[FLASH-USERS] Issue with Cray Compiler

[Klaus Weide]

On Wed, 11 Nov 2020, Alan Calder wrote:

> First I should note that things work well with the Gnu compilers. We do not
> see this problem when compiling with the gnu compilers.

That's good.

Does this also mean that you don't get any "WARNING after gc filling" 
messages with GNU compilers, in the situation where you did get them with 
the Cray compiler?


> The shortest possible summary is that the code seems to enter an unphysical
> state and crash, 

I don't have an idea what's going on here. Just want to point you to a 
couple of runtime parameters that you may find useful in this kind of 
situation:

   D dr_dtMinContinue  Minimum computed timestep to continue the simulation
   PARAMETER dr_dtMinContinue      REAL    0.0     [0.0 ...]

   D dr_dtMinBelowAction  Action to take when computed new timestep is below dr_dtMinContinue.
   D & Use 0 for none (abort immediately), 1 for "write checkpoint then abort"
   PARAMETER dr_dtMinBelowAction   INTEGER 1       [0,1]


> and with the split hydro solver I see a warning
> 
> WARNING after gc filling: min. unk(EINT_VAR)=9.9999999735241242E-11
>   PE=4     block=6
>                     type=1
> 

These indicate that you have very small values of internal energy in 
some cells. Not sure now whether that's kind of a normal thing for Sedov
close to the origin...  Maybe lower "smallE" to eliminate the warning?
Since this happens at the very beginning, maybe you can plot the initial
condition to figure out what's going on.

Not sure why this would not apply equally to "split" and "unsplit" Hydro.


> We compile with -c -g -G 2 -s real64 -s integer32 and the code generates a
> few warnings, none of which seem relevant.

I agree that the compilation warnings don't appear to be of immediate 
concern.

Klaus