br class="" />
> <br class="" />
> I am trying to run a simulation that has ~500,000 elements on 1280 processors with lx1=4 for debugging purposes. My simulation hangs after outputting 'mapping elements to processors’. I generated the mesh with Cubit and then used the exo2nek script to get the
>  re2 file. Genmap runs fine on the re2 file.<br class="" />
> <br class="" />
> I was wondering if this problem has been encountered in the past, and what I could do to fix it.<br class="" />
> <br class="" />
> Thanks,<br class="" />
> Marco<br class="" />
> <br class="" />
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