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Unstructured solid performance penalty when slice file output included

Open dvswenson opened this issue 5 years ago • 5 comments

I have just started testing some unstructured solids problems. One thing I noticed right away was that there was a big performance penalty when I added slices to the output. In the two attached models, the one without slices ran in 7 seconds and the one with three slices ran in 43 seconds.

Sincerely, Daniel Swenson Thunderhead Engineering user_guide_unstructured_solid.fds.txt user_guide_unstructured_solid_with_slices.fds.txt

dvswenson avatar Oct 12 '20 21:10 dvswenson

Thank you Dan. We'll have a look.

marcosvanella avatar Oct 12 '20 21:10 marcosvanella

An update on this, Glenn noted that the 6x difference in run times happens in windows. Also, seems the difference is still there when swapping the geometry by an OBST of similar size.

marcosvanella avatar Oct 13 '20 20:10 marcosvanella

Linux and osx difference closer to 1.5x. also difference proportional to number of slice files output and number of time steps output. I wonder if this is a file flushing issue.

On Tue, Oct 13, 2020, 4:04 PM marcosvanella [email protected] wrote:

An update on this, Glenn noted that the 6x difference in run times happens in windows. Also, seems the difference is still there when swapping the geometry by an OBST of similar size.

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gforney avatar Oct 13 '20 20:10 gforney

Good idea to check with an OBST. So this is probably not a practical issue, since on larger FDS 6 models slices are not a noticeable cost in the solution.

Maybe close this case?

dvswenson avatar Oct 14 '20 14:10 dvswenson

Hi Dan, let's leave it open for now while we try to understand why we see such a difference in timings for IO between Windows and Unix systems.

marcosvanella avatar Oct 14 '20 14:10 marcosvanella