[Users] [ET Trac] [Einstein Toolkit] #2008: NaNs when running static tov on >40 cores

[Gwyneth Allwright]

Hi Ian and Erik,

Thanks for your patience with this. Yes, I've moved on to larger
simulations, so please consider the scaling issues resolved.

Whether or not you decide to look into the problem with Carpet doesn't
really matter to me, but if you do, it would be interesting to hear what
was going wrong.

Gwyneth

On Tue, Mar 7, 2017 at 3:32 PM, Ian Hinder <ian.hinder at aei.mpg.de> wrote:

>
> On 23 Feb 2017, at 15:47, Erik Schnetter <schnetter at cct.lsu.edu> wrote:
>
> Regarding OpenMP:
>
> Cactus usually tries to optimize which treads run on which cores. If there
> are multiple independent processes running on a node, then Cactus must not
> do that, since this will slow down both applications a lot. In particular,
> must not set "CACTUS_SET_THREAD_BINDINGS=1" (not setting it or setting it
> to 0 is fine).
>
> As Ian mentioned, you can either build without OpenMP support, or choose
> to use a single thread at run time, both will work.
>
> At this time, it might be best to post your complete setup, i.e. all the
> options and scripts you are using to configure and build and submit and
> run, so that others can have a look and cross-check.
>
> Of course, all of this is independent of any nans you encounter. Those are
> still due to a bug. I don't think it makes much sense at this point to
> debug this -- instead, you will want to run a larger simulations.
>
>
> Hi Erik,
>
> Are you suggesting that it is not worth us debugging the problem with
> Carpet which is giving wrong results if too many processes are used?  This
> could be triggered in other situations; we don't know what the origin is.
>
> If you mean that Gwyneth would be better off focusing on larger
> simulations than trying to get this one to work on so many processes, then
> I agree.
>
> --
> Ian Hinder
> http://members.aei.mpg.de/ianhin
>
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